此程序的作用是。选择下拉菜单里面的国家。并在两个地方显示国旗和国家介绍。但怎么不能显示。为了测试。我只添加了中国

package countrymessage;import java.awt.BorderLayout;
import java.awt.Dimension;import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JLabel;
import java.awt.*;
import javax.swing.JComboBox;
import javax.swing.JTextArea;
import javax.swing.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;/**
 * <p>Title: </p>
 *
 * <p>Description: </p>
 *
 * <p>Copyright: Copyright (c) 2008</p>
 *
 * <p>Company: </p>
 *
 * @author not attributable
 * @version 1.0
 */
public class CountryMessageFrame extends JFrame {
    JPanel contentPane;
    JLabel jLabel1 = new JLabel();
    JComboBox jComboBox1 = new JComboBox();
    JLabel jLabel2 = new JLabel();
    JLabel jLabel3 = new JLabel();
    JTextArea jTextArea1 = new JTextArea();
    JButton jButton1 = new JButton();
    JLabel jLabel4 = new JLabel();
    public CountryMessageFrame() {
        try {
            setDefaultCloseOperation(EXIT_ON_CLOSE);
            jbInit();
        } catch (Exception exception) {
            exception.printStackTrace();
        }
    }    /**
     * Component initialization.
     *
     * @throws java.lang.Exception
     */
    private void jbInit() throws Exception {
        contentPane = (JPanel) getContentPane();
        contentPane.setLayout(null);
        setSize(new Dimension(400, 400));
        setTitle("国家信息");
        jLabel1.setFont(new java.awt.Font("Dialog", Font.PLAIN, 16));
        jLabel1.setText("国家(地区)名:");
        jLabel1.setBounds(new Rectangle(43, 40, 108, 40));
        jComboBox1.setFont(new java.awt.Font("Dialog", Font.PLAIN, 16));
        jComboBox1.setBounds(new Rectangle(160, 51, 123, 33));
        jComboBox1.addItem("");
        jComboBox1.addItem("中国");
        jComboBox1.addItem("日本");
        jComboBox1.addItem("美国");
        jComboBox1.addItem("埃及");
        jComboBox1.addItem("韩国");
        jLabel2.setFont(new java.awt.Font("Dialog", Font.PLAIN, 16));
        jLabel2.setText("国旗");
        jLabel2.setBounds(new Rectangle(43, 115, 75, 29));
        jLabel3.setFont(new java.awt.Font("Dialog", Font.PLAIN, 16));
        jLabel3.setText("信息");
        jLabel3.setBounds(new Rectangle(207, 115, 75, 29));
        jTextArea1.setBounds(new Rectangle(207, 150, 145, 90));
        jButton1.setBounds(new Rectangle(156, 256, 87, 35));
        jButton1.setFont(new java.awt.Font("Dialog", Font.PLAIN, 16));
        jButton1.setText("显示");
        jButton1.addActionListener(new
                                   CountryMessageFrame_jButton1_actionAdapter(this));
        jLabel4.setBounds(new Rectangle(15, 145, 182, 101));
        contentPane.add(jLabel1);
        contentPane.add(jComboBox1);
        contentPane.add(jLabel2);
        contentPane.add(jLabel3);
        contentPane.add(jTextArea1);
        contentPane.add(jButton1);
        contentPane.add(jLabel4);
    }    public void jButton1_actionPerformed(ActionEvent e) {
        String country=jComboBox1.getToolTipText();
        if(country!=null){
            if(country=="中国"){
                jTextArea1.setText("中国是一个富饶的国家");
                jLabel4.setIcon(new ImageIcon("D:\\study\\java\\10\\work\\p232\\CountryMessage\\pic\\China.jpg"));
            }
        }
    }
}
class CountryMessageFrame_jButton1_actionAdapter implements ActionListener {
    private CountryMessageFrame adaptee;
    CountryMessageFrame_jButton1_actionAdapter(CountryMessageFrame adaptee) {
        this.adaptee = adaptee;
    }    public void actionPerformed(ActionEvent e) {
        adaptee.jButton1_actionPerformed(e);
    }
}