Game of life malfunctioning

Question

Why isn't my game of life working correctly? They don't always die when they're too crowded.

Relevant code is grann(x,y) which is supposed to return the number of living cells surrounding matrix[x][y], run is supposed to calculate the next generation:

private int grann(int x,int y) {
    int n = 0;
    for(int i=-1; i<2; i++) {
        for(int j=-1; j<2; j++) {
            if(i!=0 || j!=0) {
                if(matrix[x+i][y+j]) {
                    n++;
                }
            }
        }
    }
    return n;
}
public void run() {
    boolean[][] next = matrix;
    for(int i=1; i<w; i++) {
        for(int j=1; j<h; j++) {
            int n = grann(i,j);
            if(matrix[i][j]) {
                if(!(n==2 || n==3)) {
                    next[i][j] = false;
                }
            } else {
                if(n==3) {
                    next[i][j] = true;
                }
            }
        }
    }
    matrix = next;
}

The object has a matrix, width and height. matrix is a boolean[w+2][h+2], and w and h are ints.

If you don't know the rules of Conway's game of life: http://en.wikipedia.org/wiki/Conway%27s_Game_of_Life

Because `next = matrix` does not *copy* the matrix. They both point to the same object. So the changes you make affect the calculation for the surrounding cells. — RealSkeptic, Mar 13 '15 at 11:19
possible duplicate of [Game of Life, method doesnt work](http://stackoverflow.com/questions/25832120/game-of-life-method-doesnt-work) — RealSkeptic, Mar 13 '15 at 11:22
See [this answer](http://stackoverflow.com/a/1564856/4125191) for copying 2d arrays. — RealSkeptic, Mar 13 '15 at 11:29

score 0 · Answer 1 · answered Apr 10 '16 at 09:09

0

I think the problem is that grann should say:

if(i != 0 && j != 0)

because you want to eliminate just the centre square of the 3x3 area you are checking (the cell itself), not the row and column it is in also.

answered Apr 10 '16 at 09:09

dangee1705

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Game of life malfunctioning

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