While loop does not wait for if statement's completion

Question

I am working on a school project for Intro to CS and I can't post my code because our teacher fails us for getting code checked from StackOverflow. My issue is that in my code with the format :

while (condition){
Do something;

if (new condition){
Do something else;
Wait for input;
Depending on input make while's condition false;
}

This code should wait for input when the if statement is evaluated and it does something else. However, my code does not wait for "Wait for input" step and goes directly to the "Do something" step. Here's a bit of the code. Thank you for your help.

while (inum != 102) {
System.out.println("Enter a number between 1 and 100: ");
inum = input.nextInt();
else if (inum == 101) {
                System.out.println("Are you sure you want to quit?");
                confirm = input.nextLine();
                if (confirm == "yes") {
                    inum = 102;
                }
}

Here the code gives me this when I type in 101: Are you sure you want to quit? Enter a number between 1 and 100:

*The code does not wait for

confirm = input.nextLine();
                if (confirm == "yes") {
                    inum = 102;
                }

step.

@SotiriosDelimanolis and also else-if without any previous `if` shown in code — nachokk, Mar 06 '14 at 17:04
The most often asked question on SO, it seems... Replace `if (confirm == "yes")` with `if ("yes".equals(confirm))` — fge, Mar 06 '14 at 17:05
I still get the same response after changing to ("yes".equals(confirm)) — user3389265, Mar 06 '14 at 17:09
There's something funny about your braces and the placement of your else if. Can you check your example compiles and update as necessary? — Richard Miskin, Mar 06 '14 at 17:21

score 2 · Accepted Answer · answered Mar 06 '14 at 17:34

The easiest way to solve your problem is calling

input.nextLine();

just below

inum = input.nextInt();

The reason is: when you type "101" in the console, you really type 101 and NEWLINE. nextInt() takes the 101 from the console buffer, but the NEWLINE character remains. For that reason, the second nextLine() in your code was skipped (the code assumed you entered a new empty line)

score 1 · Answer 2 · answered Mar 06 '14 at 17:33

1

You should use confirm.equals("yes").
input is already use to input the number and declare another scanner object to input the confirm String.

answered Mar 06 '14 at 17:33

Myat Min Soe

787
8
32

score 0 · Answer 3 · answered Mar 06 '14 at 17:29

0

Define an other input Scanner and don't use the same for both String and int Try this code (I put System.exist(0) so the program exit when you enter yes)

import java.util.Scanner;

public class Test {

/**
 * @param args
 */
public static void main(String[] args) {
    int inum = 0;
    Scanner input = new Scanner(System.in);
    Scanner input1 = new Scanner(System.in);
    while (inum != 102) {
        System.out.println("Enter a number between 1 and 100: ");
        inum =  input.nextInt();
        if (inum == 101) {
            System.out.println("Are you sure you want to quit?");
            String confirm = input1.nextLine();
            if (confirm.equalsIgnoreCase("yes")) {
                inum = 102;
                System.exit(0);
            }
        }

    }
}

answered Mar 06 '14 at 17:29

JHDev

974
2
26
38

`confirm == "yes"` won't work. – Makoto Mar 06 '14 at 17:30
why -1 I just forget to put confirm.equalsIgnoreCase("yes") – JHDev Mar 06 '14 at 17:32
To remind you that your answer wasn't helpful. Seems like it worked. – Makoto Mar 06 '14 at 17:33
Do you need the System.exit(0)? won't the code now exit the while loop? If you don't care about the special inum ==102 case you could simply do `while (true)`. – Richard Miskin Mar 06 '14 at 17:34
It works but when I put the code like I said I forgot to change == with equals – JHDev Mar 06 '14 at 17:39
@Richard Miskin, I don't know why user3389265 puts this condition – JHDev Mar 06 '14 at 17:42
@esprittn I'm not sure either, but I'd suggest that you either use the `inum != 102` condition or use `System.exit(0)` (or maybe simply a `return;`). Your example is a little more complicated that necessary at the moment. – Richard Miskin Mar 06 '14 at 18:22

score 0 · Answer 4 · answered Mar 06 '14 at 17:33

0

if( StringUtils.equals(confirm, "yes") ) { ...

answered Mar 06 '14 at 17:33

deanosaur

621
3
5

While loop does not wait for if statement's completion

4 Answers4