title: build.gradle error set targetCompatibility t 1.7
body: <p>i got this error message saying<br>
  Error:Error converting bytecode to dex:Cause: Dex cannot parse version 52 byte code. This is caused by library dependencies that have been compiled using Java 8 or above. If you are using the 'java' gradle plugin in a library submodule add targetCompatibility = '1.7' sourceCompatibility = '1.7' to that submodule's build.gradle file.</p>
  
  <p>i tried to add targetCompatibility = '1.7'and sourceCompatibility = '1.7' inside the dependencies but it still gave me the same error,, how do i solve this?</p>
  
  <p>(i just added mysql connector to my library and it automatically generated that dependency)</p>
  
  <pre><code> apply plugin: 'com.android.application'
  
  android {
  compileSdkVersion 25
  buildToolsVersion "25.0.2"
  defaultConfig {
      applicationId "com.example.boneyflesh.connectnapls"
      minSdkVersion 17
      targetSdkVersion 25
      versionCode 1
      versionName "1.0"
      testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
  }
  buildTypes {
      release {
          minifyEnabled false
          proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
      }
  }
  }
  
  dependencies {
      compile fileTree(include: ['*.jar'], dir: 'libs')
      androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2',   {
      exclude group: 'com.android.support', module: 'support-annotations'
      })
      compile 'com.android.support:appcompat-v7:25.1.0'
      testCompile 'junit:junit:4.12'
      compile files('libs/mysql-connector-java-5.1.38-bin.jar')
  
     }
  </code></pre>