Execution failed for task ':app:dexDebug' android error
<p>I know this question has been asked previously but still I am not getting the answer for it. The code was working properly but when I tried to integrate it with firebase I started getting this error.</p>

<p>Error:Execution failed for task ':app:dexDebug'.</p>

<blockquote>
  <p>com.android.ide.common.process.ProcessException: org.gradle.process.internal.ExecException: Process 'command 'C:\Program Files\Java\jdk1.8.0_25\bin\java.exe'' finished with non-zero exit value 2</p>
</blockquote>

<p>I have tried building cleaning project but none of them are working. This is my gradle file</p>

<pre class="lang-groovy prettyprint-override"><code>apply plugin: 'com.android.application'

android {
    compileSdkVersion 23
    buildToolsVersion "23.0.2"

    defaultConfig {
        applicationId "in.protechlabz.www.sns"
        minSdkVersion 14
        targetSdkVersion 23
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }

    }

    dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')
    testCompile 'junit:junit:4.12'

    compile 'com.android.support:appcompat-v7:23.1.0'
    compile 'com.android.support:design:23.1.0'
    compile 'com.google.android.gms:play-services:8.3.0'
    compile 'com.google.android.gms:play-services-ads:8.3.0'
    compile 'com.google.android.gms:play-services-identity:8.3.0'
    compile 'com.google.android.gms:play-services-gcm:8.3.0'
    compile 'com.firebase:firebase-client-android:2.3.1'
}
</code></pre>