Getting Outputs As -1 On Every Inputs

#1

public int height() {
return this.height(root);
}
private int height(Node node) {
if(node==null) {
return -1;
}
int lheight=this.height(node.left);
int rheight=this.height(node.right);
int height=Math.max(lheight, rheight)+1;
return height;
}

#2

if node is null return 0