Documents
Resources
Learning Center
Upload
Plans & pricing Sign in
Sign Out

java tutorial (PDF)

VIEWS: 114 PAGES: 11

									Java Programming Guide - Quick Reference                                  Java Programming Guide - Quick Reference

 Syntax for a standalone application in Java:                                 Java Comments:

 class <classname>                                                            Delimiters                                   Use
 {                                                                            //                         Used for commenting a single line
      public static void main(String args[])
       {                                                                      /* ————— */                Used for commenting a block of code
           statements;
           ————————;                                                          /** —————*/                Used for commenting a block of code.
           ————————;                                                                                       Used by the Javadoc tool for
       }                                                                                                  generating Java documentation.
 }
                                                                              Primitive datatypes in Java:
 Steps to run the above application:

 1. Type the program in the DOS editor or notepad. Save the                   DataType          Size         Default              Min Value
       file with a .java extension.                                                                                               Max Value
 2. The file name should be the same as the class, which has the               byte
    main method.                                                              (Signed                                            -128
 3. To compile the program, using javac compiler, type the                     integer)         8 bits        0                  +127
    following on the command line:
      Syntax: javac <filename.java>                                           short
      Example: javac abc.java                                                 (Signed                                            -32,768
 4. After compilation, run the program using the Java                          integer)         16 bits      0                   +32,767
     interpreter.
      Syntax: java <filaname> (without the .java                              int
                 extension)                                                   (Signed                                            -2,147,483,648
    Example: java abc                                                          integer)         32 bits      0                   +2,147,483,647
 5. The program output will be displayed on the command line.
                                                                              long                                       -9, 223, 372,036,854,
                                                                              (Signed                                     775,808,
                                                                              Integer)                                   +9,223,372,036,
                                                                                                64 bits      0           854, 775, 807


© 1999, Pinnacle Software Solutions Inc.                              1   © 1999, Pinnacle Software Solutions Inc.                                3




Java Programming Guide - Quick Reference                                  Java Programming Guide - Quick Reference


   Java reserved words:

   abstract     default    if             package        this                 float              32 bits     0.0       1.4E-45
   boolean     do          implements     private        throw               (IEEE 754                                 3.4028235E38
   Break       double      import         protected       throws              floating-point)
   Byte         else        instanceof   public           transient
   case         extends    int            return         null                 double             64 bits     0.0       4.9E-324
   try         Const       for           new             switch              (IEEE 754                                 1.7976931348623157E308
   continue     while      goto           synchronized   super                floating-point)
   Catch       final       interface     short           void
   char        finally    long           static          volatile
   class       float       native
                                                                            char                  16 bits \u0000 \u0000
                                                                            (Unicode
                                                                            character)                                  \uFFFF
    Java naming conventions:
                                                                            boolean               1 bit      false
    Variable Names: Can start with a letter, ‘$’ (dollar symbol),
    or ‘_’ (underscore); cannot start with a number; cannot be a
    reserved word.
                                                                              Variable Declaration:
    Method Names: Verbs or verb phrases with first letter in                  <datatype> <variable name>
    lowercase, and the first letter of subsequent words                       Example: int num1;
    capitalized; cannot be reserved words.
    Example: setColor()                                                       Variable Initialization:
                                                                              <datatype>       <variable name> = value
    Class And Interface Names: Descriptive names                              Example: double num2 = 3.1419;
    that begin with a capital letter, by convention; cannot be a
    reserved word.                                                            Escape sequences:
                                                                               Literal                            Represents
    Constant Names: They are in capitals.                                     \n                                  New line
    Example: Font.BOLD, Font.ITALIC                                           \t                                  Horizontal tab
                                                                              \b                                  Backspace
                                                                              \r                                  Carriage return

© 1999, Pinnacle Software Solutions Inc.                              2   © 1999, Pinnacle Software Solutions Inc.                                4
Java Programming Guide - Quick Reference                               Java Programming Guide - Quick Reference

                                                                         5. Switch statement
    \f                          Form feed                                   Syntax:
    \\                          Backslash                                     switch(variable)
    \”                          Double quote                                {
    \ddd                        Octal character                                case(value1):
    \xdd                        Hexadecimal character                          statements;
    \udddd                      Unicode character                              break;
                                                                               case(value2):
                                                                               statements;
    Arrays: An array which can be of any datatype, is created in               break;
    two steps – array declaration and memory allocation.                       default:
                                                                               statements;
    Array declaration                                                          break;
    <datatype> [] <arr ```````````ayname>;                                     }
    Examples int[] myarray1;
                  double[] myarray2;                                    Class Declaration: A class must be declared using the
    Memory Allocation                                                   keyword class followed by the class name.
    The new keyword allocates memory for an array.                      Syntax
    Syntax                                                              class <classname>
    <arrayname> = new <array type> [<number of                          {
    elements>];                                                            ———— Body of the class
    Examples
    myarray1 = new int[10];                                             A typical class declaration is as follows:
    Myarray2 = new double[15];                                          <modifier> class <classname> extends
                                                                        <superclass name> implements <interface name>
    Multi-dimensional arrays:                                           {
                                                                            —————Member variable declarations;
    Syntax:                                                                 —————Method declarations and definitions
    <datatype> <arrayname> [] [] = new <datatype>                       }
    [number of rows][number of columns];
    Example:
    int mdarray[][] = new int[4][5];



