exce3.java

Java异常

//自定义一个定义异常
import java.lang.*;
import java.io.*;

 class NumberRangeException extends Exception
{
	public NumberRangeException()
	{
		super();
		}
	public NumberRangeException(String s)
	{
		super(s);
		}
}

public  class Exce3{
	public static void main(String args[])
	{
		int num1,num2,sum;
		String s="";
		try
		{
			System.out.print("请键入第一个数字：");
			BufferedReader in1=new BufferedReader(new InputStreamReader(System.in));
			s=in1.readLine();
			num1=Integer.parseInt(s);
			
			System.out.print("请键入第二个数字：");
			BufferedReader in2=new BufferedReader(new InputStreamReader(System.in));
			s=in2.readLine();
			num2=Integer.parseInt(s);
			System.out.println("两数和为："+sum(num1,num2));
			
			}
		catch(NumberRangeException e)
		{
			System.out.println(e.getMessage());
			}  
		catch(IOException e){}
	}
public static int sum(int num1,int num2) throws NumberRangeException
{
	if((num1<0)||(num1>1000)||(num2<0)||(num2>1000))
	{
		throw(new NumberRangeException("键入的数字必须在0～1000之内！"));
		}
	return num1+num2;
}
}