Java finished with non-zero exit value 2 - Android Gradle

I'm getting this error executing my Android app (I cleaned it and then built it, but the error is still present)

• Sync: OK
• Make Project: OK
• Clean: OK
• Run: Error

Error:Execution failed for task ':app:dexDebug' .com.android.ide.common.process.ProcessException: org.gradle.process.internal.ExecException: Process 'command 'C:\Program Files\Java\jdk1.7.0_25\bin\java.exe'' finished with non-zero exit value 2

My gradle file:

apply plugin: 'com.android.application'

android {
compileSdkVersion 21
buildToolsVersion "21.1.2"
defaultConfig {
    applicationId "com.rzr.rzevallosr.miappdepruebas"
    minSdkVersion 19
    targetSdkVersion 21
    versionCode 1
    versionName "1.0"
}
buildTypes {
    release {
        minifyEnabled false
        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
    }
}

productFlavors {
}

repositories {
    mavenCentral()
    flatDir {
        dirs 'libs'
    }
}
}

dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])

// This library handles authentication and authorization
compile 'com.spotify.sdk:spotify-auth:1.0.0-beta9@aar'
// This library handles music playback
compile 'com.spotify.sdk:spotify-player:1.0.0-beta9@aar'

compile 'com.android.support:appcompat-v7:21.0.3'
compile 'com.android.support:recyclerview-v7:21.0.+'

compile 'com.squareup.retrofit:retrofit:1.9.0'
compile 'com.squareup.okhttp:okhttp-urlconnection:2.2.0'
compile 'com.squareup.okhttp:okhttp:2.2.0'

compile files('libs/spotify-web-api-android-master-0.1.0.jar')
compile files('libs/okio-1.3.0.jar')
}

EDIT: I didn't see "compile fileTree(dir: 'libs', include: ['*.jar'])" it was compiling twice my libraries, so i just comment:

//compile 'com.squareup.retrofit:retrofit:1.9.0'
//compile 'com.squareup.okhttp:okhttp-urlconnection:2.2.0'
//compile 'com.squareup.okhttp:okhttp:2.2.0'

//compile files('libs/spotify-web-api-android-master-0.1.0.jar')
//compile files('libs/okio-1.3.0.jar')

and it works fine.

This issue is quite possibly due to exceeding the 65K methods dex limit imposed by Android. This problem can be solved either by cleaning the project, and removing some unused libraries and methods from dependencies in build.gradle, OR by adding multidex support.

So, If you have to keep libraries and methods, then you can enable multi dex support by declaring it in the gradle config.

defaultConfig {        
    // Enabling multidex support.
    multiDexEnabled true
}

You can read more about multidex support and developing apps with more than 65K methods here.

For me the problem was, i had put a unnecessary complie library code in build.gradle

dependencies {
    compile 'com.google.android.gms:play-services:7.5.0'
}

which was causing over 65k methods, so removed it,gradle sync, cleaned project, and then ran again and then this error stopped. I needed just maps and gcm so i put these lines and synced project

compile 'com.google.android.gms:play-services-gcm:7.5.0'
compile 'com.google.android.gms:play-services-location:7.5.0'

Hi people i again encountered this problem and this time it was because of changing build tools version and it really required me to enable multidex..so i added these my app's build.gradle file..

defaultConfig {
    applicationId "com.am.android"
    minSdkVersion 13
    targetSdkVersion 23
    // Enabling multidex support.
    multiDexEnabled true
}

dexOptions {
    incremental true
    javaMaxHeapSize "2048M"
    jumboMode = true
}

dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')
    compile 'com.android.support:multidex:1.0.1'
}

And create a class that extends Application class and include this method inside the class..

@Override
protected void attachBaseContext(Context base) {
    super.attachBaseContext(base);
    MultiDex.install(this);
}

also include in OnCreate method too

@Override
public void onCreate() {
    MultiDex.install(this);
    super.onCreate();
}

Just in case if someone still struggling with this and have no clue why is this happening and how to fix. In fact this error

Error:Execution failed for task ':app:dexDebug'. > com.android.ide.common.process.ProcessException: org.gradle.process.internal.ExecException: Process 'command 'C:\Program Files\Java\jdkx.x.x_xx\bin\java.exe'' finished with non-zero exit value 2

can have many reasons to happen but certainly not something related to your JDK version so don't wast your time in wrong direction. These are two main reasons for this to happen

1. You have same library or jar file included several places and some of them conflicting with each other.
2. You are about to or already exceeded 65k method limit

First case can be fixed as follows: Find out which dependencies you have included multiple times. In order to do this run following command in android studio terminal

gradlew -q dependencies yourProjectName_usually_app:dependencies --configuration compile

this will return all the dependencies but jar files that you include from lib folder try to get rid of duplication marked with asterisk (*), this is not always possible but in some cases you still can do it, after this try to exclude modules that are included many times, you can do it like this

compile ('com.facebook.android:facebook-android-sdk:4.0.1'){
    exclude module: 'support-v4'
}

For the second case when you exceeding method limit suggestion is to try to minimize it by removing included libraries (note sounds like first solution) if no way to do it add multiDexEnabled true to your defaultConfig

defaultConfig {
   ...
   ...
   multiDexEnabled true
}

this increases method limit but it is not the best thing to do because of possible performance issues IMPORTANT adding only multiDexEnabled true to defaultConfig is not enough in fact on all devices running android <5 Lollipop it will result in unexpected behavior and NoClassDefFoundError. how to solve it is described here

I didn't know (by then) that "compile fileTree(dir: 'libs', include: ['*.jar'])" compile all that has jar extension on libs folder, so i just comment (or delete) this lines:

//compile 'com.squareup.retrofit:retrofit:1.9.0'
//compile 'com.squareup.okhttp:okhttp-urlconnection:2.2.0'
//compile 'com.squareup.okhttp:okhttp:2.2.0'

//compile files('libs/spotify-web-api-android-master-0.1.0.jar')
//compile files('libs/okio-1.3.0.jar')

and it works fine. Thanks anyway! My bad.