17.下拉框选择一项，显示对应的图片

  效果：

   

package com.lvshitech.gui;

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.BorderFactory;
import javax.swing.ImageIcon;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

public class JComBoxDemo extends JPanel {
	JLabel picture, text;
	
	public JComBoxDemo() {
		// 字符数组
		String []pStrings = {"cup", "cat", "boy", "girl"};
		
		// ComBox
		JComboBox pList = new JComboBox(pStrings);
		pList.setSelectedIndex(0);
		pList.addActionListener(new PictureSourceActionListener());
		
		// picture
		picture = new JLabel(new ImageIcon("images/" + pStrings[pList.getSelectedIndex()] + ".JPG"));
		picture.setBorder(BorderFactory.createEmptyBorder(10, 0, 0, 0));
		picture.setPreferredSize(new Dimension(180, 140));
		
		// text
		text = new JLabel(pStrings[pList.getSelectedIndex()], JLabel.CENTER);
		
		setLayout(new BorderLayout());
		
		// 添加到容器
		add(pList, BorderLayout.NORTH);
		add(picture, BorderLayout.CENTER);
		add(text, BorderLayout.SOUTH);
		setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20));
	}
	
	public static void main(String[] args) {
		JFrame frame = new JFrame("使用JComBox");
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.add(new JComBoxDemo());
		frame.pack();
		frame.setVisible(true);
	}
	
	private class PictureSourceActionListener implements ActionListener {
		@Override
		public void actionPerformed(ActionEvent e) {
			JComboBox cb = (JComboBox)e.getSource();
			String pName = (String)cb.getSelectedItem();
			picture.setIcon(new ImageIcon("images/" + pName + ".JPG"));
			text.setText(pName);
			text.setHorizontalAlignment(JLabel.CENTER);
		}
	}
}