Cardlayout布局管理器编译问题

源代码：
import java.awt.*;
import java.awt.event.*;
public class AWT04 extends Frame {
    Panel p=new Panel();
   
    Button af=new Button("the first");
    Button al=new Button("the last");
    Button an=new Button("next");
    Button ap=new Button("previous");
    Button ag=new Button("search");
    TextField bf=new TextField();
    CardLayout c1=new CardLayout();
    AWT04(){
        this.setTitle("CardLayout 布局 ");
        this.setLayout(null);
        this.add(p);
        p.setLayout(c1);
        for(int j=1;j<=10;j++){
            Button atemp=new Button("Button"+j);
            p.add(atemp,""+j);
        }
        
        p.setBounds(10,40,100,100);
        this.add(af);
        af.addActionListener((ActionListener) this);
        af.setBounds(120,40,60,20);
        this.add(al);
        al.addActionListener((ActionListener) this);
        al.setBounds(120,40,60,20);
        this.add(an);
        an.addActionListener((ActionListener) this);
        an.setBounds(120,40,60,20);
        this.add(ap);
        ap.addActionListener((ActionListener) this);
        ap.setBounds(120,40,60,20);
        this.add(ag);
        ag.addActionListener((ActionListener) this);
        ag.setBounds(120,40,60,20);
        this.add(bf);
        bf.setBounds(20,160,40,20);
        this.setBounds(200,200,400,380);
        this.setVisible(true);
    }
    public void actionPerformed(java.awt.event.ActionEvent e){
        if(e.getSource()==an){
            c1.next(p);
        }
        if(e.getSource()==ap){
            c1.previous(p);
        }
        if(e.getSource()==af){
            c1.first(p);
        }
        if(e.getSource()==al){
            c1.last(p);
        }
        if(e.getSource()==ag){
            c1.show(p,af.getText().trim());
            (af.setText("");
        }
    }
public static void main(String[]args){
    new AWT04();
}
}
//在eclipse编译的时候出错，无法输出。红色字体为程序报错的地方。希望得到解答。
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