Java if Statement gives me a NullPointerException in an if statement

March 24, 2022

I’ve got the following if statement, where parent, grandparent, and child are all objects. For some reason, this if throws a NullPointerError when it comes to the parent.isRightChild() check. If this where an issue with the isRightChild() function, I would’ve caught it fairly easily, but it isn’t. This just baffles me, because there should be no way for parent to be null. Thanks in advance.

if (parent != null && grandparent != null
    && (parent.isLeftChild() && child.isRightChild())
    || (parent.isRightChild() && child.isLeftChild())
)

>Solution :

When parent and child objects are null and if condition is trying to access the parent.isRightChild() method. So it is throwing the NullPointerException.

if (parent != null && grandparent != null
    && (
          (parent.isLeftChild() && child.isRightChild())
         || (parent.isRightChild() && child.isLeftChild())
      )
)

group the method accessing conditions as separate(as shown above), so it will not reach those conditions if objects are null.