Modal dialog in Java example code

In Java, we can create modal dialog so that the main JFrame cannot be operated on until the modal dialog is closed. To achieve this, we need to use one class in Java--JDialog. This class can be used to create an modal dialog.

Example code :

import javax.swing.JDialog;
import javax.swing.JLabel;
import javax.swing.JPanel;

public class Dialog extends JDialog{
    public Dialog(){
        super();
        JPanel panel=new JPanel();
        panel.add(new JLabel("Hello dialog"));
        this.getContentPane().add(panel);
    }
   
    public Dialog(MainFrame mf,String title,boolean modal){
        super(mf,title,modal);
        this.setSize(300,200);
        JPanel panel=new JPanel();
        panel.add(new JLabel("Hello dialog"));
        this.getContentPane().add(panel);
        this.setVisible(true);
    }
}

In the above code, we define a class Dialog which extends the JDialog class in Java. In the second constructor, there are three parameters. JFrame: parent frame,String-title on the dialog, boolean - whether the dialog is modal or non-modal.

The next java code is to demonstrate how to open the Dialog.

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class MainFrame extends JFrame{
    public MainFrame(){
        this.setTitle("Dialog demo");
        this.setSize(400,300);
        this.setLocationRelativeTo(null);
       
        JPanel panel=new JPanel();
        JButton btn=new JButton("Open dialog");
        btn.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent e) {
                new Dialog(MainFrame.this,"Hello",true);
            }
        });
        panel.add(btn);
        this.getContentPane().add(panel);
        this.setVisible(true);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
   
    public static void main(String[] args){
        new MainFrame().setVisible(true);
    }
}

When click on the button on MainFrame, the Dialog will show up and the MainFrame will become non-operable. This can be used when we want to get some information from the dialog before we can continue our operations on the MainFrame.