More efficient way to check neighbours in a two-dimensional array in Java

Question

Hey all, for a few of my college assignments I\'ve found the need to check neighbouring cells in 2-dimensional arrays (grids). The solution I\'ve used is a bit of a hack usi

Answer 1

You can try this. First decide the size of the grid Lets say its 8 X 8 & assign MIN_X = 0, MIN_Y = 0, MAX_X =7, MAX_Y =7

Your curren position is represented by thisPosX , thisPosY, then try this:

int startPosX = (thisPosX - 1 < MIN_X) ? thisPosX : thisPosX-1;
int startPosY = (thisPosY - 1 < MIN_Y) ? thisPosY : thisPosY-1;
int endPosX =   (thisPosX + 1 > MAX_X) ? thisPosX : thisPosX+1;
int endPosY =   (thisPosY + 1 > MAX_Y) ? thisPosY : thisPosY+1;


// See how many are alive
for (int rowNum=startPosX; rowNum<=endPosX; rowNum++) {
    for (int colNum=startPosY; colNum<=endPosY; colNum++) {
        // All the neighbors will be grid[rowNum][colNum]
    }
}

you can finish it in 2 loops.