The Java boolean type maps to the Win32 BOOL type, which is a 32-bit type. As a parameter, the Java true maps to 1, and false maps to 0 (zero). As a return value, all non-zero values map to true.
Note BOOL and VARIANT_BOOL (the internal boolean type in Microsoft® Visual Basic®) are not interchangeable. To pass a VARIANT_BOOL to a Visual Basic DLL, you must use the Java short type and use -1 for VARIANT_TRUE, and 0 for VARIANT_FALSE.