ndk hello world usage

If you want to make a ndk developing environment.

You can search for many useful sites in an internet.

I introduced my case. In fact, I have spent much time which was failed.

This is a rough scenario so, when you follow this scenario, you could miss detailed things. 

( So, I recommend using this guide only as a reference. )

1. First up, you should install cygwin.. When installing, you should check g++, gcc, swing, vim and make manually. 

(If you don't check them, when building it would be failed. )

2. Second up, you should install ndk.

3. Third up, in the activity which uses a native function, you should declare following.

static { 

 System.loadLibrary("csource"); 

 } 

 // declare the native code function - must match ndkfoo.c 

 private native String invokeNativeFunction();

4. make a natvie file as *.c

jstring Java_com_example_ndkexample_MainActivity_invokeNativeFunction(JNIEnv* env, jobject javaThis) {

 return (*env)->NewStringUTF(env, "Hello from C Code!");

}

The bold line means a package and the following word means the class which uses a native function. and the last word means the native function name. 

5. make an Android.mk

( refer to the other example in detail. )

LOCAL_PATH := $(call my-dir)

 

include $(CLEAR_VARS)

 

# Here we give our module name and source file(s)

LOCAL_MODULE := csource

LOCAL_SRC_FILES := csource.c

 

include $(BUILD_SHARED_LIBRARY)

6. execute the ndk-build which is placed in the ndk path. 

( At that time, you should be in the jni folder. )

If you success, the libs folder get to have a so file. 

Ok. I have attached the sample example zip. 

p.s) For detailing information, please refer to the following.

http://asurada0320.blogspot.de/2013/03/android-android-ndk.html

http://millo.tistory.com/2

http://gautambalasubramanian.blogspot.de/2012/08/hello-world-using-android-ndk.html

NDKExample.zip

NDKExample.zip

0.93MB