Java Endless While Loop

Question

I have the following code:

boolean[] usedInts = {false, false, false, false, false, false, false, false, false};
for(int i = 0; i <= 8; i++) {
    JLabel square = squares[i];

    // Declare coordinate
    Coordinate coordinate = null;

    boolean keepGoing = true;
    while (keepGoing) {
        // Get random number
        int rand = generateRandom();

        if (usedInts[rand]) {
            keepGoing = true;
        } else {
            // Save that we used it
            usedInts[rand] = true;
            keepGoing = false;
        }
        // Initialize coordinate
        coordinate = coordinates[rand];
    }

    // Set square coordinates
    square.setLocation(coordinate.getX(), coordinate.getY());
    // Set used to true
}

The problem is that the while loop is endless and the else part only runs 8 times. What is going on here?

You need to give us some more code. Currently we don't know what `coordinates` is, what `square` is. As it stands, the question is quite vague to be answerable. — Rohit Jain, Jul 01 '13 at 19:36
If you are trying to generate random permutation of coordinates then you might find that Collections.shuffle method is more convenient way to do this (unless you have very special requirements for random generator). — Darth Beleg, Jul 01 '13 at 19:44

score 3 · Accepted Answer · answered Jul 01 '13 at 19:37

3

The only possibility I see is that your generateRandom method generates numbers in range 0..7 (only 8 numbers, not 9) or 1..8 for example

answered Jul 01 '13 at 19:37

Tala

8,888
5
34
38

You and me Tala, we've got this haha – William Morrison Jul 01 '13 at 19:40
1

Yep. StackOverflow saved years in total for developers :)))) – Tala Jul 01 '13 at 19:43

score 2 · Answer 2 · answered Jul 01 '13 at 19:37

2

I'm guessing its because your generateRandom function isn't returning a correct range.

answered Jul 01 '13 at 19:37

William Morrison

10,953
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score 0 · Answer 3 · answered Jul 01 '13 at 22:21

0

Add the generateRandom method so we can fix your problem.

answered Jul 01 '13 at 22:21

La2o

1
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Java Endless While Loop

3 Answers3