Java/GWT/ChangeListener

Listen to ChangeListener

package com.jexp.gwt.client;
import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.client.ui.Button;
import com.google.gwt.user.client.ui.ClickListener;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.user.client.ui.Widget;
import com.google.gwt.user.client.ui.ChangeListener;
import com.google.gwt.user.client.ui.ListBox;
public class GWTClient implements EntryPoint,ChangeListener {
  ListBox list = new ListBox();
  public void onModuleLoad() {
    
    list.setVisibleItemCount(10);
    list.setMultipleSelect(true);
    list.addItem("A");
    list.addItem("B");
    list.addItem("C");
    list.addItem("D");
    
    list.addChangeListener(this);
    RootPanel.get().add(list);
  }
  public void onChange(Widget sender) {
    if (sender == list) {
      Window.alert(Integer.toString(list.getSelectedIndex()));
    }
  }  
}