System.exit(0) not working

Question

I have been coding Java for a short period of time so I do not know why my System.exit(0) command is not working.

This program tests a user on 1st or 2nd grade math. It takes in two "random" numbers and the user answers arithmetic questions. When the program asks the user whether they want to play again, entering N for No does not seem to register with the if statement that contains System.exit(0). The program just restarts as if the user entered Y.

import java.util.*;


    class Tester {
        public static void main (String[] args) {

            SuperRandom randomNumberGenerator = new SuperRandom();

            Scanner scan = new Scanner (System.in);

            int selection, q1_1, q1_2, q1_3, q1_4, q1_5, questans;

            int score = 0;

            int a;

            int b, i;

            String scanchoice;

            String choice = "Y";

            final int numberOfQuestions = 5;

            int getNextRandom;

            int answer;

            while (choice == "Y"){

                System.out.println ("Welcome to Math Tester 2.0.");

                System.out.println ("");

                System.out.println ("Please enter your grade level:");

                System.out.println ("1. 1st Grade Test");

                System.out.println ("2. 2nd Grade Test");

                System.out.println ("3. Quit Math Tester 2.0");

                    selection = scan.nextInt();

                        if (selection == 1) {

                                System.out.println ("Enter: " +selection);

                                System.out.println ("");

                                for (i=1; i<=5; i++){

                                    a = randomNumberGenerator.getNextRandom(numberOfQuestions);

                                    b = randomNumberGenerator.getNextRandom(numberOfQuestions);

                                    System.out.println ("What is " +a + " + " +b + "?");

                                    answer = a+b;

                                    questans = scan.nextInt();

                                    System.out.println("" +questans);

                                        if (questans == answer){

                                            score++;        
                                        }

                                }   

                                System.out.println ("");

                                System.out.println ("Max points possible: 5.");

                                System.out.println ("Your score: " +score);

                                System.out.println ("Do you wish to play again (Enter Y for Yes or N for No)?");

                                    choice = scan.next();

                                        if (choice = "N") {

                                            System.out.println ("Goodbye!");

                                            System.exit(0); //Exits program if user entered N.
                                        }
                                        if (choice = "Y");

                                            choice = "Y";
                                        }   


                    if (selection == 2){

                        System.out.println ("Enter: " +selection);

                        System.out.println ("");    

                    }

                    if (selection == 3){

                        System.out.println ("Goodbye!");

                        System.exit(0);
                    }


            }

        }

    }

Prateek it does not print Goodbye – user2873202 Oct 12 '13 at 04:52 — user2873202, Oct 12 '13 at 04:52
There is your answer. Selection never equates to 3 – Prateek Oct 12 '13 at 04:52 — Prateek, Oct 12 '13 at 04:52

score 0 · Answer 1 · answered Oct 12 '13 at 04:51

0

System.exit() is not executed in your code because your if/else conditions are not right. Use equals for string comparion instead of ==.

answered Oct 12 '13 at 04:51

Juned Ahsan

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1

Seriously? Posting an answer instead of voting as duplicate? – Luiggi Mendoza Oct 12 '13 at 04:52
1

@LuiggiMendoza I am posting this becuase he is claiming that System.exit is not working. To make him understand that the line is never executed. – Juned Ahsan Oct 12 '13 at 04:52
1

The problem is very clear: String comparison is wrong. After fixing that, it should work =\ – Luiggi Mendoza Oct 12 '13 at 04:53
now i get the error, "cannot convert string to boolean" once i fixed the comparison for the if statement. – user2873202 Oct 12 '13 at 04:56
1

@user2873202 share your latest code. – Juned Ahsan Oct 12 '13 at 04:56
@user2873202 Update your questions with the latest code. – Juned Ahsan Oct 12 '13 at 04:58
the code has been updated – user2873202 Oct 12 '13 at 04:58
my while still needs to be fixed i see that, but my main concern is the if statements – user2873202 Oct 12 '13 at 05:00
but I do get the same error if I change it to while (choice = "Y") – user2873202 Oct 12 '13 at 05:01
you will have to use equals with choice also – Rat-a-tat-a-tat Ratatouille Oct 12 '13 at 05:02
you need replace `choice = "Y"` by `choice.equals("Y")` :D – Tuna Oct 12 '13 at 05:03
@user2873202 check my edited answer. You are suing single = for comparision, which is wrong. – Juned Ahsan Oct 12 '13 at 05:06
@user2873202 Enjoying coding =)) – Tuna Oct 12 '13 at 05:09
@TuanDang that's covered in the possible duplicate question =\ – Luiggi Mendoza Oct 12 '13 at 05:11

score 0 · Answer 2 · answered Oct 12 '13 at 05:04

As per the comments in Juned Ahsan'anwer you should change = to == or .equals() for example in this line if (choice = "N") { it should be if (choice.equals("N")) { Though == will not work in your case you should use .equals() = is an assignment operator where as == is a relational operator

System.exit(0) not working

2 Answers2