import java.awt.event.*;
import java.awt.*;
import javax.swing.JOptionPane;
class Dwindow extends Frame implements ActionListener
{  TextField inputNumber;
   TextArea  save;
   Dwindow(String s)
   {  super(s);
      inputNumber=new TextField(22);inputNumber.addActionListener(this);
      save=new TextArea();
      add(inputNumber,BorderLayout.NORTH); add(save,BorderLayout.CENTER); 
      setBounds(60,60,300,300); setVisible(true);
      validate();
      addWindowListener(new WindowAdapter()
                      {   public void windowClosing(WindowEvent e)
                           { System.exit(0);
                           }
                      }
                   );
   }
   public void actionPerformed(ActionEvent e) 
   {  String s=inputNumber.getText();
      int n=0;
     if ( n<=1000)
      {  save.append("\n"+s);
      }  
      else 
      {int m=JOptionPane.showConfirmDialog(this,"输入数字已经大于1000,是否继续将该数字放入文本区","提示",
                                               JOptionPane.YES_NO_OPTION );
      if(m==JOptionPane.YES_OPTION)  
        {  save.append("\n"+s);
        }  
      else if(m==JOptionPane.NO_OPTION)  
       { inputNumber.setText(null);
       }  
      } 
      
   }
}
public class Example16_4
{  public static void main(String args[]) 
   {  new Dwindow("带对话框的窗口");
   }
}
 就是输入大于1000的数,弹出提示:输入数字已经大于1000,是否继续将该数字放入文本区。求大侠指点,我先谢了!