How to Make a Jframe Modal in Swing Java

You can create a class that is passed a reference to the parent JFrame and holds it in a JFrame variable. Then you can lock the frame that created your new frame.

parentFrame.disable();

//Some actions

parentFrame.enable();

just replace JFrame to JDialog in class

public class MyDialog extends JFrame // delete JFrame and write JDialog

and then write setModal(true); in constructor

After that you will be able to construct your Form in netbeans and the form becomes modal

1. Create a new JPanel form
2. Add your desired components and code to it

YourJPanelForm stuff = new YourJPanelForm();
JOptionPane.showMessageDialog(null,stuff,"Your title here bro",JOptionPane.PLAIN_MESSAGE);

Your modal dialog awaits...

As far as I know, JFrame cannot do Modal mode. Use JDialog instead and call setModalityType(Dialog.ModalityType type) to set it to be modal (or not modal).

If you're prepared to use a JDialog instead of a JFrame, you can set the ModalityType to APPLICATION_MODAL.

This provides identical behaviour to your typical JOptionPane:

import java.awt.event.ActionEvent;
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionListener;

public class MyDialog extends JFrame {

public MyDialog() {
    setBounds(300, 300, 300, 300);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setVisible(true);
    setLayout(new FlowLayout());
    JButton btn = new JButton("TEST");
    add(btn);
    btn.addActionListener(new ActionListener() 
    {

        @Override
        public void actionPerformed(ActionEvent e) {
            showDialog();
        }
    });
}

private void showDialog() 
{

    JDialog dialog = new JDialog(this, Dialog.ModalityType.APPLICATION_MODAL);
    //OR, you can do the following...
    //JDialog dialog = new JDialog();
    //dialog.setModalityType(Dialog.ModalityType.APPLICATION_MODAL);

    dialog.setBounds(350, 350, 200, 200);
    dialog.setVisible(true);
}

public static void main(String[] args) 
{
    new MyDialog();
}
}

This static utility method shows a modal JFrame by secretly opening a modal JDialog, too. I used this successfully and with proper behavior on Windows 7, 8, and 10-with-multiple-desktops.

It's a nice example for the very rarely used feature of local classes.

import javax.swing.*;
import java.awt.Dialog;
import java.awt.Dimension;
import java.awt.Frame;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

// ... (class declaration)

/**
 * Shows an already existing JFrame as if it were a modal JDialog. JFrames have the upside that they can be
 * maximized.
 * <p>
 * A hidden modal JDialog is "shown" to effect the modality.
 * <p>
 * When the JFrame is closed, this method's listener will pick up on that, close the modal JDialog, and remove the
 * listener.
 *
 * made by dreamspace-president.com
 *
 * @param window the JFrame to be shown
 * @param owner  the owner window (can be null)
 * @throws IllegalArgumentException if argument "window" is null
 */
public static void showModalJFrame(final JFrame window, final Frame owner) {

    if (window == null) {
        throw new IllegalArgumentException();
    }
    window.setModalExclusionType(Dialog.ModalExclusionType.APPLICATION_EXCLUDE);
    window.setVisible(true);
    window.setAlwaysOnTop(true);

    final JDialog hiddenDialogForModality = new JDialog(owner, true);
    final class MyWindowCloseListener extends WindowAdapter {
        @Override
        public void windowClosed(final WindowEvent e) {
            window.dispose();
            hiddenDialogForModality.dispose();
        }
    }

    final MyWindowCloseListener myWindowCloseListener = new MyWindowCloseListener();
    window.addWindowListener(myWindowCloseListener);

    final Dimension smallSize = new Dimension(80, 80);
    hiddenDialogForModality.setMinimumSize(smallSize);
    hiddenDialogForModality.setSize(smallSize);
    hiddenDialogForModality.setMaximumSize(smallSize);
    hiddenDialogForModality.setLocation(-smallSize.width * 2, -smallSize.height * 2);
    hiddenDialogForModality.setVisible(true);
    window.removeWindowListener(myWindowCloseListener);
}

The only code that have worked for me:

childFrame.setAlwaysOnTop(true);

This code should be called on the main/parent frame before making the child/modal frame visible. Your child/modal frame should also have this code:

parentFrame.setFocusableWindowState(false);
this.mainFrame.setEnabled(false);

What I've done in this case is, in the primary jframe that I want to keep visible (for example, a menu frame), I deselect the option focusableWindowState in the property window so It will be FALSE. Once that is done, the jframes I call don´t lose focus until I close them.

As others mentioned, you could use JDialog. If you don't have access to the parent frame or you want to freeze the hole application just pass null as a parent:

final JDialog frame = new JDialog((JFrame)null, frameTitle, true); frame.setModal(true);
frame.getContentPane().add(panel);
frame.setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
frame.pack();
frame.setVisible(true);

There's a bit of code that might help:

import java.awt.Component;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;

public class ModalJFrame extends JFrame {

    Object currentWindow = this;

    public ModalJFrame() 
    {
        super();
        super.setTitle("Main JFrame");
        super.setSize(500, 500);
        super.setResizable(true);
        super.setLocationRelativeTo(null);

        JMenuBar menuBar = new JMenuBar();
        super.setJMenuBar(menuBar);

        JMenu fileMenu = new JMenu("File");
        JMenu editMenu = new JMenu("Edit");

        menuBar.add(fileMenu);
        menuBar.add(editMenu);

        JMenuItem newAction = new JMenuItem("New");
        JMenuItem openAction = new JMenuItem("Open");
        JMenuItem exitAction = new JMenuItem("Exit");
        JMenuItem cutAction = new JMenuItem("Cut");
        JMenuItem copyAction = new JMenuItem("Copy");
        JMenuItem pasteAction= new JMenuItem("Paste");

        fileMenu.add(newAction);
        fileMenu.add(openAction);
        fileMenu.addSeparator();
        fileMenu.add(exitAction);

        editMenu.add(cutAction);
        editMenu.add(copyAction);
        editMenu.addSeparator();
        editMenu.add(pasteAction);

        newAction.addActionListener(new ActionListener()
        {
            public void actionPerformed(ActionEvent arg0)
            {

                JFrame popupJFrame = new JFrame();

                popupJFrame.addWindowListener(new WindowAdapter()
                {
                      public void windowClosing(WindowEvent e) 
                      {
                          ((Component) currentWindow).setEnabled(true);                     }
                      });

                ((Component) currentWindow).setEnabled(false);
                popupJFrame.setTitle("Pop up JFrame");
                popupJFrame.setSize(400, 500);
                popupJFrame.setAlwaysOnTop(true);
                popupJFrame.setResizable(false);
                popupJFrame.setLocationRelativeTo(getRootPane());
                popupJFrame.setVisible(true);
                popupJFrame.setDefaultCloseOperation(JFrame.HIDE_ON_CLOSE);
            }
        });

        exitAction.addActionListener(new ActionListener()
        {
            public void actionPerformed(ActionEvent arg0)
            {
                System.exit(0);
            }
        });
    }
    public static void main(String[] args) {

        ModalJFrame myWindow = new ModalJFrame();
        myWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        myWindow.setVisible(true);
    }
}

not sure the contetns of your JFrame, if you ask some input from users, you can use JOptionPane, this also can set JFrame as modal

            JFrame frame = new JFrame();
            String bigList[] = new String[30];

            for (int i = 0; i < bigList.length; i++) {
              bigList[i] = Integer.toString(i);
            }

            JOptionPane.showInputDialog(
                    frame, 
                    "Select a item", 
                    "The List", 
                    JOptionPane.PLAIN_MESSAGE,
                    null,
                    bigList,
                    "none");
            }