Re: Confused about refere

  To: comp.lang.java.gui
jamestechinfo@yahoo.com wrote:


It seems like an X-Y problem to me.

To use your example of a ComboBox of prespecified window sizes, the
ComboBox shouldn't care about it's top-level container. Whatever class
instantiates the ComboBox should wire it up to do the resizing.

Here's an SSCCE (use Google if you don't know about SSCCE)

---------------------------8<---------------------------------
import java.awt.Dimension;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.util.ArrayList;
import java.util.List;

import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class WindowSizer {

     public static void main(String[] args) {
         SwingUtilities.invokeLater(new Runnable() {
             public void run() {
                 new WindowSizer();
             }
         });
     }

     WindowSizer() {

         final JFrame f = new JFrame("Window Sizer");

         List<Dimension> sizes = new ArrayList<Dimension>();
         sizes.add(new BoxableDimension(320,240));
         sizes.add(new BoxableDimension(640,480));
         sizes.add(new BoxableDimension(800,600));

         JComboBox box = new JComboBox(sizes.toArray());
         box.addItemListener(new ItemListener() {
             public void itemStateChanged(ItemEvent e) {
                 if (e.getStateChange() == ItemEvent.SELECTED) {
                     f.setSize((Dimension) e.getItem());
                 }
             }});

         JPanel p = new JPanel();
         p.add(box);

         f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         f.add(p);
         f.pack();
         f.setLocationRelativeTo(null);
         f.setVisible(true);
     }

     /*
      * To make Dimension useful in a JComboBox we override toString()
      * to return the sort of String we want to see in the JComboBox.
      */
     class BoxableDimension extends Dimension {
         BoxableDimension(int width, int height) {
             super(width, height);
         }
         public String toString() {
             return height + " x " + width;
         }
     }

}
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