Is null an Object?

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If null were an Object, it would support the methods of java.lang.Object such as equals(). However, this is not the case – any method invocation on a null results in a NullPointerException.

And this is what the Java Language Specification has to say on this topic:

There is also a special null type, the
type of the expression null, which has
no name. Because the null type has no
name, it is impossible to declare a
variable of the null type or to cast
to the null type. The null reference
is the only possible value of an
expression of null type. The null
reference can always be cast to any
reference type. In practice, the
programmer can ignore the null type
and just pretend that null is merely a
special literal that can be of any
reference type.

I think this can be boiled down to “null is special”.

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