CODEWITHSUNDEEP
javaswing
Jonas Olesen
Jonas Olesen

Reputation: 568

Add JPanels dynamically to either a JTable or a JScrollPane

Currently working on a project and I need to add a panel I've made to a scrollpane or a table dynamically. The scrollpane should start out empty and add the panels.

The GuiConstructor is where i make the window.

My problem is that if I don't comment out the setSize in the GuiConstructor, the window starts out very small. Secondly, when i press the add button, it doesn't add the panels.

public GuiConstructor(){
    super(APPLICATION_NAME);
    setLayout(new BorderLayout());
    LoopControlWindow loopwin = new LoopControlWindow(connect);
    add(loopwin , BorderLayout.NORTH);
    pack();
    setLocationRelativeTo(null);
    setResizable(false);
    setVisible(true);
    //this.setSize(500, 500);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);


}


public class LoopControlWindow extends JPanel {

IConnector connect;

public LoopControlWindow(IConnector connect) {
    super(new BorderLayout());
    this.connect = connect;
    initPane();
}

private void initPane() {
    JPanel panel = new JPanel(new GridLayout(3,1));
    FolderSearchComp fsc = new FolderSearchComp(connect);
    JScrollPane scrollPane = new JScrollPane();
    JButton button = new JButton("Add");

    button.addActionListener(new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent e) {
            panel.add(new FolderSearchComp(connect));
            scrollPane.getViewport().setView(panel);
        }
    });



    scrollPane.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));
    scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
    scrollPane.setViewportBorder(new LineBorder(Color.BLACK));


    add(scrollPane, BorderLayout.CENTER);
    add(button, BorderLayout.SOUTH);


}

Upvotes: 0

Views: 271

Answers (2)

Dodd10x
Dodd10x

Reputation: 3349

For your first problem, you need to specify a size for the initial JFrame(). One way is to call setSize as you are doing. Another is to override getPreferredSize() to return the default size. And one other option is to find the size of the user's monitor and set the JFrame to be a percentage of that size. That way you can ensure your window always fits on your user's screen.

    int height = GraphicsEnvironment.getLocalGraphicsEnvironment()
            .getDefaultScreenDevice().getDefaultConfiguration().
            getBounds().height;
    height = (int) (height * .85);
    int width = GraphicsEnvironment.getLocalGraphicsEnvironment()
            .getDefaultScreenDevice().getDefaultConfiguration().
            getBounds().width;
    width = (int) (width * .85);
    frame.setSize(width, height);

Second, you need to call revalidate() and repaint() anytime you add or remove from a layout in order to see the changes. 

button.addActionListener(new ActionListener() {

    @Override
    public void actionPerformed(ActionEvent e) {
        panel.add(new FolderSearchComp(connect));
        scrollPane.getViewport().setView(panel);
        revalidate();
        repaint();
    }
});

One note on border layout. The components in it will not resize with your JFrame. Whatever component that is placed in BorderLayout.CENTER will, however. That component will grow to fill all extra space as the JFrame grows. It will also be the component that shrinks when the JFrame windows gets smaller.

Upvotes: 0

markbernard
markbernard

Reputation: 1420

This is typical of this style of GUI app. You need to tell the layout manager how big to make the Window initialy without using setSize(). The way to do this is to override getPreferredSize() to return a default size. In your case:

public LoopControlWindow extends JPanel {
    private Dimension size;

    public LoopControlWindow() {
        Preferences prefs = Preferences.userNodeForPackge("your.java.package");
        size = new Dimension(prefs.getInt("width", 800), prefs.getInt("height", 600));
    }
    public Dimension getPreferredSize() {
        return size;
    }
}

By doing it this way you can store the user preferences for the window dimensions but also provide sensible defaults to start.

You should also make sure that this JPanel is your main panel and is added to the JFrame at BorderLayout.CENTER to ensure that your window gets drawn properly. All other panels should be somewhere inside this one.

Once you have this set up calling pack() will work correctly.

Upvotes: 2

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