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.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.SwingUtilities;
import javax.swing.WindowConstants;
import java.awt.Color;
import java.awt.Component;
import java.awt.FlowLayout;
import java.awt.HeadlessException;

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

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

    private void initialize() {
        this.setSize(400, 100);
        this.setDefaultCloseOperation(WindowConstants.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 Background Color");
        button.addActionListener(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);
    }
}

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Wayan

Founder at Kode Java Org

I am a programmer, a runner, a recreational diver, currently live in the island of Bali, Indonesia. Mostly programming in Java, Spring Framework, Hibernate / JPA. If these posts help, you can support me, buy me a cup of coffee or tea. Thank you 🥳

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