一起使用Java和C ++的Android项目

Question

Anybody have one example of a android project using a same time C++ and Java together, for example, one normal android project build on eclipse and in there add a cpp class and using this cpp class on java class...

say I have a class Foo on C++

class Foo{
...
}

and I have a class MyActivity on Java

public class MyActivity extends Activity{
...
}

how to i instance the Foo class on MyActivity class?...

thanks a lot for all.

Answer 1

First you have to make a .so of you c++ classes with build_ndk.sh

On the C++ side you have to declare your JNI methods

JNIEXPORT void JNICALL 
Java_org_your_ackage_someFunction(JNIEnv * env, jobject  obj)
{}

On the java side

public class YourActivity extends Activity {
    // Load Native Libary
    static {
        System.loadLibrary("your_lib_name");
    }

    public native void someFunction();
}

Then use the function as you would do in java.

You should take a look at this nice tutorial

Answer 2

If you're just trying to learn how to use the NDK, look at the documentation and samples in your NDK directory.

I would recommend starting with the hello-jni sample which is very easy to understand. It shows how to call C/C++ methods from Java.

Answer 3

You can find a lot of Android NDK examples under path/to/<android-ndk-folder>/samples . There is also a lot of helpful info in the docs folder, and on the official site .