嘿，我只是碰到了这个问题也。我没有发现太大的帮助，所以我做了很多的阅读和发现（https://developer.android.com/google/auth/api-client.html ）在小记的GooglePlayServices API是德precated，每个人都必须迁移到GoogleApi代替。

  

请注意：如果你有一个现有的应用程序，连接到谷歌播放   与GooglePlayServicesClient的子类服务，你应该   一旦迁移到GoogleApiClient尽可能

我觉得Android的工作室一直没有更新，自动输入新的API，而不是旧的，后来在发展增加了登录活动时。
因此，任何依赖GooglePlayServices也必须更新，包括PlusClient和一帮他人。

我见过的迁移在互联网上的工具，但它可能只是使事情更容易做到这一点吧。希望这可以帮助。

I have added a login activity to my app with android studio however I am running into these errors:

Error:(11, 37) error: cannot find symbol class GooglePlayServicesClient

Error:(13, 35) error: cannot find symbol class PlusClient

Error:(20, 44) error: package GooglePlayServicesClient does not exist

Error:(21, 33) error: package GooglePlayServicesClient does not exist

Error:(35, 13) error: cannot find symbol class PlusClient

Error:(279, 12) error: cannot find symbol class PlusClient

Error:(78, 31) error: package PlusClient does not exist

Error:(160, 65) error: package PlusClient does not exist

Error:(239, 5) error: method does not override or implement a method from a supertype

Error:(249, 5) error: method does not override or implement a method from a supertype

Error:(262, 5) error: method does not override or implement a method from a supertype

I have already installed google play services in my SDK manager so I'm not sure why it's telling me the package doesn't exist.

EDIT: Gradle file:

apply plugin: 'com.android.application'

android {
    compileSdkVersion 22
    buildToolsVersion "22.0.1"

    defaultConfig {
        applicationId "com.example.tyler.titanaid"
        minSdkVersion 15
        targetSdkVersion 22
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'com.android.support:appcompat-v7:22.0.0'
    compile 'com.google.android.gms:play-services:7.0.0'
}

Hey I just ran into this problem also. I didn't find much help so I did a lot of reading and found ( https://developer.android.com/google/auth/api-client.html ) in a small note that the GooglePlayServices API is deprecated and everyone must migrate to GoogleApi instead.

Note: If you have an existing app that connects to Google Play services with a subclass of GooglePlayServicesClient, you should migrate to GoogleApiClient as soon as possible.

I guess Android Studio has not been updated to automatically input the new API instead of the old one, when adding a login activity later in development.
So anything that relies on GooglePlayServices must also be updated, including PlusClient and a bunch of others.

I've seen migrating tools on the Internet but it might just make things easier to do it yourself. Hope this helps.