*12.1 (NumberFormatException) Listing 7.9, Calculator.java, is a simple commandl

Question

*12.1 (NumberFormatException) Listing 7.9, Calculator.java, is a simple commandline
calculator. Note that the program terminates if any operand is nonnumeric.
Write a program with an exception handler that deals with nonnumeric operands;
then write another program without using an exception handler to achieve the
same objective. Your program should display a message that informs the user of
the wrong operand type before exiting (see Figure 12.12).

Calculator.java

package chapter7;

public class Calculator {
/** Main method */
public static void main(String[] args) {
// Check number of strings passed
if (args.length != 3) {
System.out.println(
"Usage: java Calculator operand1 operator operand2");
System.exit(0);
}

// The result of the operation
int result = 0;

// Determine the operator
switch (args[1].charAt(0)) {
case '+': result = Integer.parseInt(args[0]) +
Integer.parseInt(args[2]);
break;
case '-': result = Integer.parseInt(args[0]) -
Integer.parseInt(args[2]);
break;
case '.': result = Integer.parseInt(args[0]) *
Integer.parseInt(args[2]);
break;
case '/': result = Integer.parseInt(args[0]) /
Integer.parseInt(args[2]);
}

// Display result
System.out.println(args[0] + ' ' + args[1] + ' ' + args[2]
+ " = " + result);
}
}

Command Prompt C:lexercise jaua Exercise13 1 45 34 please use java Exercise13.1 operand1 operator operand2 Cilexercioo java Exercioe13.1 45 34 5+34 79 C:lexercise jaua Exercise13.1 4/534 rong Input: 4/5 C:lexercise

Explanation / Answer

program with exception handler

program without exception handler:

package NFE2;

import java.util.Scanner;

public class Calculator {
    /** Main method */
    public static void main(String[] args){
        String num1;
        String num2;
        String operation;

        Scanner input = new Scanner(System.in);
        System.out.println("Please enter number1");
        num1 = input.next();
    int i = Integer.parseInt(num1);
   
        System.out.println("Please enter second number");
        num2 = input.next();
        int j = Integer.parseInt(num2);

       
        // Check number of strings passed
    if (i != (int) i || j != (int) j ){
            System.out.println("wrong input");
            System.exit(0);
        }else{

            Scanner op = new Scanner(System.in);

            System.out.println("Please enter operation");

            operation = op.next();


            if (operation.equals("+")){

                System.out.println("your answer is " + (i + j));
            }
            if (operation.equals("-"))
            {
                System.out.println("your answer is " + (i - j));
            }
            if (operation.equals("/"))
            {
                System.out.println("your answer is " + (i / j));
            }
            if (operation .equals( "*"))
            {
                System.out.println("your answer is " + (i * j));
            }
        }
    }
}

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