Question

I am running into a problem with GridBagLayouts.

I have a few components laid out as shown in the picture below:

I want the “center” component to be able to move above the bottom edge of “top-right” if the “top” component shrinks small enough. However, this obviously causes a problem since it would have to be in a different row in the grid to be able to do so.

To solve this – I define the entire right column as its own container, with its own layout manager. I’d expect the two columns to be able to behave independently, however I get the same problem! I don’t see how the two layout managers could possibly be interacting still. Can anyone possibly explain what my problem is?

Here is the relevant code (in my class extending Applet):

public void init(){
    addComponents();
}

private void addComponents(){
    setLayout(new GridBagLayout());
    GridBagConstraints c = new GridBagConstraints();

    Left left = new Left();
    Top top = new Top();
    Center center = new Center();
    TopRight topRight = new TopRight();
    BottomRight bottomRight = new BottomRight();
    Bottom bottom = new Bottom();

    topRight.setPreferredSize(new Dimension(200,200));
    top.setPreferredSize(new Dimension(0,200));
    center.setPreferredSize(new Dimension(0,100));
    container.setPreferredSize(new Dimension(200,200));

    c.fill = GridBagConstraints.BOTH;

    c.gridx = 0; c.gridy = 0;
    c.gridwidth = 1; c.gridheight = 3;
    c.weightx = 0.2; c.weighty = 1.0;
    this.add(left,c);

    c.gridx = 1; c.gridy = 0;
    c.gridwidth = 1; c.gridheight = 1;
    c.weightx = 0.8; c.weighty = 0.8;
    this.add(top,c);

    c.gridx = 1; c.gridy = 1;
    c.gridwidth = 1; c.gridheight = 1;
    c.weightx = 0.8; c.weighty = 0.0;
    this.add(center,c);

    c.gridx = 1; c.gridy = 2;
    c.gridwidth = 1; c.gridheight = 1;
    c.weightx = 0.8; c.weighty = 0.2;
    this.add(bottom,c);

    JPanel container = new JPanel();
    container.setLayout(new GridBagLayout());

    c.gridx = 2; c.gridy = 0;
    c.gridwidth = 1; c.gridheight = 3;
    c.weightx = 0.0; c.weighty = 1.0;
    this.add(container,c);

    GridBagConstraints c2 = new GridBagConstraints();
    c2.fill = GridBagConstraints.BOTH;

    c2.gridx = 0; c2.gridy = 0;
    c2.gridwidth = 1; c2.gridheight = 1;
    c2.weightx = 0.0; c2.weighty = 0.0;
    container.add(topRight,c2);

    c2.gridx = 0; c2.gridy = 1;
    c2.gridwidth = 1; c2.gridheight = 1;
    c2.weightx = 0.0; c2.weighty = 1.0;
    container.add(bottomRight,c2);
}

Note: Each of the components shown (left, top, etc) is an extension of JPanel – each with its paint(Graphics g) method overridden to fill it with some color.

Thanks in advance, and sorry for the long read,

Jonathan

Answer 1

I fixed the problem. It had something to do with me setting the preferred height of the Top component unnecessarily – when I removed that line it worked like I was wanting.