Android :: JNI Run Time Error Using Same Code And Lib

Now, I am trying to verify the JNI in Android Java platform. I am using HTC G1 phone. I write a simple .c file to make a hello.so and a simple hello.java file to load the library. My story is like below:

1. create hellolib.c file and compiled to a hellolib.so create a folder in create a hellolib.c file hellolib.c, it really nothing just a function return;
*#include <jni.h>*
*#define .LOG_TAG "TestLib"*
*#undef LOG*
*#include <utils/Log.h>*
*JNIEXPORT void JNICALL java_com_testHelloLib_PrintHello(JNIEnv
* env, jobject jobj)*
*{* *LOGD("hello android LIB");* *}*

I compiled the hellolib.c to .so by changing the android.mk:
*LOCAL_PATH:= $(call my-dir) include $(CLEAR_VARS)*
*LOCAL_SRC_FILES := hellolib.c*
*LOCAL_C_INCLUDES := $(JNI_H_INCLUDE)*
*LOCAL_SHARED_LIBRARIES := libutils
LOCAL_PRELINK_MODULE := false*
*LOCAL_MODULE := libhello *
*include $(BUILD_SHARED_LIBRARY)
* push the libhello.so to /system/lib

2. create a .java file.
*public class HelloAndroid extends Activity {
/** Called when the activity is first created. */
@Override public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
TextView tv = new TextView(this);
native_test.add_xx(1, 2) ;* * }* * }