//test9_7import java.awt.BorderLayout;import java.awt.Button;import java.awt.Container;import java.awt.GridLayout;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import javax.swing.ImageIcon;import javax.swing.JFrame;import javax.swing.JLabel;import javax.swing.JOptionPane;import javax.swing.JPanel;import javax.swing.JScrollPane;import javax.swing.ScrollPaneConstants;public class test9_7 extends JFrame implements ActionListener {    private JPanel jPanel; //左边panel框    private Button button1;    private Button button2;    private Button button3;    private JScrollPane jscrollPane; //右边滚动框    private JLabel label; //滚动框中的标签    public ImageIcon picture = null; //标签中的图标    public boolean whetherCroll = true; //用于切换滚动条的显示    public void init() {        JFrame jFrame = new JFrame("练习使用JscrollPane");        Container pane = jFrame.getContentPane();        this.setDefaultCloseOperation((JFrame.EXIT_ON_CLOSE));        // 定义左边镶板JPanel框和三个按钮        jPanel = new JPanel(new GridLayout(3, 1, 0, 30));        button1 = new Button("滚动");        button1.addActionListener(this);        button2 = new Button("试试");        button2.addActionListener(this);        button3 = new Button("退出");        button3.addActionListener(this);        jPanel.add(button1);        jPanel.add(button2);        jPanel.add(button3);        // 读取图片作为图标        picture = new ImageIcon("D:/image/fuck.jpg/");        // 将图标赋给标签label        label = new JLabel(picture);        // 定义滚动框,总是显示滚动条        jscrollPane = new JScrollPane(label,                ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS,                ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS);        // 将左右两边的中间容器放弃JFrame中        pane.add(jPanel, BorderLayout.WEST);        pane.add(jscrollPane, BorderLayout.EAST);        //排版显示        jFrame.pack();        jFrame.setVisible(true);    }    @Override    public void actionPerformed(ActionEvent e) {        // TODO Auto-generated method stub        if (e.getActionCommand() == "滚动") {            if (whetherCroll) {                jscrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_NEVER); //垂直不显示                jscrollPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_NEVER); //水平不显示                whetherCroll = false;            } else {                jscrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS); //垂直显示                jscrollPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS); //水平显示                whetherCroll = true;            }        }        if (e.getActionCommand() == "试试") {            JOptionPane.showMessageDialog(this,                "oh,,,Fuck your teacher? yeal……good!");        }        if (e.getActionCommand() == "退出") {            System.exit(0);        }    }    public static void main(String[] args) {        new test9_7().init();    }}运行结果：显示滚动条[img=544x369]17afc72b1af3187.png[/img]点击“滚动”按钮后，没显示滚动条[img=542x371]17afc730208ce69.png[/img]