The3 Java Language Spec documents all this stuff definitively. For throw it says
14.18 The throw Statement
A throw statement causes an exception (§11) to be thrown
... ThrowStatement: throw Expression ;
The Expression in a throw statement must denote either 1) a variable or value of
a reference type which is assignable (§5.2) to the type Throwable, ...
(plus a load of stuff about what happens if ot goes wrong)
So there's really not a lot to say in answer to your question. The only way to write it is "throw" followed by something that is or extends Throwable (eg an Exception).