Question

In JNI there are jtypes. Like jint for int and jboolean for boolean. I understand the latter types are c/c++ types . But type is a jtype ? In books they mention this type also a native type. What is meant by that ?

EDIT:

What is the use of jtype ?

Answer 1

From jni.h,

typedef unsigned char   jboolean
typedef unsigned short  jchar
typedef short   jshort
typedef float   jfloat
typedef double  jdouble
typedef long    jint
typedef jint    jsize

By native types they don’t mean native to Java language, they mean native C or native machine equivalents. The j versions, aid to map Java types to native C types. The advantage of this mapping is, a Java programmer familiar with basic Java types can continue using the same names with the just the added j. He need not bother how are they mapped into the machine’s basic type. It will be taken care by the typedefs. Also if the underlying machine architecture changes, still you need not bother, just chaging the typedefs will do

Addressing your concerns in comments, _jstring is a class. And jstring is a pointer to this class

class _jstring : public _jobject {};
typedef _jstring *jstring;

Just like we have the String class in C++