error: package android.support.v7.app does not exist

Question

i'm going to integrate firebase to my android project, but after following the tutorial i found that this error showing up error: package android.support.v7.app does not exist. i tried to clean the project,and i checked update in android . this is my build.gradle [module ]

apply plugin: 'com.android.application'


android {
compileSdkVersion 28

defaultConfig {
    applicationId "com.example.myapplication"
    minSdkVersion 15
    targetSdkVersion 28
    versionCode 1
    versionName "1.0"
    testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}
buildTypes {
    release {
        minifyEnabled false
        proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
    }
}
}
dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation 'com.android.support:appcompat-v7:28.0.0'
implementation 'com.android.support.constraint:constraint-layout:1.1.3'
implementation 'com.android.support:design:28.0.0'
testImplementation 'junit:junit:4.12'
  androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 
'com.android.support.test.espresso:espresso-core:3.0.2'
implementation 'com.google.android.gms:play-services-auth:17.0.0'

   }

and this my build.gradle [ project ]

buildscript {
repositories {
    google()
    jcenter()

}
dependencies {
    classpath 'com.android.tools.build:gradle:3.4.1'
}
}

allprojects {
repositories {
    google()
    jcenter()

}
}

task clean(type: Delete) {
delete rootProject.buildDir
}

please help to solve this problem i spent all this day looking for a solution . thank you

Answer 1

For latest version (3.4 or higher) of Android Studio

Instead of

import android.support.v7.app.AppcompatActivity

Use this

import androidx.appcompat.app.AppcompatActivity

In MainActivity.java or in main java file

Answer 2

如果你想使用'com.google.android.gms:play-services-auth:17.0.0' （17.0.0 版本）或者你不想迁移 AndroidX 使用 16.0 版本，我认为你应该迁移到 AndroidX .0 implementation 'com.google.android.gms:play-services-auth:16.0.0'

Answer 3

AppcompatActivity 中的 c 必须为大写：

import androidx.appcompat.app.AppCompatActivity