JComboBox组合框练习

package javademo;
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
public class combobox extends JFrame{
	protected Container container;
	protected JComboBox colorcb;
	protected JPanel top;
	protected JTextField inf;
	protected JLabel ll;
	protected String colorSelected;
	public combobox() {
		container=this.getContentPane();
		ll=new JLabel("请选择颜色");
		colorcb=new JComboBox();//颜色检索下拉列表
		colorcb.addItem("");
		colorcb.addItem("红色");
		colorcb.addItem("绿色");
		colorcb.addItem("蓝色");
		colorcb.addItemListener(new ColorSelectedListener());//注册事件监听者
		inf=new JTextField(15);
		top=new JPanel();
		top.setLayout(new FlowLayout(FlowLayout.LEFT));
		top.add(ll);
		top.add(colorcb);
		top.add(inf);
		this.add(BorderLayout.NORTH,top);
		this.setTitle("JComboBox演示程序");
		this.setSize(600,450);
		this.show();
	}
	class ColorSelectedListener implements ItemListener{
		public void itemStateChanged(ItemEvent event) {
			if( event.getStateChange()==ItemEvent.SELECTED) {
				colorSelected=(String)colorcb.getSelectedItem();
				inf.setText("你选择的颜色是"+colorSelected);
		}
	}
	}
	public static void main(String []args) {
		new combobox();
	}
}

　　运行结果：