应用程序成功构建没有错误，但运行时出现错误

Question

所以我的项目成功构建但是当我尝试在我的设备上运行应用程序时，我收到此错误。我完全不知道为什么。每次尝试运行它都会花费20多分钟。

Error:Execution failed for task ':app:transformClassesWithDexForDebug'.
> com.android.ide.common.process.ProcessException: org.gradle.process.internal.ExecException: Process 'command 'C:\Program Files\Java\jdk1.8.0_65\bin\java.exe'' finished with non-zero exit value 3

这是我的项目构建文件;

//顶级构建文件，您可以在其中添加所有子项目/模块共有的配置选项。

    buildscript {
        repositories {
            jcenter()
        }
        dependencies {
            classpath 'com.android.tools.build:gradle:1.5.0'
            classpath 'com.google.gms:google-services:2.0.0-alpha6'

            // NOTE: Do not place your application dependencies here; they belong
            // in the individual module build.gradle files
        }
    }

    allprojects {
        repositories {
            jcenter()
        }
    }

    task clean(type: Delete) {
        delete rootProject.buildDir
    }
 and here is my app build file 

apply plugin: 'com.android.application'

android {
    compileSdkVersion 23
    buildToolsVersion "23.0.2"

    defaultConfig {
        applicationId "com.fyp.android.housesplittr"
        minSdkVersion 15
        targetSdkVersion 23
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}
apply plugin: 'com.google.gms.google-services'
dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')
    testCompile 'junit:junit:4.12'
    compile 'com.android.support:appcompat-v7:23.1.1'
    compile 'com.android.support:design:23.1.1'
    compile project(path: ':Backend', configuration: 'android-endpoints')
    compile 'com.google.android.gms:play-services-auth:8.3.0'
    compile project(':Backend')
}

非常感谢任何帮助。