Problem with GridBagLayout and panels

Question

So what I'm trying to do is:

I am using grid layout, and here is what I still have:

public class board { public static void addComponentsToPane(Container pane) { pane.setLayout(new GridBagLayout()); GridBagConstraints c = new GridBagConstraints(); JPanel leftTop = new JPanel(); leftTop.setPreferredSize(new Dimension(251,300)); leftTop.setBackground(Color.black); c.fill = GridBagConstraints.HORIZONTAL; c.gridx = 0; c.gridy = 0; pane.add(leftTop, c); JPanel middleTop = new JPanel(); middleTop.setPreferredSize(new Dimension(251,200)); middleTop.setBackground(Color.green); c.fill = GridBagConstraints.HORIZONTAL; c.gridx = 1; c.gridy = 0; pane.add(middleTop, c); JPanel rightTop = new JPanel(); rightTop.setPreferredSize(new Dimension(251,600)); rightTop.setBackground(Color.blue); c.fill = GridBagConstraints.HORIZONTAL; c.gridx = 2; c.gridy = 0; pane.add(rightTop, c); JPanel leftBottom = new JPanel(); leftBottom.setPreferredSize(new Dimension(251,300)); leftBottom.setBackground(Color.red); c.fill = GridBagConstraints.HORIZONTAL; c.gridx = 0; c.gridy = 1; pane.add(leftBottom, c); JPanel middleBottom = new JPanel(); middleBottom.setPreferredSize(new Dimension(251,400)); middleBottom.setBackground(Color.yellow); c.fill = GridBagConstraints.HORIZONTAL; c.gridx = 1; c.gridy = 1; pane.add(middleBottom, c); } private static void createAndShowGUI() { JFrame frame = new JFrame("GridBagLayoutDemo"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); addComponentsToPane(frame.getContentPane()); frame.pack(); frame.setVisible(true); } public static void main(String[] args) { javax.swing.SwingUtilities.invokeLater(new Runnable() { public void run() { createAndShowGUI(); } }); } } 

It creates something like:

How would I press the panels so that they touch each other, as in the first picture. I looked at GridBagConstraints, but I could not find anything like this to work. Thanks!

Answer 1

Instead of solving the problem of a full layout with one layout manager, it is often easier to post layouts. For example, your sample code can be modified to use a horizontal grid (so that the columns are equal in width - I really don't know if you want to force this. If not, then FlowLayout or BoxLayout will be better), and the columns use BoxLayout each:

 import java.awt.Color; import java.awt.Container; import java.awt.Dimension; import java.awt.GridLayout; import javax.swing.BoxLayout; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.SwingUtilities; public class board { public static void addComponentsToPane(Container pane) { pane.setLayout(new GridLayout(1, 0)); JPanel left = new JPanel(); pane.add(left); left.setLayout(new BoxLayout(left, BoxLayout.Y_AXIS)); JPanel leftTop = new JPanel(); leftTop.setPreferredSize(new Dimension(125, 150)); leftTop.setBackground(Color.black); left.add(leftTop); JPanel leftBottom = new JPanel(); leftBottom.setPreferredSize(new Dimension(125, 150)); leftBottom.setBackground(Color.red); left.add(leftBottom); JPanel middle = new JPanel(); pane.add(middle); middle.setLayout(new BoxLayout(middle, BoxLayout.Y_AXIS)); JPanel middleTop = new JPanel(); middleTop.setPreferredSize(new Dimension(125, 100)); middleTop.setBackground(Color.green); middle.add(middleTop); JPanel middleBottom = new JPanel(); middleBottom.setPreferredSize(new Dimension(125, 200)); middleBottom.setBackground(Color.yellow); middle.add(middleBottom); JPanel right = new JPanel(); right.setPreferredSize(new Dimension(125, 300)); right.setBackground(Color.blue); pane.add(right); } private static void createAndShowGUI() { JFrame frame = new JFrame("GridBagLayoutDemo"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); addComponentsToPane(frame.getContentPane()); frame.pack(); frame.setVisible(true); } public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { @Override public void run() { createAndShowGUI(); } }); } } 

Results in:

(I changed the preferred sizes a bit to reduce the image. As an additional note, it is usually better to override getPreferredSize () rather than using setPreferredSize () ; setPreferredSize () is convenient for a quick example, though)