java - How to close child jFrames automatically when i close the parent? -

i have parent jframe , 2 'child' jframes in package jframe. imagine open parent jframe , it's child jframes - 3 forms open. close parent jframe.

what should close child frames automatically after close parent jframe?
here code:

class parent:
public class parent extends jframe {

public parent() {      jbutton child1 = new jbutton("child1");     child1.addactionlistener(new actionlistener() {         @override         public void actionperformed(actionevent e) {             new child1().setvisible(true);;         }     });      jbutton child2 = new jbutton("child2");     child2.addactionlistener(new actionlistener() {         @override         public void actionperformed(actionevent e) {             new child2().setvisible(true);         }     });     jbutton closealljframe = new jbutton("closealljframe");     closealljframe.addactionlistener(new actionlistener() {         @override         public void actionperformed(actionevent e) {             dispose();         }     });      this.setbounds(500, 200, 400, 200);     this.addwindowlistener(new windowadapter() {         @override         public void windowclosing(windowevent e) {             dispose();         }     });     jpanel jpanel = new jpanel();     jpanel.add(child1);     jpanel.add(child2);     jpanel.add(closealljframe);     this.add(jpanel); }  @override public void dispose() {     super.dispose(); }  public static void main(string[] args) {     new parent().setvisible(true); }}   

class child1:

public class child1 extends jframe {

public child1() {     this.setbounds(200, 300, 300, 200);     this.settitle("child 1"); }} 

class child2:

public class child2 extends jframe {

public child2() {     this.setbounds(200, 300, 300, 200);     this.settitle("child 1"); }} 

add window listener frame implements windowclosed(windowevent e) method javadoc windowlistener