学步园

//:ComboBoxText.java
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JComboBox;
import javax.swing.JFrame;

public class ComboBoxText {
private String[][] xxx = {
{"浙江","杭州","温州","绍兴","舟山",},
{"江苏","南京","无锡","徐州","蒙眬",},
{"上海","闵行区","普陀区","金山区",},
};

private Object[] a(){
Object[] os = new Object[xxx.length];
for(int i=0; i<xxx.length; i++){
os[i]=xxx[i][0];
}
return os;
}

private Object[] b(Object a){
for(int i=0; i<xxx.length; i++){
if(xxx[i][0].equals(a)){
	Object[] o = new Object[xxx[i].length-1];
	for(int j=0; j<o.length; j++)
	o[j]=xxx[i][j+1];
	return o;
}
}
return new Object[]{};
}

public static void main(String[] args) {
final ComboBoxText ct = new ComboBoxText();
final JComboBox ca = new JComboBox(ct.a());
final JComboBox cb = new JComboBox();
ca.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e) {
	cb.removeAllItems();
	Object selected = ca.getSelectedItem();
	Object[] newItems = ct.b(selected);
	for(int i=0; i<newItems.length; i++)
	cb.addItem(newItems[i]);
}
});
ca.setSelectedIndex(-1);
JFrame f = new JFrame();f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.getContentPane().setLayout(new FlowLayout(FlowLayout.LEFT));
f.add(ca);f.add(cb);f.setVisible(true);
f.setSize(200,100);
}
}