Finding valid neighbors in 2D array

Question

So, I have a 4x4 2D array (it will always be these dimensions). Starting with a location on the array, some row and column, I want to find all of its valid neighbors. So far, I

Answer 1

What constitutes a valid neighbor?

If all you want is to retrieve all the neighbors of a cell within the bounds of the array (including diagonals), this will suffice.

public List<Element> getNeighbors( int x, int y ) {
    List<Element> neighbors = new ArrayList<>();

    for( int i = -1; i <= 1; ++i ) {
        for( int j = -1; j <= 1; ++j ) {
            if( i == 0 && j == 0 ) {
                continue;
            }
            if( i + x >= 0 && i + x < array.length &&
                j + y >= 0 && j + y < array[0].length ) {
                    // we found a valid neighbor!
                    neighbors.add( array[i][j] );
            }
        }
    }

    return neighbors;
}