Java 7 resize a JFrame (my GUI): the componentListener is not getting fired

问题

I've Googled around and could not find an answer:

I have a JFrame as a GUI and set a componentListener like

this.addComponentListener(new CL(this, logger));

In the componentListener I have the componentResized, etc...

public void componentResized(ComponentEvent e) {
    if (e.getSource() == gui) {
       here I do the code
    }
}

Everything is working fine under Java 6, but under Java 7, the Jframe is being resized but is not being repainted: the component listener is not getting called

I tried some alternatives from StackOverflow in the way of coding, but no way to make it work.

When I minimize the GUI window and restore it, then "componentResized" is being called.

Anyone an idea what's going on and why it works under Java 6 and not Java 7.

Here is a sample code:

public class Frame extends JFrame {
    private JPanel  panel;
    public Frame() {
        super();
        getContentPane().setBounds(new Rectangle(0, 0, 200, 200));
        getContentPane().setLayout(null);
        getContentPane().add(getPanel());
        this.addComponentListener(new ComponentListener() {
            @Override
            public void componentResized(ComponentEvent e) {
                System.out.println("Window Resized: Frame");}
            @Override
            public void componentMoved(ComponentEvent e) {}
            @Override
            public void componentShown(ComponentEvent e) {}
            @Override
            public void componentHidden(ComponentEvent e) {}});
        this.setSize(200, 200);
        this.setPreferredSize(new Dimension(200, 200));
        this.pack();
    }
    public JPanel getPanel() {
        if (panel == null) {
            panel = new JPanel();
            panel.setBackground(Color.RED);
            panel.setBounds(0, 0, 200, 200);
            panel.setPreferredSize(new Dimension(200, 200));
        }
        return panel;
    }
}

And this is the startup class:

public class StartUp {
    public static void main(String[] args) {
        try {
            UIManager.setLookAndFeel(UIManager.getCrossPlatformLookAndFeelClassName());
        } catch (Exception e) {
            e.printStackTrace();
        }
        Frame app = new Frame();
        app.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
        app.pack();
        app.setVisible(true);
    }
}

When run under Java 6 you get the "Window Resized: Frame" message.
The same run under Java 7, no messages at all.

Below are 2 links to Pictures:

Java 6

Java 6 Frame Image

Java 7

Java 7 Frame Image

回答1:

your code (before balast removed, changed to standard) work for me correctly
ComponentListener firing an event from every pixels
this is basic property of componentResized(), otherwise required SwingTimer.restart() untill resize ended)

balast removed, changed to standard

import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;

public class MyFrame {

    private JFrame frame = new JFrame();
    private JPanel panel;

    public MyFrame() {
        frame.add(getPanel());
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.setVisible(true);
        frame.addComponentListener(new ComponentAdapter() {
            @Override
            public void componentResized(ComponentEvent e) {
                System.out.println("Window Resized: Frame");
            }
        });
    }

    public JPanel getPanel() {
        if (panel == null) {
            panel = new JPanel() {
                @Override
                public Dimension getPreferredSize() {
                    return new Dimension(300, 200);
                }
            };
            panel.setBackground(Color.RED);
        }
        return panel;
    }

    public static void main(String[] args) {
        try {
            UIManager.setLookAndFeel(UIManager.getCrossPlatformLookAndFeelClassName());
        } catch (Exception e) {
            e.printStackTrace();
        }
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                MyFrame app = new MyFrame();
            }
        });
    }
}

来源：https://stackoverflow.com/questions/18697046/java-7-resize-a-jframe-my-gui-the-componentlistener-is-not-getting-fired

标签

java

swing

resize

jframe

componentlistener