How do I get the JFrame of a component?

By Wayan Saryada in Java Swing 0 Comment

This demo give an example on how to get the JFrame of a component. In this example we try to get the JFrame from a button action listener event. To get the JFrame we utilize the SwingUtilities.getRoot() method and this will return the root component of the component tree in out small program below which is a JFrame

Beside getting the JFrame, in this program we also do small stuff like changing the frame background color by a random color every time a user presses the Change Frame Color button.

package org.kodejava.example.swing;

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

public class GetFrameDemo extends JFrame {
    public GetFrameDemo() throws HeadlessException {
        initialize();
    }

    private void initialize() {
        this.setSize(400, 100);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        this.setLayout(new FlowLayout(FlowLayout.CENTER));

        final JLabel rLabel = new JLabel("r: ");
        final JLabel gLabel = new JLabel("g: ");
        final JLabel bLabel = new JLabel("b: ");

        JButton button = new JButton("Change Frame Color");
        button.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                Component component = (Component) e.getSource();

                //
                // Returns the root component for the current component tree
                //
                JFrame frame = (JFrame) SwingUtilities.getRoot(component);

                int r = (int) (Math.random() * 255);
                int g = (int) (Math.random() * 255);
                int b = (int) (Math.random() * 255);
                
                rLabel.setText("r: " + r);
                gLabel.setText("g: " + g);
                bLabel.setText("b: " + b);

                frame.getContentPane().setBackground(new Color(r, g, b));
            }
        });

        this.getContentPane().add(button);
        this.getContentPane().add(rLabel);
        this.getContentPane().add(gLabel);
        this.getContentPane().add(bLabel);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                new GetFrameDemo().setVisible(true);
            }
        });
    }
}

Wayan Saryada

Programmer, runner, recreational diver, currently living in the island of Bali, Indonesia. Mostly programming in Java, creating web based application with Spring Framework, Hibernate / JPA.

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