How to press combination key using java Robot class ???

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COMPLETE SOURCE CODE FOR : PressCombinationKeyUsingRobot.java
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import java.awt.Robot;

import java.awt.event.KeyEvent;

public class PressCombinationKeyUsingRobot
{
 public static void main(String[]args)
 {
  //Combination Alt+F4 is a window close order in windows operating system
  //How to implement combination of Alt and F4 in using Robot class
  
  try
  {
   Robot a=new Robot();
   a.keyPress(KeyEvent.VK_ALT);
   a.keyPress(KeyEvent.VK_F4);
   a.keyRelease(KeyEvent.VK_ALT);
   a.keyRelease(KeyEvent.VK_F4);
  }
  catch(Exception exception)
  {
   exception.printStackTrace();
  }
 }
}

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JUST COMPILE AND EXECUTE IT
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