Android Studio NDK Build trouble Error:Execution failed for task ':app:buildNative'

Question

Hi. I'm in Android Studio NDK Build trouble. I've not used native library. just java classes for library use and JNI c or header files. So I've confused how to write gradle file for my project(saskin library ; I'm studying it). Please help me~!

Error message

Error:Execution failed for task ':app:buildNative'. A problem occurred starting process 'command 'C:\NDK/ndk-build''

build.gradle

apply plugin: 'com.android.application'
android {
    compileSdkVersion 8
    buildToolsVersion "21.1.1"

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.txt'
        }
    }

    sourceSets {
        main  {
            jni.srcDirs = []
            //jniLibs.srcDir 'src/main/libs'
        }
    }

    defaultConfig {
        applicationId "com.sasken.player"
        minSdkVersion 8
        targetSdkVersion 8

        ndk {
            moduleName "equalizer"
        }
    }

    // call regular ndk-build(.cmd) script from app directory
    task ndkBuild(type: Exec) {
        commandLine 'ndk-build', '-C', file('src/main/jni').absolutePath
    }

    tasks.withType(JavaCompile) {
        compileTask -> compileTask.dependsOn ndkBuild
    }
}

dependencies {
}

Solution

since you're using Windows, you should call ndk-build.cmd instead of ndk-build, from your ndkBuild task.

To make your gradle file work on windows and unix-compatible systems you can modify your task this way:

import org.apache.tools.ant.taskdefs.condition.Os

    // call regular ndk-build(.cmd) script from app directory
    task ndkBuild(type: Exec) {
        if (Os.isFamily(Os.FAMILY_WINDOWS)) {
            commandLine 'ndk-build.cmd', '-C', file('src/main').absolutePath
        } else {
            commandLine 'ndk-build', '-C', file('src/main').absolutePath
        }
    }

Also, as you're using ndk-build directly, the ndk will generate your libraries inside the libs folder, so you should uncomment jniLibs.srcDir 'src/main/libs' inside your gradle file, in order for your generated libs to be taken in account.