What type of object is null Java?

No , null is not an object .It is a reference type and its value does not refer to any object and so there is no representation of null in memory.

In object-oriented computer programming, a null object is an object with no referenced value or with defined neutral (“null”) behavior . The null object design pattern describes the uses of such objects and their behavior (or lack thereof).

They are null by default for objects, 0 for numeric values and false for booleans. For variables declared in methods – Java requires them to be initialized. Not initializing them causes a compile time error when they are accessed.