divisiondemosecondversion.java

java编程代码

import java.util.Scanner;

public class DivisionDemoSecondVersion
{
   public static void main(String[] args)
   {
        Scanner keyboard = new Scanner(System.in);

        try
        {
           System.out.println("Enter numerator:"); 
           int numerator = keyboard.nextInt();
           System.out.println("Enter denominator:"); 
           int denominator = keyboard.nextInt();

           double quotient = safeDivide(numerator, denominator);
           System.out.println(numerator + "/" 
                                     + denominator 
                                     + " = " + quotient);
        }
        catch(DivisionByZeroException e)
        {
            System.out.println(e.getMessage( ));
            secondChance( );
        }

        System.out.println("End of program.");
   }


   public static double safeDivide(int top, int bottom) 
                             throws DivisionByZeroException
   {
       if (bottom == 0)
           throw new DivisionByZeroException( );

       return top/(double)bottom;
   }

   public static void secondChance( )
   {
        Scanner keyboard = new Scanner(System.in);

        try
        {
           System.out.println("Enter numerator:"); 
           int numerator = keyboard.nextInt();
           System.out.println("Enter denominator:"); 
           int denominator = keyboard.nextInt();

           double quotient = safeDivide(numerator, denominator);
           System.out.println(numerator + "/" 
                                     + denominator 
                                     + " = " + quotient);
        }
        catch(DivisionByZeroException e)
        {
           System.out.println("I cannot do division by zero.");
           System.out.println("Aborting program.");
           System.exit(0);
        }
    }
}