The size of all other primitives in
Java are well-defined, but the size of boolean is not. I not aware of any JVM suppliers documenting how they handle booleans. I think it's safe to say that it's most likely between 1 and 32 bits in length, though that probably doesn't help you much. In fact it's probably between 1 and 8 bits: since all JVMs will support the "byte" data type, we know they can reference memory to that granularity.
The fact is, it's not defined. And there is no "sizeof" operator to fall back on ...