ArrayList not adding objects?

Question

I have a piece of code:

public void setBoardMemberPosition() {

    int[] position = null;

    do{
        positionX = RandomNumberGenerator.generateRandomNumber(Board.DIMENSION);
        positionY = RandomNumberGenerator.generateRandomNumber(Board.DIMENSION);

        position = new int[] { positionX, positionY };


    } while(checkIfPositionIsOccupied(position));

    board.setElementAt(positionX, positionY, name);
    storedMembers.add(position);

}

Can someone explain to me why the elements are not being added to the list, where:

private ArrayList<int[]> storedMembers = new ArrayList<int[]>();is a Class variable and:checkIfPositionIsOccupied(position) returns true/false

if (storedMembers.contains(position))

i have a feeling its something to do with the do while, ive debugged it with no luck.

Christian Tapia · Accepted Answer · 2014-03-21 18:19:44Z

2

If you want to add the array position to the ArrayList on each iteration, your add() call must be inside the loop:

do {
    // ...

    storedMembers.add(position);
} while(...);

Edit:

for (int i = 0; i < storedMembers.size(); i ++)
    // ...

    if (!checkIfPositionIsOccupied(position))
        storedMembers.add(position);
}

edited Mar 21, 2014 at 18:19

answered Mar 21, 2014 at 18:09

Christian Tapia

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6 Comments

smurfMT Over a year ago

But i dont need it to be on each itteration, just if checkIfPositionIsOccupied(position) returns false. thats why i initalised the variable before the loop??

Christian Tapia Over a year ago

Then you can add a condition inside the loop. The check checkIfPositionIsOccupied(position) shouldn't be loop condition. But you will have to think how many iterations there would be?

smurfMT Over a year ago

so i should probably use a for loop of storedMembers.size() itterations?

Christian Tapia Over a year ago

Yes, in that case a for loop will be better. See edit.

smurfMT Over a year ago

Ok ill try it that way, but it still dosent clear up the original problem... im not understanding it atall, ive even tried adding it to the list int the checkIfPositionIsOccupied(position) method with no luck...

|

Zarathustra · Accepted Answer · 2014-03-21 18:08:15Z

0

Because you don't add in your while loop anything to the list?!

answered Mar 21, 2014 at 18:08

Zarathustra

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