10.3 Primitive types

Java provides 8 primitives types which represent integers, floats, characters and booleans (and also the void type). C++ has its own very similar concrete types. Such types in C++ however are not always implemented in the same way (an int might be 16, 32 or 64 bits for example) so CNI provides a special C++ type for each primitive Java type:

Java type	C/C++ typename	Description
char	jchar	16 bit Unicode character
boolean	jboolean	logical (true or false) values
byte	jbyte	8-bit signed integer
short	jshort	16 bit signed integer
int	jint	32 bit signed integer
long	jlong	64 bit signed integer
float	jfloat	32 bit IEEE floating point number
double	jdouble	64 bit IEEE floating point number
void	void	no value

When referring to a Java type You should always use these C++ typenames (e.g.: jint) to avoid disappointment.

10.3.1 Reference types associated with primitive types

In Java each primitive type has an associated reference type, e.g.: boolean has an associated java.lang.Boolean class. In order to make working with such classes easier GCJ provides the macro JvPrimClass: