solve error: cannot access Publisher in Android Studio?

Question

I am getting this error while compilation of my code:

Can anyone help me how to solve this error or what might be causing this error?

Edit1: Gradle

Answer 1

in my case the Publisher class was belong to the RxJava library which was missing from my project so adding these two lines in my app/gradle file fixed the problem:

implementation 'io.reactivex.rxjava2:rxandroid:2.1.1'

implementation 'io.reactivex.rxjava2:rxjava:2.x.x'

Answer 2

Make sure in your project gradle buildscript you use latest version:

classpath 'com.android.tools.build:gradle:3.3.2'
classpath 'com.google.gms:google-services:4.2.0'

And also try to update version of your libraries use latest version:

dependencies {
    implementation fileTree(include: ['*.jar'], dir: 'libs')

    implementation 'com.adcolony:sdk:3.3.0'
    implementation 'com.google.ads.mediation:adcolony:3.2.1.1'
    implementation 'com.google.android.material:material:1.0.0'
    implementation "com.google.firebase:firebase-measurement-connector-impl:17.0.5"

//noinspection GradleCompatible
    implementation 'com.google.ads.mediation:facebook:4.27.0.0'
    implementation 'com.facebook.android:audience-network-sdk:4.27.0'
    implementation 'com.loopj.android:android-async-http:1.4.9'
    implementation 'com.danikula:videocache:2.7.0'

//noinspection GradleCompatible
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support:design:28.0.0'
    implementation 'com.google.code.gson:gson:2.8.5'
    implementation 'com.squareup.retrofit2:retrofit:2.5.0'
    implementation 'com.squareup.retrofit2:converter-gson:2.5.0'
    implementation 'io.reactivex.rxjava2:rxandroid:2.0.2'
    implementation 'io.reactivex.rxjava2:rxjava:2.1.16'
    implementation 'com.squareup.retrofit2:adapter-rxjava2:2.4.0'
    implementation 'com.squareup.picasso:picasso:2.71828'
    implementation 'com.android.support:recyclerview-v7:28.0.0'
    implementation 'com.android.support:cardview-v7:28.0.0'


//noinspection GradleCompatible
    implementation 'com.google.firebase:firebase-core:16.0.8'
    implementation 'com.google.firebase:firebase-messaging:17.4.0'
    implementation 'com.google.firebase:firebase-crash:16.2.1'
    implementation 'com.google.firebase:firebase-auth:16.2.0'
    implementation 'com.firebaseui:firebase-ui-database:4.3.1'
    implementation 'com.firebaseui:firebase-ui-auth:4.3.1'

    implementation 'org.piwik.sdk:piwik-sdk:2.0.0'
    implementation 'com.android.support:multidex:1.0.3'
    debugImplementation 'com.amitshekhar.android:debug-db:1.0.0'

// Room components
    implementation 'android.arch.persistence.room:runtime:1.1.1'
    annotationProcessor "android.arch.persistence.room:compiler:1.1.1"
    androidTestImplementation 'android.arch.persistence.room:compiler:1.1.1'
// Lifecycle components
    implementation 'android.arch.lifecycle:extensions:1.1.1'
    annotationProcessor "android.arch.lifecycle:compiler:1.1.1"
    implementation 'com.crashlytics.sdk.android:crashlytics:2.9.9'
    implementation 'junit:junit:4.12'
    testImplementation 'junit:junit:4.12'
    testImplementation 'org.mockito:mockito-core:1.10.19'
    androidTestImplementation 'com.android.support:support-annotations:28.0.0'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    implementation 'com.android.support:support-media-compat:28.0.0'
    implementation "android.arch.lifecycle:viewmodel:1.1.1"

    implementation 'android.arch.navigation:navigation-fragment:1.0.0'
    implementation 'android.arch.navigation:navigation-ui:1.0.0'

}

Answer 3

Run it with --stacktrace or --info or --debug to see more log outputs information from the terminal for example: ./gradlew compileDebugJavaWithJavac --debug.

You wi be able to see more info on when and where it stopped the task and why it failed.

Answer 4

There is problem with 'com.google.firebase:firebase-core:16.0.8' library , when I upgraded it in app/gradle , it solved the problem for me.

Answer 5

Try to update latest versions:

1. RxJava: io.reactivex.rxjava2:rxjava
2. RxAndroid: io.reactivex.rxjava2:rxandroid

Then, AndroidStudio -> File -> invalidate Cashes/Restart.

It helped me.