实现'androidx.appcompat：appcompat：1.0.0'

Question

同步问题

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'androidx.appcompat:appcompat:1.0.0'
    implementation 'androidx.legacy:legacy-support-v4:1.0.0'
    implementation 'androidx.constraintlayout:constraintlayout:1.1.2'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'androidx.test:runner:1.1.0'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.1.0'
    implementation 'com.google.android.material:material:1.0.0-rc01'
    implementation 'com.google.firebase:firebase-core:17.0.0'
    implementation 'com.google.firebase:firebase-messaging:19.0.1'
}
apply plugin: 'com.google.gms.google-services'

在将我的项目迁移到AndroidX时，错误开始出现在之前创建的所有java文件中