CODEWITHSUNDEEP
javacalculator
user10681171
user10681171

Reputation:

Simple calculator in java

I'm trying to create simple calculator in java with user input for first number and second number and then with while loop calculate as user like but when I wrote for example a instead of sum two number it broke loop!! why?

package com.myproject.CalcEngine2;
import java.util.Scanner; // import the Scanner class

public class Main {

    public static void main(String[] args) {
        Scanner myObj = new Scanner(System.in);
        System.out.println("Enter fisr number");
        double val1 = myObj.nextDouble();
        System.out.println("Enter fisr number");
        double val2 = myObj.nextDouble();
        double result = 0.0d;
        String addition = "a";
        System.out.println("Enter what you want to do");
        String opCode = myObj.next();
        while(opCode.equals("E")) {
            if (opCode.equals(addition))
                result = val1 + val2;
            else if (opCode.equals("s"))
                result = val1 - val2;
            else if (opCode.equals("d"))
                result = val1 / val2;
            else if (opCode.equals("m"))
                result = val1 * val2;
            System.out.println(result);
            System.out.println("Enter what you want to do"+"E for exit , a for addition , s for subtraction , d for Division , m for multiplication ");
            opCode = myObj.next();
        }
    }
}

program shows for every char that I wrote it will be false but I can't understand why!?

Upvotes: 0

Views: 1939

Answers (4)

user10681171
user10681171

Reputation:

Thanks all And here you are final code for who will search in future with remove case sensitivity!

package com.myprogram.CalcEngine;
import java.util.Scanner; // import the Scanner class

public class Main {

    public static void main(String[] args) {
        Scanner myObj = new Scanner(System.in);
        System.out.println("Enter fisr number");
        double val1 = myObj.nextDouble();
        System.out.println("Enter fisr number");
        double val2 = myObj.nextDouble();
        double result = 0.0d;
        String addition = "a";
        System.out.println("Enter what you want to do");
        String opCode = myObj.next().toLowerCase();
        while(!opCode.equals("e")) {
            if (opCode.equals(addition)){
                result = val1 + val2;
                System.out.println(result);}
            else if (opCode.equals("s")){
                result = val1 - val2;
                System.out.println(result);}
            else if (opCode.equals("d")){
                result = val1 / val2;
                System.out.println(result);}
            else if (opCode.equals("m")){
                result = val1 * val2;
                System.out.println(result);}
            else
                System.out.println("Error please enter true character: ");
            System.out.println("Enter what you want to do"+"E for exit , a for addition , s for subtraction , d for Division , m for multiplication ");
            opCode = myObj.next();
        }
        System.out.println("Good bye! See you :) ");
    }
}

with change

String opCode = myObj.next();

to 

String opCode = myObj.next().toLowerCase();

in line 15 and change

opCode = myObj.next();

to 

opCode = myObj.next().toLowerCase();

in line 32

All the input will be lowercase. All the best.

Upvotes: 0

Finn is missing
Finn is missing

Reputation: 47

Please check the condition in the while loop, it terminates if the entered input is not 'E'.

To make it work change as follows:

while(!opCode.equals("E")) {
// Operation code
}

BTW, to be more clear with the operations, you can print as below:

System.out.println("Enter what you want to do, 'a': for addition, 's': for subtraction, 'd': for division, 'm': for multiplication ");

Upvotes: 0

Lakshan Harischandra
Lakshan Harischandra

Reputation: 10

The condition you have entered ,

while(opCode.equals("E")){

}

is not correct for this scenario. It will not be executed the block inside while loop, until you input E. So, Then none of your if else conditions satisfy.

Adding,

 while(!opCode.equals("E")){

}

for the code will help you. Thanks!

Upvotes: 0

thopaw
thopaw

Reputation: 4044

Perhaps because the while loop will terminate except for "E"?

while(opCode.equals("E")) {

only runs when it "E" but I think you mean

while(!opCode.equals("E")) {

Upvotes: 3

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