© 1999, Pinnacle Software Solutions Inc.                           5   © 1999, Pinnacle Software Solutions Inc.                        7




Java Programming Guide - Quick Reference                               Java Programming Guide - Quick Reference

    Flow Control:                                                       Member variable declarations:

     1. If……..else statements                                           <access specifier> <static/final/transient/
       Syntax:                                                          volatile> <datatype> <variable name>
         if(condition)                                                  Example public final int num1;
      {
         statements;                                                    Method declarations:
      }
      else                                                              <access specifier> <static/final> <return type>
      {                                                                 <method name> <arguments list>
        statements;                                                     {
      }                                                                   Method body;
                                                                        }
    2. For loop                                                         Example public static void main(String args[])
       Syntax:                                                                   {
        for(initialization; condition; increment)                                }
       {
          statements;                                                   Interface declaration: Create an interface. Save the file
        }                                                               with a.java extension, and with the same name as the
                                                                        interface. Interface methods do not have any implementation
     3. While loop                                                      and are abstract by default.
        Syntax:
        while(condition)                                                Syntax
        {                                                                 interface <interface name>
          statements;                                                    {
        }                                                                  void abc();
                                                                           void xyz();
    4. Do….While loop                                                    }
       Syntax:
       do                                                               Using an interface: A class implements an interface with the
       {                                                                implements keyword.
           statements;
       }
       while(condition);
© 1999, Pinnacle Software Solutions Inc.                           6   © 1999, Pinnacle Software Solutions Inc.                        8
Java Programming Guide - Quick Reference                                  Java Programming Guide - Quick Reference

 Syntax
 class <classname> extends <superclass name>
 implements <interface name>                                               final               Class       Cannot be subclassed.
 {
   class body;                                                                                 Method      Cannot be overridden.
   —————————;
 }                                                                                             Variable    Value cannot be changed
                                                                                                           (Constant)
    Creating A Package:
                                                                           native              Method      Implemented in a language
    1.   Identify the hierarchy in which the .class files have to                                          other than Java like C,C++,
         be organized.                                                                                     assembly etc. Methods do not
    2.   Create a directory corresponding to every package, with                                           have bodies.
         names similar to the packages.
    3.   Include the package statement as the first statement in           static              Method      Class method. It cannot refer to
         the program.                                                                                      nonstatic variables and methods
    4.   Declare the various classes.                                                                      of the class. Static methods are
    5.   Save the file with a .java extension.                                                             implicitly final and invoked
    6.   Compile the program which will create a .class file in                                            through the class name.
         the same directory.
    7.      Execute the .class file.                                                           Variable    Class variable. It has only one
                                                                                                           copy regardless of how many
   Packages and Access Protection:                                                                         instances are created. Accessed
                                                                                                           only through the class name.
  Accessed         Public     Protected     Package        Private
  From the                                                                 synchronized        Method      A class which has a synchronized
  same class ?       Yes         Yes             Yes             Yes                                       method automatically acts as a
                                                                                                           lock. Only one synchronized
  From a non                                                                                               method can run for each class.
  subclass in
  the same
  package ?          Yes         Yes             Yes             No



© 1999, Pinnacle Software Solutions Inc.                              9   © 1999, Pinnacle Software Solutions Inc.                           11




Java Programming Guide - Quick Reference                                  Java Programming Guide - Quick Reference

                                                                            List of exceptions in Java(part of java.lang package):
  From a non
  subclass                                                                  Essential exception classes include -
  outside the
  package?           Yes         No              No              No       Exception                           Description

  From a                                                                  ArithmeticException                 Caused by exceptional
  subclass                                                                                                       conditions like divide by
  in the same                                                                                                 zero
  package?           Yes         Yes             Yes             No
                                                                          ArrayIndexOfBounds                Thrown when an array is
  From a                                                                  Exception                          accessed beyond its bounds
  subclass
  outside the                                                             ArrayStoreException                Thrown when an incompatible
  package ?          Yes         Yes              No             No                                           type is stored in an array

                                                                          ClassCastException                 Thrown when there is an invalid
                                                                                                              cast
 Attribute modifiers in Java:
                                                                          IllegalArgument                    Thrown when an inappropriate
 Modifier        Acts on       Description                                Exception                          argument is passed to a method
 abstract         Class        Contains abstract
                                 methods.Cannot                           IllegalMonitorState               Illegal monitor operations such as
                                be instantiated.                          Exception                          waiting on an unlocked thread

                  Interface      All interfaces are implicitly            IllegalThreadState                Thrown when a requested
                                 abstract. The modifier is                Exception                          operation is incompatible with
                                 optional.                                                                    the current thread state.

