exceptionapplet.java

Java语言是目前最流行

import java.awt.*;
import java.awt.event.*;
import java.applet.*;

public class ExceptionApplet extends Applet implements ActionListener
{
	Label L1,L2;
	TextField tf1,tf2;
	String answerStr;
	double d1,d2;
	
	public void init()
	{
		L1 = new Label("请输入0到100之间的整数");
		add(L1);
		tf1 = new TextField(6);
		add(tf1);
		tf2 = new TextField(6);
		add(tf2);
		L2 = new Label("两数相除的结果：");
		add(L2);
		tf1.addActionListener(this);
		tf2.addActionListener(this);	
	}	
	public void actionPerformed(ActionEvent evt)
	{
		try
		{
			d1 = Double.valueOf(tf1.getText()).doubleValue();
			d2 = Double.valueOf(tf2.getText()).doubleValue();
			//valueOf(String s)可能抛出异常NumberFormatException
			L2.setText("两数相除的结果:"+Result());
			//调用Result（）方法可能会抛出NumberRangException异常			
		}	
		catch(NumberFormatException e)
		{
			answerStr = "输入的必须是数字";	
			L2.setText(answerStr);
		}
		catch(NumberRangException ee)
		{
			answerStr = ee.getMessage();
			L2.setText(answerStr);	
		}
		repaint();
	}
	public double Result() throws NumberRangException
	{
		double answer = 0;
		try
		{
			if((d1<0)||(d2<0)||(d1>100)||(d2>100))
			{
				NumberRangException ee = new NumberRangException("输入的数字不在指定的范围！请从新输入");	
				throw ee;
			}	
			answer = d1/d2;
		}	
		catch(ArithmeticException eee)
		{
			answerStr = eee.toString();	
		}
		return answer;
	}
}
class NumberRangException extends Exception
{
	NumberRangException(String msg)
	{
		super(msg);	
	}	
	//子类调用父类带参数的构造函数
}