Why does Java have a "NullPointerException" when there are no pointers in Java?

Question

Why do I get an exception called NullPointerException if in Java there is no such concept as a pointer?

Answer 1

There are no general purpose pointers in Java, that you can easily manipulate by adding and subtracting arbitrary values like in C. This can lead to all sorts of problems for those unused to them.

However, Java still needs to distinguish between an object and "no object". It's just the name of the exception that means you're trying to use an object reference that doesn't have a backing object behind it.

You could just as easily call it NoObjectException or DereferenceException, or one of a myriad of other names to minimise the possibility that people would think Java had general purpose pointers.

But NullPointerException is what the language creators opted for, probably because they were used to coding in C and/or C++.

Answer 2

Yes this is one of the first annoying things I learned when learning Java LOL. It really should be called NullReferenceException, NoObjectException or DereferenceException as paxdiablo mentioned. References don't even have to represented internally as pointers and you shouldn't have to care. "Most VMs including Sun's use handles, not pointers. A handle is a pointer to a pointer so who knows how they came up with using that?" Oh Microsoft's Java VM actually does use pointers rather than handles so go figure.