                  Method        Method without a body.                    IndexOutOfBounds                  Thrown to indicate that an index
                                Signature is followed by a                Exception                          is out of range.
                                semicolon. The class must also
                                be abstract.                              NegativeArraySize                 Thrown when an array is created
                                                                          Exception                          with negative size.
© 1999, Pinnacle Software Solutions Inc.                          10      © 1999, Pinnacle Software Solutions Inc.                           12
Java Programming Guide - Quick Reference                                   Java Programming Guide - Quick Reference

NullPointerException          Invalid use of a null reference.               setPriority()              Changes the priority of the thread

NumberFormatException          Invalid conversion of a string to a            currentThread()           Returns a reference to the
                               number.                                                                  currently executing thread

SecurityException              Thrown when security is violated.              activeCount()              Returns the number of active
                                                                                                         threads in a thread group
ClassNotFound                  Thrown when a class is not found.
Exception
                                                                              Exception Handling Syntax:
CloneNotSupported             Attempt to clone an object that
Exception                      does not implement the Cloneable               try
                               interface.                                     {
                                                                                     //code to be tried for errors
 IllegalAccess                Thrown when a method does not                    }
 Exception                     have access to a class.                             catch(ExceptionType1 obj1)
                                                                               {
 Instantiation                Thrown when an attempt is made                         //Exception handler for ExceptionType1
Exception                      to instantiate an abstract class or             }
                               an interface.                                        catch(ExceptionType2 obj2)
                                                                               {
 InterruptedException          Thrown when a second thread                           //Exception handler for ExceptionType2
                                 interrupts a waiting, sleeping, or            }
                                 paused thread.                                    finally{
                                                                                   //code to be executed before try block ends.
                                                                                      This executes whether or not an //
                                                                                      exception occurs in the try block.
                                                                                   }

 The java.lang.Thread class                                                  I/O classes in Java (part of the java.io package):

 The Thread class creates individual threads. To create a thread             I/O class name                 Description
 either (i) extend the Thread class or (ii) implement the Runnable
 interface. In both cases, the run() method defines operations               BufferedInputStream            Provides the ability to buffer the

© 1999, Pinnacle Software Solutions Inc.                              13   © 1999, Pinnacle Software Solutions Inc.                          15




Java Programming Guide - Quick Reference                                   Java Programming Guide - Quick Reference

 performed by the thread.
                                                                                                        input. Supports mark() and
 Methods of the Thread class:                                                                           reset() methods.
                                                                             BufferedOutputStream     Provides the ability to write bytes
   Methods                    Description                                                              to the underlying output stream
                                                                                                      without making a call to the
   run()                      Must be overridden by                                                   underlying system.
                              Runnable object; contains code
                              that the thread should perform                BufferedReader                  Reads text from a character
   start()                    Causes the run method to                                                      input stream
                              execute and start the thread                  BufferedWriter                  Writes text to character
                                                                                                            output stream
   sleep()                    Causes the currently executing                DataInputStream                 Allows an application to read
                              thread to wait for a specified time                                           primitive datatypes from an
                              before allowing other threads to                                              underlying input stream
                              execute                                       DataOutputStream                Allows an application to write
                                                                                                            primitive datatypes to an output
   interrupt()                Interrupts the current thread                                                 stream
                                                                            File                            Represents disk files and
  Yield()                     Yields the CPU to other runnable                                              directories
                              threads                                       FileInputStream                 Reads bytes from a file in a file
                                                                                                            system
  getName()                   Returns the current thread’s name             FileOutputStream                Writes bytes to a file
                                                                            ObjectInputStream               Reads bytes i.e. deserializes
  getPriority()               Returns the thread’s priority as an                                           objects using the
                              integer                                                                       readObject() method
                                                                            ObjectOutputStream              Writes bytes i.e. serializes
  isAlive()                   Tests if the thread is alive; returns                                         objects using the
                              a Boolean value                                                               writeObject()method
                                                                            PrintStream                     Provides the ability to print
  join()                      Waits for specified number of                                                 different data values in an
                              milliseconds for a thread to die                                              efficient manner
                                                                            RandomAccessFile                Supports reading and writing to
  setName()                   Changes the name of the thread                                                a random access file
© 1999, Pinnacle Software Solutions Inc.                              14   © 1999, Pinnacle Software Solutions Inc.                          16
Java Programming Guide - Quick Reference                                Java Programming Guide - Quick Reference

