Can't get source code to build in JNI folder in Android Studio

Issue

I am using Android Studio 1.3 with the experimental NDK plugin enabled. I have dropped the entire Box2d folder into the jni folder in android studio along with Android.mk and Application.mk. Android studio seems to be completely ignoring the .mk files since when I change them nothing happens. Anyway I'm trying to compile Box2d when I get directoy not found errors. Error:(19, 42) Box2D/Collision/b2BroadPhase.h: No such file or directory.

Android.mk

LOCAL_PATH:= $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE:= liquidfun

LOCAL_C_INCLUDES := $(LOCAL_PATH)/Box2D/Collision \
            $(LOCAL_PATH)/Box2D/Collision/Shapes \
            $(LOCAL_PATH)/Box2D/Common \
            $(LOCAL_PATH)/Box2D/Dynamics \
            $(LOCAL_PATH)/Box2D/Dynamics/Contacts \
            $(LOCAL_PATH)/Box2D/Dynamics/Joints \
            $(LOCAL_PATH)/Box2D/Dynamics/Particle \
            $(LOCAL_PATH)/Box2D/Rope



include $(BUILD_SHARED_LIBRARY)

build.gradle

apply plugin: 'com.android.model.application'
model {
    android {
        compileSdkVersion = 21
        buildToolsVersion = "22.0.1"

        defaultConfig.with {
            applicationId = "com.mycompany.mygame"
            minSdkVersion.apiLevel = 15
            targetSdkVersion.apiLevel = 21
            versionCode = 1
            versionName = "1.0"
        }
    }
    android.buildTypes {
        release {
            minifyEnabled = false
            proguardFiles += file('proguard-rules.pro')
        }
    }
    android.ndk {
        moduleName = "liquidfun"
    }
}
def liquidFunDir = new File("${projectDir}/src/main/java/com/google/fpl/liquidfun")

task createLiquidFunDir {
    liquidFunDir.mkdirs()
}
dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'com.android.support:appcompat-v7:22.2.1'
}

Any tips would be much appreciated. Thanks.

Solution

Hey I had a similiar issue. The gradle plugin does not respect your Android.mk file. It creates a temp Android.mk for your project.

To add Cflags for in the new experimental android plugin:

apply plugin: 'com.android.model.application'
model {
    android {
        compileSdkVersion = 21
        buildToolsVersion = "22.0.1"

        defaultConfig.with {
            applicationId = "com.mycompany.mygame"
            minSdkVersion.apiLevel = 15
            targetSdkVersion.apiLevel = 21
            versionCode = 1
            versionName = "1.0"
        }
    }
    android.buildTypes {
        release {
            minifyEnabled = false
            proguardFiles += file('proguard-rules.pro')
        }
    }
    android.ndk {
        CFlags += "-I${projectDir}/src/main/jni/Box2D/Collision".toString()
        CFlags += "-I${projectDir}/src/main/jni/Box2D/Collision/Shapes".toString()
        CFlags += "-I${projectDir}/src/main/jni/Box2D/Dynamics".toString()
        CFlags += "-I${projectDir}/src/main/jni/Box2D/Dynamics/Contacts".toString()
        CFlags += "-I${projectDir}/src/main/jni/Box2D/Dynamics/Joints".toString()
        CFlags += "-I${projectDir}/src/main/jni/Box2D/Dynamics/Particle".toString()
        CFlags += "-I${projectDir}/src/main/jni/Box2D/Rope".toString()

        cppFlags += "-I${projectDir}/src/main/jni/Box2D/Collision".toString()
        cppFlags += "-I${projectDir}/src/main/jni/Box2D/Collision/Shapes".toString()
        cppFlags += "-I${projectDir}/src/main/jni/Box2D/Dynamics".toString()
        cppFlags += "-I${projectDir}/src/main/jni/Box2D/Dynamics/Contacts".toString()
        cppFlags += "-I${projectDir}/src/main/jni/Box2D/Dynamics/Joints".toString()
        cppFlags += "-I${projectDir}/src/main/jni/Box2D/Dynamics/Particle".toString()
        cppFlags += "-I${projectDir}/src/main/jni/Box2D/Rope".toString()
        moduleName = "liquidfun"
    }
}
def liquidFunDir = new File("${projectDir}/src/main/java/com/google/fpl/liquidfun")

task createLiquidFunDir {
    liquidFunDir.mkdirs()
}
dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'com.android.support:appcompat-v7:22.2.1'
}

Also it looks like you are compiling against sdk 10. @ph0b (https://stackoverflow.com/a/31365158/5105445) posted an answer that make it impossible to run on anything < lolipop.

Hope it helps

Answered By - canuc