package awt;
import java.awt.*;
import java.awt.event.*;
public class ExGui{
         private Frame f;
         private Button b1;
         private Button b2;
         public ExGui(){
             // this.addWindowListener(new WindowAdapter(){public void windowClosing(WindowEvent e){System.exit(0);}});
//这段code放在下面的函数里也不能起到,一点窗口的叉子就关闭窗口的作用。
         }
         private void addWindowListener(WindowAdapter windowAdapter) {
            // TODO Auto-generated method stub
            
        }
        public static void main(String args[]){
                     ExGui that = new ExGui();
                   
                     that.go();
}
          public void go(){
                 f = new Frame("GUI example");
                 f.setLayout(new FlowLayout()); 
                                    //设置布局管理器为FlowLayout
                 b1 = new Button("Press Me"); 
                                    //按钮上显示字符"Press Me"
                 b2 = new Button("Don't Press Me");
                 f.add(b1);
                 f.add(b2);
                 f.pack(); 
                //紧凑排列,其作用相当于setSize(),即让窗口尽量小,小到刚刚能够包容住b1、b2两个按钮
                 
                                  f.setVisible(true);
                  }    
        }
public ExGui(){
  // this.addWindowListener(new WindowAdapter(){public void windowClosing(WindowEvent e){System.exit(0);}});
//这段code放在下面的函数里也不能起到,一点窗口的叉子就关闭窗口的作用。
  }
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你这段代码没有错,我看了,你把this换成f就可以了.