null (Java)
In Java, Object variables are references (pointers) to memory the address where the object can be found. Therefore, the value null indicates that no address is available (no object reference is stored).
NullPointerException (Java)
A NullPointerException is thrown when code tries to use methods or fields inside of an object, but no object reference is available, (AKA the object reference is null).
Coding Chica 