why java.exe exit with value 1 in android studio

Question

Error:Execution failed for task \':app:dexDebug\'.

com.android.ide.common.process.ProcessException: org.gradle.process.internal.ExecException: Process

Answer 1

build.gradle:

apply plugin: 'com.android.application'

android {
    compileSdkVersion 21
    buildToolsVersion "21.1.2"

    defaultConfig {
        //multiDexEnabled false

        applicationId "com.example.aishwarya.myapplication"
        minSdkVersion 16
        targetSdkVersion 21
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')
    compile 'com.android.support:appcompat-v7:21.0.3'
    //compile files('libs/android-support-v4.jar')
    compile files('libs/gson-2.2.4.jar')
    compile files('libs/okhttp-1.6.0.jar')
    compile files('libs/okhttp-urlconnection-1.6.0.jar')
    compile files('libs/okio-1.0.0.jar')
    compile files('libs/otto-1.3.4.jar')
    compile files('libs/picasso-2.3.1.jar')
    compile files('libs/retrofit-1.5.1.jar')
    compile files('libs/scribe-1.3.5.jar')
    compile files('libs/twitter-text-1.6.1.jar')
    compile 'com.android.support:support-v4:21.0.3'
}