Best books about JAVA programming:

• Head First JAVA, Second Editon
• Effective Java Programming Language Guide
• Professional Java, JDK 5 Edition
• Ivor Horton's Beginning Java 2, JDK 5 Edition

JAVA JComboBox

This example shows how to ajust jcombobox width according to its list item's length.It includes 2 files: SteppedComboBoxExample.java and SteppedComboBox.java

import java.awt.*;
import java.util.*;
import javax.swing.*;
import javax.swing.plaf.metal.*;
import javax.swing.plaf.basic.*;

class SteppedComboBoxUI extends MetalComboBoxUI {
protected ComboPopup createPopup() {
BasicComboPopup popup = new BasicComboPopup( comboBox ) {

public void show() {
Dimension popupSize = ((SteppedComboBox)comboBox).getPopupSize();
popupSize.setSize( popupSize.width,
getPopupHeightForRowCount( comboBox.getMaximumRowCount() ) );
Rectangle popupBounds = computePopupBounds( 0,
comboBox.getBounds().height, popupSize.width, popupSize.height);
scroller.setMaximumSize( popupBounds.getSize() );
scroller.setPreferredSize( popupBounds.getSize() );
scroller.setMinimumSize( popupBounds.getSize() );
list.invalidate();
int selectedIndex = comboBox.getSelectedIndex();
if ( selectedIndex == -1 ) {
list.clearSelection();
} else {
list.setSelectedIndex( selectedIndex );
}
list.ensureIndexIsVisible( list.getSelectedIndex() );
setLightWeightPopupEnabled( comboBox.isLightWeightPopupEnabled() );

show( comboBox, popupBounds.x, popupBounds.y );
}
};
popup.getAccessibleContext().setAccessibleParent(comboBox);
return popup;
}
}


public class SteppedComboBox extends JComboBox {
protected int popupWidth;

public SteppedComboBox(ComboBoxModel aModel) {
super(aModel);
setUI(new SteppedComboBoxUI());
popupWidth = 0;
}

public SteppedComboBox(final Object[] items) {
super(items);
setUI(new SteppedComboBoxUI());
popupWidth = 0;
}

public SteppedComboBox(Vector items) {
super(items);
setUI(new SteppedComboBoxUI());
popupWidth = 0;
}


public void setPopupWidth(int width) {
popupWidth = width;
}

public Dimension getPopupSize() {
Dimension size = getSize();
if (popupWidth < 1) popupWidth = size.width;
return new Dimension(popupWidth, size.height);
}
}