String checking for a while loop not working correctly

Question

Scanner scanner = new Scanner(system.in);
String input = new String();

while(!input.equalsIgnoreCase("stop")) {
input = scanner.nextLine();
}

Why is this not working? The loop lasts forever. I have used this method a million times before and now it wont work.

EDIT**

Okay I am using JGrasp (as this is what my professor wants us to use) and when I tried this in netbeans it worked fine...

EDIT2**

First of all I am not sure whether or not this is the problem but in my code I had something like this towards the beginning of main Scanner scanner = new Scanner(file); And later on something like this scanner = new Scanner(System.in); and that is where the previous code snippet starts off. So first of all I changed this by having main call a new method for the area where I needed the while loop with string checking. And I also reformatted the loop:

Scanner scanner = new Scanner(System.in);
    String input = new String();

    while(!input.contains("stop")) {
        System.out.print("Enter an option: ");
        input = scanner.nextLine();
    }

And now it works fine.

EDIT3**

So I tried the original format inside the new method and it also works perfectly. I believe now that it has something to do with how I had a scanner for the file and then reused that reference for a new scanner object with System.in. I am not 100% on that, but moving the while loop to a method of its own and not keeping it in main worked, so I feel like it has something to do with that.

The input line has to precisely equal "stop". It can't have an extra tab, space, non-printable unicode character, or anything else. — Robert Harvey
– Robert Harvey, Commented Oct 8, 2012 at 5:54

Kenneth K. · Accepted Answer · 2012-10-08 05:56:45Z

1

Perhaps you should be checking that the Scanner has something left to parse?

while(scanner.hasNextLine() && !input.equalsIgnoreCase("stop")) {
    input = scanner.nextLine();
}

answered Oct 8, 2012 at 5:56

Kenneth K.

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1 Comment

Ty_ Over a year ago

This is actually input by the user and not a file or anything, so the scanner would always have something left to parse...to the best of my knowledge.

Musa · Accepted Answer · 2012-10-08 06:21:11Z

0

Code is working fine: Except an compilation error i.e please use System.in instead of system.in

Scanner scanner = new Scanner(System.in);
String input = new String();

while(!input.equalsIgnoreCase("stop")) {
    input = scanner.nextLine();
}

edited Oct 8, 2012 at 6:21

Musa

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answered Oct 8, 2012 at 6:16

Tarun Gupta

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