 StringReader                      Character stream that reads            getName()      Returns the name of the file and directory
                                   from a string                                         denoted by the path name
                                                                          isDirectory() Tests whether the file represented by the
 StringWriter                      Character stream that writes to                       pathname is a directory
                                   a StringBuffer that is later           lastModified() Returns the time when the file was last
                                   converted to a String                                 modified
                                                                        l length()       Returns the length of the file represented by
                                                                                         the pathname
 The java.io.InputStream class: The InputStream class is                  listFiles()    Returns an array of files in the directory
 at the top of the input stream hierarchy. This is an abstract class                     represented by the pathname
 which cannot be instantiated. Hence, subclasses like the                  setReadOnly() Marks the file or directory so that only
 DataInputStream class are used for input purposes.                                        read operations can be performed
                                                                            renameTo()    Renames the file represented by the
  Methods of the InputStream class:                                                       pathname
                                                                           delete()       Deletes the file or directory represented by
  Method              Description                                                         the pathname
 available()          Returns the number of bytes that can be              canRead()      Checks whether the application can read
                      read                                                                from the specified file
                                                                            canWrite()    Checks whether an application can write to
 close()              Closes the input stream and releases                                a specified file
                      associated system resources

 mark()               Marks the current position in the input             Creating applets:
                      stream
 mark                                                                       1.    Write the source code and save it with a .java
 Supported()          Returns true if mark() and reset() methods                  extension
                      are supported by the input stream                     2.    Compile the program
                                                                            3.    Create an HTML file and embed the .class file with the
 read()               Abstract method which reads the next byte                   <applet> tag into it.
                      of data from the input stream                         4.    To execute the applet, open the HTML file in the browser
                                                                                  or use the appletviewer utility, whch is part of the Java
 read(byte b[]) Reads bytes from the input stream and                             Development Kit.
                stores them in the buffer array


© 1999, Pinnacle Software Solutions Inc.                           17   © 1999, Pinnacle Software Solutions Inc.                          19




Java Programming Guide - Quick Reference                                Java Programming Guide - Quick Reference

 skip()               Skips a specified number of bytes from the         The <applet> tag: Code, width, and height are
                      input stream                                       mandatory attributes of the <applet> tag. Optional attributes
                                                                         include codebase, alt,name, align, vspace, and
                                                                         hspace. The code attribute takes the name of the class file as
 The java.io.OutputStream class: The OutputStream class                  its value.
 which is at the top of the output stream hierarchy, is also an          Syntax:
 abstract class, which cannot be instantiated. Hence, subclasses         <applet code = “abc.class” height=300
 like DataOutputStream and PrintStream are used for                      width=300>
 output purposes.                                                        <param name=parameterName1           value= value1 >
                                                                         <param name=parameterName2           value= value2 >
 Methods of the OutputStream class:                                      </applet>

 Method                 Description                                      Using the Appletviewer: Appletviewer.exe is an
                                                                         application found in the BIN folder as part of the JDK. Once an
 close()                Closes the output stream, and releases           HTML file containing the class file is created (eg. abc.html),
                        associated system resources                      type in the command line:
                                                                         Appletviewer       abc.html
 write(int b)           Writes a byte to the output stream
                                                                          java.applet.Applet class:
 write(byte b[])        Writes bytes from the byte array to the
                        output stream                                     Methods of the java.applet.Applet class:

 flush()                Flushes the ouput stream, and writes             Method                        Description
                        buffered output bytes
                                                                         init()                        Invoked by the browser or the
                                                                                                       applet viewer to inform that the
  java.io.File class: The File class abstracts information                                             applet has been loaded
 about files and directories.                                            start()                       Invoked by the browser or the
                                                                                                       applet viewer to inform that
 Methods of the File class:                                                                            applet execution has started
                                                                         stop()                        Invoked by the browser or the
  Method             Description                                                                       applet viewer to inform that
                                                                                                       applet execution has stopped
  exists()           Checks whether a specified file exists
© 1999, Pinnacle Software Solutions Inc.                           18   © 1999, Pinnacle Software Solutions Inc.                          20
Java Programming Guide - Quick Reference                               Java Programming Guide - Quick Reference


  destroy()                    Invoked by the browser or the             setBackground()             Sets the background color of the
                               appletviewer to inform that the                                       component
                               applet has been reclaimed by the          setForeground()             Sets the foreground color of the
                               Garbage Collector                                                     component
  getAppletContext()           Determines the applet context or          SetSize()                   Resizes the component
                               the environment in which it runs          setLocation()               Moves the component to a new
  getImage()                   Returns an Image object that can                                      location
                               be drawn on the applet window             setBounds()                 Moves the component to specified
                                                                                                     location and resizes it to the
  getDocumentBase()            Returns the URL of the HTML page                                      specified size
                               that loads the applet                     addFocusListener()          Registers a FocusListener
                                                                                                     object to receive focus events
  getCodeBase()                Returns the URL of the applet’s                                       from the component
                               class file                                addMouseListener()          Registers a MouseListener
  getParameter()               Returns the value of a named                                          object to receive mouse events
                               applet parameter as a string                                          from the component
  showStatus()                 Displays the argument string on           addKeyListener()            Registers a KeyListener object
                               the applet’s status                                                   to receive key events from the
                                                                                                     component
                                                                         getGraphics()               Returns the graphics context of
 java.awt.Graphics class: The Graphics class is an                                                   this component
 abstract class that contains all the essential drawing methods          update(Graphics g)          Updates the component. Calls the
 like drawLine(), drawOval(), drawRect() and so on. A                                                paint() method to redraw the
 Graphics reference is passed as an argument to the paint()                                          component.
 method that belongs to the java.awt.Component class.

