Question

I’m using two frames. In the first frame I have a button to open the second frame. In the second frame there is also a button, but this one is for closing the second frame. But I don’t know how to do this, and I’m looking for some help to solve this?

GUI1

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class GUI1 extends JFrame implements ActionListener{
JButton btn1;
Container contentPane;
public GUI1()
{
    setTitle("GUI 1");
    setResizable(false);
    setSize(600,300);
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    contentPane = getContentPane();
    contentPane.setLayout(new FlowLayout());
    btn1 = new JButton("Open GUI 2 frame");
    contentPane.add(btn1);
    btn1.setFocusable(false);
    btn1.addActionListener(this);
}
public void actionPerformed(ActionEvent event){
    if(event.getSource() == btn1)
    {
        GUI2 frame2 = new GUI2();
        frame2.setVisible(true);
    }
}
public static void main(String[] args) {
    GUI1 frame = new GUI1();
    frame.setVisible(true);
}
}

GUI2

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class GUI2 extends JFrame implements ActionListener {
Container contentPane;
JButton btn2;
public GUI2()
{
    setTitle("GUI 2");
    setResizable(false);
    setSize(400,200);
    setDefaultCloseOperation(DISPOSE_ON_CLOSE);
    contentPane = getContentPane();
    contentPane.setLayout(new FlowLayout());
    btn2 = new JButton("Close GUI 2 frame");
    contentPane.add(btn2);
    btn2.addActionListener(this);
}
public void actionPerformed(ActionEvent event){
    if(event.getSource() == btn2)
    {
        // Close GUI2 ??
    }
}
}

Answer 1

Simply call dispose() in the listener:

public void actionPerformed(ActionEvent event){
    if(event.getSource() == btn2)
    {
        dispose();
    }

Also, by clicking X, this will dispose the window since you have set the defaultCloseOperator(DISPOSE_ON_CLOSE);