问题描述
package other;import java.awt.*; import java.awt.event.*; import javax.swing.*; public class CardLayoutDemo implements ActionListener{ JPanel p1,p2,p3,p4; int i=1; JFrame f; public CardLayoutDemo(){ f=new JFrame();//当做top-level组件 Container contentPane=f.getContentPane(); contentPane.setLayout(new GridLayout(2,1)); p1=new JPanel(); Button b=new Button("Change Card"); b.addActionListener(this);//当按下"Change Card"时，进行事件监听，将会有系统操作产生。 p1.add(b); contentPanedfsdfsdsd://处理操作在52-64行.不报错 什么意思啊*************************************** contentPane.add(p1); p2=new JPanel(); p2.setLayout(new FlowLayout()); p2.add(new JButton("first")); p2.add(new JButton("second")); p2.add(new JButton("third")); p3=new JPanel(); p3.setLayout(new GridLayout(3,1)); p3.add(new JButton("fourth")); p3.add(new JButton("fifth")); p3.add(new JButton("This is the last button")); p4=new JPanel(); p4.setLayout(new CardLayout()); p4.add("one",p2); p4.add("two",p3); /*要显示CardLayout的卡片，除了用show(Container parent,String name)这个方法外 *，也可试试first(Container),next(Container),previous(Container),last(Container)这 *四个方法，一样可以达到显示效果。 */ ((CardLayout)p4.getLayout()).show(p4,"one"); contentPane.add(p4); f.setTitle("CardLayout"); f.pack(); f.setVisible(true); f.addWindowListener( new WindowAdapter(){ public void windowClosing(WindowEvent e){ System.exit(0); } } ); } public void actionPerformed(ActionEvent event){ switch(i){ case 1: ((CardLayout)p4.getLayout()).show(p4,"two"); break; case 2: ((CardLayout)p4.getLayout()).show(p4,"one"); break; } i++; if (i==3) i=1; f.validate(); } public static void main(String[] args){ new CardLayoutDemo(); } }
解决方案
contentPanedfsdfsdsd:相当于在你程序里加了个标记，这个标记名就是contentPanedfsdfsdsd 。和C++里面 用于goto 语句时加的标记一样。