无法生成签名的APK

Question

I have to create an Application using android studio and need to generate signed Apk but when i generate signed Apk it will show some warning and build failed please help me to solve this problem here is my error log file

Information:Gradle tasks [:app:assembleRelease]
Information:0 errors
Information:0 warnings
Information:See complete output in console
Warning:com.kosalgeek.android.photoutil.MainActivity: can't find        referenced class com.kosalgeek.android.photoutil.R$layout
Warning:com.kosalgeek.android.photoutil.MainActivity: can't find    referenced class com.kosalgeek.android.photoutil.R$id
Warning:com.kosalgeek.android.photoutil.MainActivity: can't find    referenced class com.kosalgeek.android.photoutil.R$menu
Warning:com.kosalgeek.android.photoutil.MainActivity: can't find    referenced class com.kosalgeek.android.photoutil.R$id
Warning:com.kosalgeek.android.photoutil.MainActivity: can't find referenced  class com.kosalgeek.android.photoutil.R$layout
Warning:com.kosalgeek.android.photoutil.MainActivity: can't find referenced class com.kosalgeek.android.photoutil.R$id
Warning:com.kosalgeek.android.photoutil.MainActivity: can't find referenced class com.kosalgeek.android.photoutil.R$menu
Warning:com.kosalgeek.android.photoutil.MainActivity: can't find referenced class com.kosalgeek.android.photoutil.R
Warning:there were 9 unresolved references to classes or interfaces.
Warning:Exception while processing task java.io.IOException: Please      correct the above warnings first.
Error:Execution failed for  task    ':app:transformClassesAndResourcesWithProguardForRelease'.
> java.io.IOException: Please correct the above warnings first.
Information:BUILD FAILED
Information:Total time: 1 mins 31.858 secs

I have photoutil.jar file in my libs folder but again a get the same error please help me to solve the problem thanks in advance here is my gradle

apply plugin: 'com.android.application'

 android {
compileSdkVersion 24
buildToolsVersion "24.0.3"
defaultConfig {
    applicationId "com.example.jijoabraham.informe"
    minSdkVersion 15
    targetSdkVersion 24
    versionCode 1
    versionName "1.0"
    testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    multiDexEnabled true
}
buildTypes {
    release {
        minifyEnabled true
        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
    }
}
repositories {
    maven {
        url "http://dl.bintray.com/lukaville/maven"

    }
    maven { url "https://jitpack.io" }
    }
   }
     configurations{
     all*.exclude group: 'com.mcxiaoke.volley'
  }
  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 files('libs/PhotoUtil.jar')
     compile 'com.android.support:multidex:1.0.1'
    compile 'com.android.support:cardview-v7:24.2.1'
      compile 'com.android.support:recyclerview-v7:24.2.1'
    compile 'com.android.support:palette-v7:24.2.1'
    compile 'com.android.support:support-v4:24.2.1'
   compile 'com.mcxiaoke.volley:library-aar:1.0.0'
compile 'com.android.support:appcompat-v7:24.2.1'
compile 'com.android.support:design:24.2.1'
compile 'com.oguzdev:CircularFloatingActionMenu:1.0.2'
compile 'com.yqritc:recyclerview-flexibledivider:1.2.4'
compile 'com.squareup.okhttp3:okhttp:3.3.1'
compile 'com.nbsp:library:1.09'
compile 'com.github.PhilJay:MPAndroidChart:v2.0.9'
compile 'com.google.firebase:firebase-database:9.6.1'
compile 'com.google.firebase:firebase-core:9.6.1'
compile 'com.pkmmte.view:circularimageview:1.1'
testCompile 'junit:junit:4.12'
 }


  apply plugin: 'com.google.gms.google-services'

please help me to solve this problem thanks in advance

Answer 1

In your gradle add this.

android {
        packagingOptions {
            exclude 'META-INF/DEPENDENCIES.txt'
            exclude 'META-INF/LICENSE.txt'
            exclude 'META-INF/maven/pom.properties'
            exclude 'META-INF/NOTICE.txt'
            exclude 'META-INF/NOTICE'
            exclude 'META-INF/LICENSE'
            exclude 'META-INF/DEPENDENCIES'
            exclude 'META-INF/notice.txt'
            exclude 'META-INF/license.txt'
            exclude 'META-INF/dependencies.txt'
            exclude 'META-INF/LGPL2.1'

        }
    }

In proguard-rules.pro add

-dontwarn com.kosalgeek.android.photoutil.**

And set true to minifyEnabled true May be this will help.

Answer 2

As I can see you have enabled proguard in your release build so it is very common getting warnings with pruguard.

In your case those are related to the lib com.kosalgeek.android.photoutil. I think you should use -dontwarn as Devendra suggested above.

If this doesn't work then probably you should find the correct proguard rules for your library.