Exception in thread "main"

Question

I don't know why I am incorrect in my bounds and why this error is thrown.

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException

private int gridSize = 3;
private Point currentStep = new Point(0, 0);
private Point firstStep = new Point(0, 0);
private Point lastStep = new Point(gridSize, gridSize);
private int pedometer = 0;
private int random;
private int down = 0;
private int right = 0;
private byte bottomReached = 0;
private byte rightReached = 0;
private int[][] clearPath2D;

public void createWalk2D() {

    clearPath2D = new int[gridSize][gridSize];
    for (currentStep = firstStep; currentStep != lastStep; pedometer++) {

        step2D();

        if (rightReached == 1 && bottomReached == 1) {
            break;
        }
    }

    clearField();
}

   public void step2D() {

    random = stepRand.nextInt();

    // add a new step to the current path
    currentStep.setLocation(right , down);
    clearPath2D[right][down] = 4;

    // calculates the next step based on random numbers and weather a side
    // is being touched

    if (currentStep.x == gridSize) {
        rightReached = 1;
        random = 1;
    }

    if (currentStep.y == gridSize) {
        bottomReached = 1;
        random = 0;
    }

    // decides the direction of the next step
    if (random >= 0.5 && bottomReached == 0) {
        down++;
    } else if (random < 0.5 && rightReached == 0) {
        right++;
    } else if (rightReached == 1 && bottomReached == 1) {
        done = true;
    }

}

so I call the createWalk2D(); then I get the error and eclipse points me to this line of code:

clearPath2D[right][down] = 4;

I assume this is because I am looping incorreclty. I have not been able to find a solution and have googled for about an hour three different days.

this isn't all the code but this is the part that I think is throwing it off. Thank you in advance for any help with the error. If you need the whole code please let me know.

EDIT: Nevermind I figured it out.

I had to add 1 to the initial declaration of the array

in this case it meant changing

clearPath2D = new int[gridSize][gridSize];

to

clearPath2D = new int[gridSize + 1][gridSize + 1];

Answer 1

Your immediate problem is in this section of code:

    if (currentStep.x == gridSize) {
        rightReached = 1;
        random = 1;
    }

    if (currentStep.y == gridSize) {
        bottomReached = 1;
        random = 0;
    }

You should be testing against gridSize-1, since that is the maximum valid index. As in:

    if (currentStep.x == gridSize-1) {
        rightReached = 1;
        random = 1;
    }

    if (currentStep.y == gridSize-1) {
        bottomReached = 1;
        random = 0;
    }