Block ComboBox Example
// Example from http://www.crionics.com/products/opensource/faq/swing_ex/SwingExamples.html
/* (swing1.1) */
import java.awt.Component;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.util.Vector;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.JSeparator;
import javax.swing.ListCellRenderer;
import javax.swing.UIManager;
import javax.swing.border.EmptyBorder;
/**
* @version 1.0 12/25/98
*/
public class BlockComboBoxExample extends JFrame {
final String SEPARATOR = "SEPARATOR";
public BlockComboBoxExample() {
super("Block ComboBox Example");
String[][] str = { { "A", "B", "C" }, { "1", "2", "3" },
{ "abc", "def", "ghi" } };
JComboBox combo = new JComboBox(makeVectorData(str));
combo.setRenderer(new ComboBoxRenderer());
combo.addActionListener(new BlockComboListener(combo));
getContentPane().setLayout(new FlowLayout());
getContentPane().add(combo);
setSize(300, 100);
setVisible(true);
}
private Vector makeVectorData(String[][] str) {
boolean needSeparator = false;
Vector data = new Vector();
for (int i = 0; i < str.length; i++) {
if (needSeparator) {
data.addElement(SEPARATOR);
}
for (int j = 0; j < str[i].length; j++) {
data.addElement(str[i][j]);
needSeparator = true;
}
}
return data;
}
public static void main(String args[]) {
try {
UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
} catch (Exception evt) {}
BlockComboBoxExample frame = new BlockComboBoxExample();
frame.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
}
class ComboBoxRenderer extends JLabel implements ListCellRenderer {
JSeparator separator;
public ComboBoxRenderer() {
setOpaque(true);
setBorder(new EmptyBorder(1, 1, 1, 1));
separator = new JSeparator(JSeparator.HORIZONTAL);
}
public Component getListCellRendererComponent(JList list, Object value,
int index, boolean isSelected, boolean cellHasFocus) {
String str = (value == null) ? "" : value.toString();
if (SEPARATOR.equals(str)) {
return separator;
}
if (isSelected) {
setBackground(list.getSelectionBackground());
setForeground(list.getSelectionForeground());
} else {
setBackground(list.getBackground());
setForeground(list.getForeground());
}
setFont(list.getFont());
setText(str);
return this;
}
}
class BlockComboListener implements ActionListener {
JComboBox combo;
Object currentItem;
BlockComboListener(JComboBox combo) {
this.combo = combo;
combo.setSelectedIndex(0);
currentItem = combo.getSelectedItem();
}
public void actionPerformed(ActionEvent e) {
String tempItem = (String) combo.getSelectedItem();
if (SEPARATOR.equals(tempItem)) {
combo.setSelectedItem(currentItem);
} else {
currentItem = tempItem;
}
}
}
}
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