  Methods of the Graphics class:                                         AWT Components: Many AWT classes like Button,
                                                                        Checkbox, Label, TextField etc. are subclasses of the
  Method                Description                                     java.awt.Component class. Containers like Frame and
  drawLine()            Draws a line between (x1,y1) and                Panel are also subclasses of components, but can additionally
                        (x2,y2) passed as parameters                    hold other components.
  drawRect()/fillRect() Draws a rectangle of specified
                        width and height at a specified

© 1999, Pinnacle Software Solutions Inc.                          21   © 1999, Pinnacle Software Solutions Inc.                          23




Java Programming Guide - Quick Reference                               Java Programming Guide - Quick Reference

                                                                         Label:
                                location
                                                                          Constructors
  drawOval()/fillOval() Draws a circle or an ellipse that                  ·   Label() - Creates an empty label
                        fills within a rectangle of specified              ·   Label(String s) - Creates a label with left
                        coordinates                                            justified text string
  drawString()          Draws the text given as a                          ·   Label (String s, int alignment) - Creates
                        specified string                                       a label with the specified text and specified aligment.
  drawImage()           Draws the specified image onto                         Possible values for alignment could be Label.RIGHT,
                        the screen                                             Label.LEFT, or Label.CENTER
   drawPolygon()
  /fillPolygon()          Draws a closed polygon defined                   Methods of the Label class:
                            by arrays of x and y coordinates
                                                                          Method                     Description
  setColor()                   Sets the specified color of the
                               graphics context                           getAlignment()             Returns an integer representing
                                                                                                     the current alignment of the Label.
  setFont()                    Sets the specified font of the                                        0 for left, 1 for center, and 2 for
                               graphics context                                                      right alignment.
                                                                          setAlignment()             Sets the alignment of the Label to
                                                                                                     the specified one
  java.awt.Component class: The Component class is an                     getText()                  Returns the label’s text as a
 abstract class that is a superclass of all AWT components. A                                        string
 component has a graphical representation that a user can                 setText()                  Sets the label’s text with the
 interact with. For instance, Button, Checkbox,                                                      specified string
 TextField, and TextArea.

  Methods of the Component class:                                        Button:

  Method                       Description                               Constructors

  paint(Graphics g)            Paints the component. The                 Button() - Creates a button without a label
                               Graphics context g is used for            Button(String s) - Creates a button with the specified
                               painting.                                 label
© 1999, Pinnacle Software Solutions Inc.                          22   © 1999, Pinnacle Software Solutions Inc.                          24
Java Programming Guide - Quick Reference                                     Java Programming Guide - Quick Reference

      Methods of the Button class:
                                                                              Choice() - Creates a new choice menu, and presents a pop-
  Method                            Description                               up menu of choices.
  addActionListener()               Registers an ActionListener
                                    object to receive action events           Methods of the Choice class:
                                    from the button
                                                                              Method                       Description
   getActionCommand()               Returns the command name of
                                    the action event fired by the             add()                        Adds an item to a choice menu
                                    button. Returns the button label
                                    if the command name is null.              addItem()                    Adds an item to a choice menu

   GetLabel()                       Returns the button’s label                addItemListener()            Registers an ItemListener object
                                                                                                           to receive item events from the
   SetLabel()                       Sets the button’s label to the                                         Choice object
                                    specified string
                                                                              getItem()                    Returns the item at the specified
                                                                                                           index as a string
  Checkbox:
                                                                              getItemCount()               Returns the number of items in the
  Constructors                                                                                             choice menu

  ·         Checkbox() - Creates a checkbox without any label                 getSelectedIndex()           Returns the index number of the
  ·         Checkbox(String s) - Creates a checkbox with a                                                 currently selected item
            specified label
  ·         Checkbox(String s, boolean state) - Creates                       getSelectedItem()            Returns the currently selected item
            a checkbox with a specified label, and sets the specified                                      as a string
            state
  ·         Checkbox(String s, boolean state,                                 insert()                     Inserts a specified item at a specified
            CheckboxGroup cbg) - Creates a checkbox with a                                                 index position
            specified label and specified state, belonging to a
            specified checkbox group                                          remove()                     Removes an item from the choice
                                                                                                           menu at the specified index


© 1999, Pinnacle Software Solutions Inc.                                25   © 1999, Pinnacle Software Solutions Inc.                            27




Java Programming Guide - Quick Reference                                     Java Programming Guide - Quick Reference

   Methods of the Checkbox class:                                             TextField:

