Exersice 121 Number format Exercise 129 Listing 79 Calcula

Exersice 12.1

(Number format )

Exercise 12.9

* 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).

Answer Calculator.java

First part with try and catch block :

Program :

import java.util.*;

/*Class Calulator*/
public class Calculator{
   /*Main method*/
   public static void main(String args[]){
       /*if(args.length !=3){
           System.out.println(\"Please input properly : operand 1 operator operand 2\");
           System.exit(0);
        }*/
       int no1 = 0;
       int no2 = 0;
       int answer = 0;
/*checking numer*/
   try{
       no1 = Integer.parseInt(args[0]);
   }catch(Exception e){
       System.out.println(\"Invalid Input : \" + args[0]);
   }
   try{
       no2 = Integer.parseInt(args[2]);
   }catch(Exception e){
       System.out.println(\"Invalid Input : \" + args[2]);
   }
/*if exception occur than catch will be executed*/
switch(args[1]){
case \"+\" :
   System.out.println(\"Answer is : \" + (no1+no2));
   break;

case \"-\" :
   System.out.println(\"Answer is : \" + (no1-no2));
   break;
case \"*\" :
   System.out.println(\"Answer is : \" + (no1*no2));
   break;
case \"/\" :
   System.out.println(\"Answer is : \" + (no1/no2));
   break;
default :
   System.out.println(\"Invalid Input\");
   break;
}
}
}

Sample Output :
c:\\example>java calculator \"4+7\"
Answer is : 11
c:\\example>java calculator \"9*6\"
Answer is : 54
c:\\example>java calculator \"8-3\"
Answer is : 5
c:\\example>java calculator \"e-4\"
Invalid operand : e

First part without try and catch block :

Program :

import java.util.*;
import java.util.regex.Pattern.*;

/*Class Calulator*/
public class Calculator{
/*boolean checking method*/
public static boolean isNumeric(String s){
return java.util.regex.Pattern.matches(\"\\\\d+\",s);
}

   /*Main method*/
   public static void main(String args[]){
       /*if(args.length !=3){
           System.out.println(\"Please input properly : operand 1 operator operand 2\");
           System.exit(0);
        }*/
       int no1 = 0;
       int no2 = 0;
       int answer = 0;
       boolean check = true;
/*checking numer*/
   check = isNumeric(args[0]);
   if(check ==false){
       System.out.println(\"Invalid Input :\" + args[0]);
   }
   else{
       no1 = Integer.parseInt(args[0]);
   }
   check = isNumeric(args[2]);
   if(check ==false){
       System.out.println(\"Invalid Input :\" + args[2]);
   }
   else{
       no1 = Integer.parseInt(args[0]);
   }

switch(args[1]){
case \"+\" :
   System.out.println(\"Answer is : \" + (no1+no2));
   break;

Exersice 12.1 (Number format ) Exercise 12.9 * Listing 7.9, Calculator.java, is a simple commandline calculator. * Note that the program terminates if any opera

Exersice 121 Number format Exercise 129 Listing 79 Calcula

Solution

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