jcomboboxdemo.java

java课程的资料以及实验的代码

import java.awt.event.*;
import javax.swing.*;
import java.awt.*;
public class JComboBoxDemo extends JFrame implements ItemListener{
  JLabel jl;
  public JComboBoxDemo() {
    Container contentPane = getContentPane();
    contentPane.setLayout(new FlowLayout());

    //定义下拉框，并加入下拉列表元素
		JComboBox jc = new JComboBox();
    jc.addItem("蔬菜");
    jc.addItem("水果");
    jc.addItem("饮料");
    jc.addItemListener(this);
    contentPane.add(jc);

    jl = new JLabel("还未选择内容。");
    contentPane.add(jl);
 	}
 	
  public void itemStateChanged(ItemEvent ie) {
    String s = (String)ie.getItem();
    jl.setText("你选择了"+s);
  }

  public static void main(String[] args){
  	JComboBoxDemo s=new JComboBoxDemo();
  	s.setSize(300,150);
  	s.setVisible(true);
  }
}