【例 11-6】小应用程序先将若干个按钮和若干个标签放入JPanel中,然后将JPanel放入JScrollPane中,最后,将JScrollPane放入小程序的窗口中,程序所创建的JScrollPane总是带水平和垂直滚动条,滚动面板的可视范围小于面板的实际要求,可以移动滚动条的滑块显示面板原先不在可视范围内的区域。 import java.applet.*; import javax.swing.*; import java.awt.*; class MyWindow extends JFrame{ public MyWindow(int w,int h){ setTitle("滚动面板实例"); Container con=getContentPane(); con.setPreferredSize(new Dimension(w,h)); con.setLayout(new BorderLayout()); JPanel p=new JPanel(); p.setLayout(new GridLayout(6,6)); for (int i=0;i<6;i++){ p.add(new JLabel()); for(int j=1;j<=2;j++){ p.add(new JButton("按钮"+(2*i+j))); p.add(new JLabel("标签"+(2*i+j))); } p.add(new JLabel()); } p.setBackground(Color.blue); p.setPreferredSize(new Dimension(w+60,h+60)); JScrollPane ScrollPane=new JScrollPane(p); ScrollPane.setPreferredSize(new Dimension(w-60,h-60)); add(ScrollPane,BorderLayout.CENTER);//小程序添加滚动面板 setVisible(true); pack(); } } class ScrollPane extends JScrollPane{ public ScrollPane(Component p){ super(p); setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS); setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS); } } public class J506 extends Applet{ MyWindow myWindow; public void init(){ myWindow=new MyWindow(400,350); } }