[Cocos3.0 Tutorial] Call Java functions on Cocos2d-x

[javi_moralesf]

[Cocos3.0 Tutorial] Call Java functions on Cocos2d-x v3.0 Final

Get files

1. Download http://cdn.cocos2d-x.org/cocos2d-x-3.0.zip
2. Unzip it
3. copy cocos2d-x3.0 to your workspace

Create project

Prepare environment

1. Open a terminal on cocos2d-x folder
2. Run “Python setup.py” to make sure all environment variables are properly defined
   
   
3. Now we will create our project with command “cocos new ProjectName -p project.package -l language -p PROJECT_DIRECTORY”
   cocos new JniTest -p com.test.jnitest -l cpp -d /Users/javi_moralesf/Documents/workspace/tutorials/
   
   

Import projects on Eclipse

Import “inappTest\proj.android” :

1. Open eclipse
2. Eclipse → Create a new Workplace
3. File → New → Project → Android → Android Project from Exiting Code → Next
   
   
   
   
   
4. Root Directory → Browse “PROJECT_LOCATION\JniTest\proj.android” → Finish
   
   
5. Project → Properties → Android → Project build target :
6. This tutorial was made on 4.0 (API 14)
7. Apply → Ok.
   
   

Import “libcocos2dx” :

1. Go to eclipse

2. File → Import → Android → Exiting Android code into Workplace → Next
   

   
   
   
   

3. Root Directory → Browse “PROJECT_LOCATION\JniTest\cocos2d\cocos” → Finish
   

   

Build project

Compile c++ files

1. Open terminal on “PROJECT_LOCATION\JniTest\proj.android”
2. Run “Python build_native.py”.
   
   
   
   
   
   
   
   
3. If you have some error, check your environment variables again.

Build java project

1. Go to eclipse
2. Connect an Android device (adb enabled).
   Run → Run → Android Application → Choose a running Android Device → OK
   Auto Monitor logcat → yes, Monitor logcat and display … → Ok (will use this later for device hash)
   
   
   
   
   
   
   Make sure “Hello World” showing and working correctly.

Edit code

Java

Now we will add a function on AppActivity to be called from C++ code.

public static Activity _activiy;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
	    super.onCreate(savedInstanceState);

	    //Save activity instance
	    _activiy = this;
    }

    public static void alertJNI() {
	    String tag = "JniTest";
	    String message = "I've been called from C++";
        Log.d(tag, "Showing alert dialog: " + message);
    }

C++

1. First we need to include JniHelper and jni headers

   #include "platform/android/jni/JniHelper.h"
#include <jni.h>

2. And finally we will call our java function from C++ code

    void HelloWorld::menuCloseCallback(Ref* pSender)
    {
        cocos2d::JniMethodInfo methodInfo;
    
        if (! cocos2d::JniHelper::getStaticMethodInfo(methodInfo, "org/cocos2dx/cpp/AppActivity", "alertJNI", "()V")) {
            return;
        }
    
        methodInfo.env->CallStaticVoidMethod(methodInfo.classID, methodInfo.methodID);
        methodInfo.env->DeleteLocalRef(methodInfo.classID);
    }
   

Then we do again “Python build_native.py” and build android application:

Now when we press the off button, the java function alertJNI is called:

[owen]

@javi_moralesf

thanks, great job:)

[Suigintou]

The pictures somehow do not show up. I can’t see the detail. Would you mind check this problem…

[duckinferno]

Thanks a ton, this is really helpful

[zijian_rao]

@javi_moralesf

Can you update your pictures url? I cannot see them