//例4.11
import java.awt.*;
import java.awt.event.*;
import java.applet.*;
public class tt extends Applet implements ActionListener
{  
   Label L1,L2;
   TextField tf1,tf2;
   String answerStr;
   double d1,d2;
   public void init()
   {
   	  L1=new Label("請輸入0到100間的整數"); add(L1);
   	  tf1=new TextField(6); add(tf1);
   	  tf2=new TextField(6); add(tf2);
   	  L2=new Label(""); add(L2);
   	  tf1.addActionListener(this); tf2.addActionListener(this);
   }
   public void actionPerformed(ActionEvent evt)
   {
   	 try
   	 {
   	   d1=Double.parseDouble(tf1.getText());//可能異常
   	   d2=Double.parseDouble(tf2.getText());//可能異常
   	   L2.setText("兩數相除的結果："+Result());//可能異常
     }
     catch(NumberFormatException e)
     {
       answerStr="輸入的必須是數字";
       L2.setText(answerStr);	
     }
     catch(NumberRangeException e)
     {
       answerStr=e.getMessage(); L2.setText(answerStr);
     }
     repaint();
   }
   public double Result() throws NumberRangeException
   {
   	 double answer=0;
   	 try
   	 {  
   	   if((d1<0)||(d1>100)||(d2<0)||(d2>100))
   	   {
   	   	 String ss="輸入的數不在指定的范圍，請重新輸入。";
   	   	 NumberRangeException ee=new NumberRangeException(ss);
   	   	 throw ee;
   	   }
   	   answer=d1/d2;	
   	 }
   	 catch(ArithmeticException e)
   	 { answerStr=e.toString(); }
   	 return answer;
   }
} 
class NumberRangeException extends Exception
{
  NumberRangeException(String msg) {super(msg); }
}