   Method                          Description                                Constructors

   addItemListener()               Registers an ItemListener                  · TextField() - Creates a new text field
                                   object to receive item events from         · TextField(int cols) - Creates a text field with the
                                   the checkbox                                 specified number of columns
                                                                              · TextField(String s) – Creates a text field initialized with
   getCheckboxGroup()              Returns the checkbox’s group                 a specified string
                                                                              · TextField(String s, int cols) - Creates a text field
      getLabel()                   Returns the checkbox’s label                  initialized with a specified string that is wide enough to hold a
                                                                                 specified number of columns
      getState()                   Determines if the checkbox
                                   is checked or unchecked                     Methods of the TextField class:

      setLabel()                   Sets the label of the check box             Method                         Description
                                   with the specified string
                                                                               isEditable()                  Returns a boolean value indicating
      setState()                   Sets the specified checkbox state                                         whether or not a text field is
                                                                                                             editable

                                                                               setEditable()                 Passing True enables text to be
           Creating Radio Buttons (Mutually exclusive checkboxes):                                           edited, while False disables
                                                                                                             editing. The default is True.
       ·      First create a CheckboxGroup instance –
              CheckboxGroup cbg = new CheckboxGroup();                        addActionListener()             Registers an ActionListener
       ·      While creating the checkboxes, pass the checkbox group                                          object to receive action events
              object as an argument to the constructor - Checkbox                                             from a text field
              (String s, boolean state, CheckboxGroup
              cbg)                                                            getEchoChar()                   Returns the character used for
                                                                                                              echoing
  Choice:
                                                                              getColumns()                    Returns the number of columns
  Constructors                                                                                                in a text field
© 1999, Pinnacle Software Solutions Inc.                                26   © 1999, Pinnacle Software Solutions Inc.                            28
Java Programming Guide - Quick Reference                              Java Programming Guide - Quick Reference

 setEchoChar()                  Sets the echo character for a text      Methods of the List class:
                                field
 getText()                      Returns the text contained in the       Method                       Description
                                text field
 setText()                      Sets the text for a text field          add()                        Adds an item to the end of the
                                                                                                     scrolling list

 TextArea:                                                              addItemListener()            Registers an ItemListener
                                                                                                     object to receive Item events from
 Constructors                                                                                        a scrolling list

 · TextArea() - Creates a new text area                                 deselect()                   Deselects the item at the specified
 · TextArea(int rows, int cols) - Creates a new                                                      index position
   empty text area with specified rows and columns
 · TextArea(String s) – Creates a new text area with the                getItem()                    Returns the item at the specified
   specified string                                                                                  index position
 · TextArea(String s, int rows, int cols) - Creates
   a new text area with the specified string and specified rows         getItemCount()               Returns the number of items in the
   and columns.                                                                                      list
 · TextArea(String s, int rows, int cols, int
    scrollbars) - Creates a text area with the specified text,          getSelectedIndex()           Returns the index position of the
    and rows, columns, and scrollbar visibility as specified.                                        selected item

  Methods of the TextArea class:                                        getSelectedItem()            Returns the selected item on the
                                                                                                     scrolling list
  Method                        Description
                                                                        isMultipleMode()             Determines if the scrolling
  getText()                     Returns the text contained in the                                    list allows multiple selection
                                text area as a string
                                                                        remove()                     Removes a list item from a
  setText()                     Sets the specified text in the text                                  specified position
                                area
                                                                        setMultipleMode()            Sets a flag to enable or disable
  getRows()                     Returns the number of rows in the                                    multiple selection

© 1999, Pinnacle Software Solutions Inc.                              © 1999, Pinnacle Software Solutions Inc.




Java Programming Guide - Quick Reference                              Java Programming Guide - Quick Reference
                                                                       Scrollbar:

                                                                       Constructors
                              text area
  getColumns()               Returns the number of columns in          · Scrollbar() - Creates a new vertical scroll bar
                              the text area                            · Scrollbar(int orientation) - Creates a new scroll
                                                                          bar with a particular orientation, which is specified as
  selectAll()                Selects all the text in the text area        Scrollbar.HORIZONTAL or Scrollbar.VERTICAL
                                                                       · Scrollbar(int orientation, int value,
  setEditable()              A True value passed as an                   int visible, int minimum, int maximum)- Creates
                             argument enables editing of the             a new scroll bar with the specified orientation, initial value,
                             text area, while False disables            thumb size, minimum and maximum values
                             editing. It is True by default.
                                                                        Methods of the Scrollbar class:

 List:                                                                  Method                               Description

 Constructors                                                           addAdjustmentListener()              Registers an
                                                                                                             adjustmentListener object
 · List() - Creates a new scrolling list                                                                     to receive adjustment
 · List(int rows) - Creates a new scrolling list with a                                                      events from a scroll bar
   specified number of visible lines                                    getBlockIncrement()                  Returns the block
 · List(int rows, boolean multiple) - Creates a                                                              increment of a scrollbar
   scrolling list to display a specified number of rows. A True                                              as an integer.
   value for Multiple allows multiple selection, while a False          getMaximum()                         Returns the maximum
   value allows only one item to be selected.                                                                value of a scrollbar as an
                                                                                                             integer
                                                                        getMinimum()                         Returns the minimum
                                                                                                             value of a scrollbar as an
                                                                                                             integer
                                                                        getOrientation()                     Returns the orientation of
                                                                                                             a scrollbar as an integer
                                                                        getValue()                           Returns the current value
                                                                                                             of a scrollbar as an integer


