On 17 Nov 2006 04:46:11 -0800, =?gb2312?B?yMrV387etdA=?= wrote:

Static methods have "jclass" instead.

It makes calls to GetFieldID() to look up commonly used fields in the
class. This is a relatively expensive operation that only needs to be
done once for a given class. By caching the results the ids can be
reused by subsequent calls to the class's other native methods.

See section 10.7:
http://java.sun.com/docs/books/jni/html/pitfalls.html#29161

Why don't you get the source and check for yourself?

/gordon

仁者无敌 schrieb:

You don't need it for getting method or field IDs.

It might do for example look below:

#include "FileInputStream.h"

static jmethodID readMethodID;
static jmethodID closeMethodID;

void Java_FileInputStream_initIDs(JNIEnv *env, jclass c)
{
 readMethodID = env->GetMethodID(env, c, "read", "()I");
 closeMethodID = env->GetMethodID(env, c, "close", "()V");
}

void Java_FileInputStream_exampleMethod(JNIEnv *env, jobject obj)
{
 env->CallVoidMethod(env, obj, closeMethodID);
}

By the way: If you want a deeper understanding of JNI, I suggest you
work through Sun's JNI tutorial and/or a text-book.