Line wrapping and scrolling in JPanel

Question

Hello,
I've got an empty JPanel to which I want to add an (unknown) number of JLabels. Each JLabel has a text which is just one word. When my program is adding JLabels to the JPanel, I want it to have the same behaviour as a normal text editor: when a line is full, the next line gets filled (line wrapping).
If I just keep adding JLabels to a JPanel of a fixed size with .add(), there's no line wrapping. I tried it by giving the JPanel a fixed size, flowLayout and nesting it within a JScrollPane, but it keeps filling one long line, instead of jumping to the next one.
Any obvious solutions??
Thanks
Mark

Answer 1

well this depends on how your layout is build, you should post some code so we can see what your trying to do.
For example if your JPanel is the Frame's main panel, fixing a MaximumSize or PreferredSize wont have any effect, it will grow as big as you defined the JFrame size.
If you have only a JPanel with a max size of 200,300 in a JFrame with a size of 800,600, it will grow to 800,600.
You could create a BoxLayout with X axis, then insert an HorizontalStruts, insert your JPanel and another Horizontal Struts(Box.createHorizontalStrut(int width) ) to force the JPanel to be smaller than the JFrame.
I did not test this a lot, but it seams to work
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Test {
  public static MyFrame frame ;
  public static void main(String[] args) {
    frame = new MyFrame();
    frame.show(true);
    frame.pack();
  public static class MyFrame extends JFrame {
    JLabel a, b, c, d, e, f, g, h, i, j, k ;
    public MyFrame(){
      super();
      JPanel sizeLimiter = (JPanel)this.getContentPane();
      sizeLimiter.setLayout(new BoxLayout(sizeLimiter, BoxLayout.X_AXIS));
     // sizeLimiter.setPreferredSize(new Dimension(800,600));
      JPanel mainPanel = new JPanel();
      mainPanel.setLayout(new FlowLayout());
      mainPanel.setPreferredSize(new Dimension(400,300));
      mainPanel.setMinimumSize(new Dimension(400,300));
      a = new JLabel("this is sample test ");
      b = new JLabel("to demonstrate an example ");
      c = new JLabel("of simple a flow layout ");
      d = new JLabel("which is wrapping ");
      e = new JLabel("when it reaches the end ");
      f = new JLabel("of a line. ");
      g = new JLabel("Set the maximum size of the panel ");
      h = new JLabel("And it should work ");
      i = new JLabel("If it doesnt post your code so we can");
      j = new JLabel("check it out to see whats wrong ");
      k = new JLabel("sincerly yours, Jf Beaulac ");
      mainPanel.add(a);
      mainPanel.add(b);
      mainPanel.add(c);
      mainPanel.add(d);
      mainPanel.add(e);
      mainPanel.add(f);
      mainPanel.add(g);
      mainPanel.add(h);
      mainPanel.add(i);
      mainPanel.add(j);
      mainPanel.add(k);
      // Fix some "margins"
      sizeLimiter.add(Box.createHorizontalStrut(200));
      // Squeeze the panel
      sizeLimiter.add(mainPanel);
      sizeLimiter.add(Box.createHorizontalStrut(200));
    protected void processWindowEvent(WindowEvent e) {
      super.processWindowEvent(e);
      if (e.getID() == WindowEvent.WINDOW_CLOSING) {
        this.dispose();
}Regards,
Jf Beaulac