© 1999, Pinnacle Software Solutions Inc.                              © 1999, Pinnacle Software Solutions Inc.
Java Programming Guide - Quick Reference                                     Java Programming Guide - Quick Reference

                                                                              Interface method             Description
  setOrientation()                Sets the orientation of a scrollbar
  setValue()                      Sets the current value of a                 actionPerformed()            Invoked whenever an ActionEvent
                                  scrollbar                                                                object is generated (button is
  setMinimum()                    Sets the minimum value of a                                              clicked)
                                  scrollbar
  setMaximum()                    Sets the maximum value of a
                                  scrollbar                                   TextListener interface: Implemented by a class to handle
                                                                              text events. Whenever the text value of a component changes,
                                                                              an interface method called textValueChanged is invoked,
 Frame:                                                                       which must be overridden in the implementing class.

 Constructors                                                                 Interface method             Description

 · Frame() - Creates a new frame without any title                            textValueChanged()           Invoked whenever a Text
 · Frame(String s) - Creates a new frame with the                                                          Event object is generated (text
   specified title                                                                                         value changes)

  Menus:
                                                                              AdjustmentListener interface: Implemented by a class that
  · Can be added only to a frame                                              handles adjustment events. The method
  · A MenuBar instance is first created as:                                   adjustmentValueChanged(), overridden by the
    MenuBar mb = new MenuBar();                                               implementing class is invoked everytime an AdjustmentEvent
  · The MenuBar instance is added to a frame using the                        object occurs (when a scrollbar is adjusted).
    setMenuBar() method of the Frame class as follows:
    setMenuBar(mb);                                                           Interface method                  Description
  · Individual menus are created (instances of the Menu class)                adjustmentValueChanged()          Invoked whenever an
    and added to the menu bar with the add() method                                                             AdjustmentEvent object is
                                                                                                                generated (when a scrollbar
 Dialog: Direct subclass of java.awt.Window, which accepts                                                      thumb is adjusted)
 user input.
                                                                              ItemListener interface: Implemented to handle state change
                                                                              events. The method itemStateChanged()must be overridden
                                                                              by the implementing class.

© 1999, Pinnacle Software Solutions Inc.                                33   © 1999, Pinnacle Software Solutions Inc.                        35




Java Programming Guide - Quick Reference                                     Java Programming Guide - Quick Reference

  Constructors                                                                Method             Description
                                                                              itemStateChanged() Invoked whenever an ItemEvent
 · Dialog(Frame parent, boolean modal) – Creates a                                               object is generated (a checkbox is
   new initially invisible Dialog attached to the frame object                                   checked, an item is selected from a
   parent. The second argument specifies whether the dialog                                      choice menu, or an item is selected
    box is Modal or Non-modal.                                                                   from a list)
 · Dialog (Frame parent, String s, boolean modal)
   – Same as the above. The second argument specifies the title               FocusListener interface: Implemented to receive
   of the dialog box.                                                         notifications whenever a component gains or loses focus. The
                                                                              two methods to be overridden are focusGained() and
  FileDialog: Direct subclass of Dialog, which displays a dialog              focusLost(). The corresponding adapter class is
  window for file selection.                                                  FocusAdapter.

  Constructors                                                                Method                     Description

  · FileDialog(Frame f, String s) - Creates a new                             focusGained()              Invoked whenever a component
    dialog for loading files(file open dialog) attached to the frame                                      gains keyboard focus
    with the specified title                                                  focusLost()                Invoked whenever a component
  · FileDialog(Frame f, String s, int i) - Creates a                                                      loses keyboard focus
    file dialog box with the specified title. The third argument
    specifies whether the dialog is for loading a file or saving a file.
    The value of i can be either FileDialog.LOAD or                           KeyListener interface: Implemented to handle key events.
      FileDialog.SAVE                                                         Each of the three methods – keyPressed(),
                                                                              keyReleased(), keyTyped() – receives a KeyEvent
 AWT Event Listener interfaces: For every AWT event class                     object when a key event is generated.
 there is a corresponding event-listener interface, which is a part
 of the java.awt.event package and provides the event-                        Method                       Description
 handling methods.
                                                                              KeyPressed()                 Invoked whenever a key is
 ActionListener interface: Implemented by a class that                                                      pressed
 handles an action event. The method actionPerformed()
 must be overridden by the implementing class.                                keyReleased()                Invoked whenever a key is
                                                                                                            released


