How do I repeat a part of a code?

Question

I am trying to program a simple calculator program.But the problem is that when the user finishes his calculation, the program terminates. So I tried to make it in such a way that after you finish a calculation, the program asks you that if you want the program to terminate or not. But now I have no idea how to repeat the calculator program again infinitely.

My code (it is incomplete):

import java.util.Scanner ;
public class NewSrc
{
    public static void main(String[] args)
    {
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter first number.... ");
        double x = sc.nextDouble();
        System.out.println("Enter next number....");
        double y = sc.nextDouble();
        double z = x*y;
        System.out.println("processing answer ....");
        System.out.println("The answer is :- " + z );

        System.out.println("Do you want to continue ?Answer with either Yes or No ");
        String Agree = "Yes";
        String Disagree = "No";
        String Continue = sc.nextLine();
        if (Continue == Agree)
        {   
          //How to restart it?
        }
    }
 }

What about `loop` : https://docs.oracle.com/javase/tutorial/java/nutsandbolts/while.html ? — Shahid, Sep 26 '16 at 12:13
You need an infinite loop which will break when user says No. — Rishi Goel, Sep 26 '16 at 12:15
And please don't use capital CamelCase for variables names. **NEVER** http://www.oracle.com/technetwork/java/codeconventions-135099.html — Dorian, Sep 26 '16 at 12:23

Blobonat · Accepted Answer · 2016-09-26T12:39:07.240

1

Use a while loop

import java.util.Scanner ;
public class NewSrc {

 public static void main(String[] args) {

    boolean continueCalculation = true;
    Scanner sc = new Scanner(System.in);
    while (continueCalculation == true) {        
        System.out.println("Enter first number.... ");
        double x = sc.nextDouble();
        System.out.println("Enter next number....");
        double y = sc.nextDouble();
        double z = x*y;
        System.out.println("processing answer ....");
        System.out.println("The answer is :- " + z );
        System.out.println("Do you want to continue ?Answer with either Yes or No   ");
        String continueInput = sc.nextLine();
        if (continueInput.equals("No")) //do not use == to compare strings
        {
             continueCalculation = false;
        }
   }

 }

}

edited Sep 26 '16 at 12:39

answered Sep 26 '16 at 12:18

Blobonat

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Why shouldn't we use " == " to compare strings ? – TheEliteAlien Sep 26 '16 at 17:08
@TheEliteAlien Have a look at [this](http://stackoverflow.com/a/513839/5333936) answer. – Blobonat Sep 26 '16 at 17:39
Thanks for helping me out ! – TheEliteAlien Oct 02 '16 at 13:19

score 0 · Answer 2 · answered Sep 26 '16 at 12:17

A minor modification in your program to continue with loop based on user entered input otherwise discontinue

public static void main(String[] args) {

    while(true){
            Scanner sc = new Scanner(System.in);
            System.out.println("Enter first number.... ");
             double x = sc.nextDouble();
            System.out.println("Enter next number....");
             double y = sc.nextDouble();
             double z = x*y;
            System.out.println("processing answer ....");
             System.out.println("The answer is :- " + z );

            System.out.println("Do you want to continue ?Answer with either Yes or No   ");
                String Disagree = "No";
                String Continue = sc.nextLine();
                if (Continue.equals(Disagree ))
                {
                   break;
                }
    }

        }

Venkat · Answer 3 · 2016-09-26T12:45:51.533

import java.util.Scanner ;
public class NewSrc
{
    public static void main(String[] args)
    {
        boolean doRepeat = false;
        Scanner sc = new Scanner(System.in);

        do{

        System.out.println("Enter first number.... ");
        double x = sc.nextDouble();
        System.out.println("Enter next number....");
        double y = sc.nextDouble();
        System.out.println("processing answer ....");
        System.out.println("The answer is :- " + (x*y) );

        System.out.println("Do you want to continue ?Answer with either Yes or No ");
        String userWish= sc.nextLine();
        if (userWish.equalsIgnoreCase("Yes"))
        {   
          doRepeat = true;
        }
        else doRepeat = false;

       }(doRepeat)
    }
 }

Please do not use additional Variable declarations for just printing the output

use EqualsIgnoreCase method wherever applicable , it will enhance usability for end user to type as they wish

How do I repeat a part of a code?

3 Answers3