Question

I know that this code should work but it does not. Does anyone know what i am missing? I am trying to get the sum of all nodes in a binary tree.

public int getSum() {
    if (this == null) {
        return 0;
    } else {
        return this.value + right.getSum() + left.getSum();
    }
}

Answer 1

Your check this == null is completely useless. However, you do need to be checking for the existence of your left and right nodes. Try this:

return this.value + (right != null ? right.getSum() : 0)
        + (left != null ? left.getSum() : 0);