import java.applet.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.event.ActionEvent;class Example12 extends Applet implements ActionListener{
CardLayout mycard;
Button button1,button2,button3;
Mycanvas mycanvas[];
Panel p;
public void init();
{
setLayout(new BorderLayout());
mycard=new CardLayout();
p=new Panel();
p.setLayout(mycard);
button1=new Button("first");
button2=new Button("next");
button3=new Button("last one");
mycanvas=new Mycanvas[21];
for(int i=1;i<=20;i++){
mycanvas[i] = new Mycanvas(i,i);
p.add("I am"+i,mycanvas[i]);
}
button1.addActionListener(this);
button2.addActionListener(this);
button3.addActionListener(this);
Panel p2=new Panel();
p2.add(button1);p2.add(button2);p2.add(button3);
add(p,BorderLayout.CENTER);add(p2,BorderLayout.SOUTH);
}
public void actionPerfromed(ActionEvent e){
if(e.getSource()==button1){
mycard.first(p);
}
else if(e.getSource()==button2){
mycard.next(p);
}
else if(e.getSource()==button3){
mycard.last(p);
}
} public void actionPerformed(ActionEvent actionEvent) {
}
}
import java.applet.*;
import java.awt.*;
import java.awt.event.*;
public class Mycanvas extends Canvas{
int x,y;
Mycanvas(int a,int b){
x=a;y=b;
setSize(100,160);
}
public void paint(Graphics g){
g.setColor(Color.red);
g.fillOval(50,50,4*x,4*y);
g.drawString("I AM A"+x,10,150);
}
}
编译时为什么说程序未初始化??那位能帮我下,谢谢!
F:\>appletviewer Example12.java
载入:Example12.class 不是 public 对象或没有公共构造函数。你可以将public 关键字添加进去就可以正常运行