Why is my count that is being returned a wrong value?

Question

    public static int countNeighbors(boolean[][] BB, int r, int c) {
    int countalive = 0;
    for (int i = r -1;i<=r+1; i++) {
        for (int j = c -1; j<c+1;j++) {

            if (BB[i][j]) {
                countalive++;

            }

        }
    }
    return countalive;
}

Matrix being read.

oooooooo
o###oooo
o####o#o
ooo##o#o
o#o#o##o
oooooooo

I noticed something wrong so I printed out this portion of the code. When ran with specifications

countNeighbors(myNewMatrix,1,1)

I get the returned value of 2, when it should in face be 3.

It is counting the number of tiles that are True(#) around it.

This is for a "game of life" assignment.

Answer 1

There are 3 neighbors of (1,1) at (1,2), (2,1), and (2,2). Your code is wrong on 2 accounts:

1. You are counting the cell itself (1,1). This makes the count 1 too high. Introduce an if to avoid counting the (r,c) location itself.
2. You are stopping too early in the j for loop, before it gets to c + 1. This makes the count 2 too low (missing 2 matches). Change the condition to j<=c+1, to be consistent with the i for loop condition.

The combined effects of the two errors (+1 and -2) explain why your count is low by 1.