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by Dinesh Thakur

It is a subclass of the abstract InputEvent class and is generated when the user presses or releases a key or does both i.e. types a character.

When a key is pressed, the event generated is KEY_PRESSED

When a key is released, the event generated is KEY_RELEASED

When a character is typed on the keyboard, that is a key is pressed and then released, the event generated is KEY_TYPED

Following are the types of methods provided by KeyEvent class

int getKeyCode()    It is used for getting the integer code associated with a key. It is used for KEY_PRESSED and   KEY_RELEASED events. The keycodes are defined as constants in KeyEvent class

char getKeyChar()      This method is used to get the Unicode character of the key pressed. It works with the KEY_TYPED events

 

import java.applet.Applet;

import java.awt.*;
import java.awt.event.*;
/* <APPLET CODE ="KeyboardEvents.class" WIDTH=300 HEIGHT=200> </APPLET> */
public class KeyboardEvents extends Applet implements KeyListener
  {
      TextArea tpress,trel;
      TextField t;
      public void init()
        {
           t=new TextField(20);
           t.addKeyListener(this);
           tpress=new TextArea(3,70);
           tpress.setEditable(false);
           trel=new TextArea(3,70);
           trel.setEditable(false);
           add(t);
           add(tpress);
           add(trel);
        }
           public void keyTyped(KeyEvent e)
             {
                disppress(e,"Key Typed:");
             }
                public void keyPressed(KeyEvent e)
                  {
                    disppress(e,"KeyPressed:");
                  }
                     public void keyReleased(KeyEvent e)
                     {
                        String charString,keyCodeString,modString;
                        char c=e.getKeyChar();
                        int keyCode=e.getKeyCode();
                        int modifiers=e.getModifiers();
                        charString="Key character='"+c+"'";
                        keyCodeString="key code="+keyCode+"("+KeyEvent.getKeyText(keyCode)+")";
                        modString="modifiers="+modifiers;
                        trel.setText("Key released"+charString+keyCodeString+modString);
                     }
                        protected void disppress(KeyEvent e,String s)
                           {
                              String charString,keyCodeString,modString,tmpString;
                              char c=e.getKeyChar();
                              int keyCode=e.getKeyCode();
                              int modifiers=e.getModifiers();
                              if(Character.isISOControl(c))
                                {
                                   charString="key character=(an unprintable control character)";
                                }
                                   else
                                    {
                                      charString="key character='"+c+"'";
                                    }
                                      modString="modifiers="+modifiers;
                                      tmpString=KeyEvent.getKeyModifiersText(modifiers);                                                                      
                                                                if(tmpString.length()>0)
                                           {
                                              modString+="("+tmpString+")";
                                           }
                                              else
                                                {
                                                   modString+="(no modifiers)";
                                                }
                                                   keyCodeString="key code="+keyCode+"("+KeyEvent.getKeyText(keyCode)+")";
                                                                                   tpress.setText(s+charString+keyCodeString+modString);
                        }
  }               

Keyboard Events in Java Example