© 1999, Pinnacle Software Solutions Inc.                                     © 1999, Pinnacle Software Solutions Inc.                        36
Java Programming Guide - Quick Reference                                 Java Programming Guide - Quick Reference

  keyTyped()               Invoked whenever a key is typed                windowDeactivated()            Invoked when the window is no
                                                                                                         longer the active window i.e. the
                                                                                                         window can no longer receive
                                                                                                         keyboard events
 MouseListener interface: Implemented by a class handling
 mouse events. It comprises of five methods invoked when a                windowIconified()              Invoked when a normal window is
 MouseEvent object is generated. Its corresponding adapter                                               minimized
 class is the MouseAdapter class.
                                                                          windowDeiconified()            Invoked when a minimized
 Method                   Description                                                                    window is changed to normal
                                                                                                         state
 mouseClicked()           Invoked when mouse is clicked
                          on a component
                                                                          java.sql.Driver interface:    Implemented by every driver
 mouseEntered()           Invoked when mouse enters a                     class.
                          component
                                                                          Methods of the Driver interface:
 mouseExited()            Invoked when mouse exits a
                          component                                       Method                   Description

 mousePressed()           Invoked when mouse button is                    acceptsURL()             Returns a Boolean value indicating
                           pressed on a component                                                  whether the driver can open a
                                                                                                   connection to the specified URL
 mouseReleased()          Invoked when mouse button is
                           released on a component                        connect()                Tries to make a database connection
                                                                                                   to the specified URL

 MouseMotionListener interface: Implemented by a class                    getMajorVersion()        Returns the driver’s major version
 for receiving mouse-motion events. Consists of two methods –                                      number
 mouseDragged() and mouseMoved(), which is invoked
 when a MouseEvent object is generated.                                   getMinorVersion()        Returns the driver’s minor version
 MouseMotionAdapter is its corresponding adapter class.                                            number



© 1999, Pinnacle Software Solutions Inc.                            37   © 1999, Pinnacle Software Solutions Inc.                            39




Java Programming Guide - Quick Reference                                 Java Programming Guide - Quick Reference

                                                                          jdbcCompliant()          Tests whether the driver is a genuine
                                                                          JDBC compliant driver
 Method                   Description
                                                                          java.sql.Connection interface: Represents a session with a
 mouseDragged()           Invoked when the mouse is pressed on            specific database. SQL statements are executed within a session
                          a component and dragged                         and the results are returned.

 mouseMoved()             Invoked when mouse is moved over                Methods of the Connection interface:
                          a component

                                                                          Method                       Description
 WindowListener interface: Implemented by a class to
 receive window events. It consists of seven different methods to         Close()                      Immediately releases the database
 handle the different kinds of window events, which are invoked                                        and JDBC resources
 when a WindowEvent object is generated. Its corresponding
 adapter class is the WindowAdapter class.                                commit()                     Makes all changes since the last
                                                                                                       commit/rollback permanent, and
 Method                        Description                                                             releases the database locks held by
                                                                                                       the connection
 windowOpened()                Invoked when the window is
                               made visible for the first time            createStatement()            Creates and returns a Statement
                                                                                                       object. It is used for sending SQL
 windowClosing()               Invoked when the user attempts                                          statements to be executed on the
                               to close the window from the                                            database
                               Windows system menu
                                                                          getMetaData()                Returns a DatabaseMetaData
 windowClosed()                Invoked when the window has                                             object that represents metadata
                               been closed as a result of calling                                      about the database
                               the dispose() method
                                                                          isReadOnly()                 Checks whether the connection is a
 windowActivated()             Invoked when the window is                                              read-only connection
                               made active i.e. the window can
                               receive keyboard events                    prepareCall()                Creates and returns a
                                                                                                       Callable Statement object,

© 1999, Pinnacle Software Solutions Inc.                            39   © 1999, Pinnacle Software Solutions Inc.                             4
Java Programming Guide - Quick Reference                          Java Programming Guide - Quick Reference


 prepareCall()                 Creates and returns a
                              CallableStatement object
                              (used for calling database stored
                              procedures)
 prepareStatement()           Creates and returns a
                              PreparedStatement
                              object (used for sending
                              precompiled SQL statements to
                              the database)
 rollback()                   Discards all the changes made
                              since the last commit/rollback
                              and releases database locks held
                              by the connection
 setAutoCommit()              Enables or disables the auto
                              commit feature. It is disabled by
                              default

 java.sql.DriverManager class: Responsible for managing a
 set of JDBC drivers. It attempts to locate and load the JDBC
 driver specified by the getConnection() method.

 Methods of the DriverManager class:

 Method                     Description

 getConnection()            Attempts to establish a database
                            connection with the specified
                            database URL, and returns a
                            Connection object

 getLoginTimeout()          Returns the maximum number of
                            seconds a driver can wait when
                            attempting to connect to the
                            database
© 1999, Pinnacle Software Solutions Inc.                          © 1999, Pinnacle Software Solutions Inc.




Java Programming Guide - Quick Reference                          Java Programming Guide - Quick Reference


 registerDriver()           Registers the specified driver with
                            the DriverManager

 setLoginTimeout()          Sets the maximum number of
                            seconds a driver can wait when
                            attempting to connect to the
                            database

 getDrivers()               Returns an enumeration of all the
                            drivers installed on the system

 getDriver()                Returns a Driver object that
                            supports connection through a
                            specified URL




© 1999, Pinnacle Software Solutions Inc.                          © 1999, Pinnacle Software Solutions Inc.

								
To top