Google drive api 错误：无法解析符号mGoogleApiClient

所以我正在尝试将google drive连接到android studio。我在MainActivity.java文件中有以下代码，它给了我一个错误。感谢您的帮助

package com.example.malik.shoutout;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import com.google.android.gms.drive.Drive;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.common.api.GoogleApiClient.ConnectionCallbacks;
import com.google.android.gms.common.api.GoogleApiClient.OnConnectionFailedListener;
import com.google.android.gms.location.LocationListener;
import com.google.android.gms.location.LocationRequest;
import com.google.android.gms.location.LocationServices;

public abstract class MainActivity extends AppCompatActivity
    implements GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener
{

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    mGoogleApiClient = new GoogleApiClient.Builder(this)
            .addApi(Drive.API)
            .addScope(Drive.SCOPE_FILE)
            .addConnectionCallbacks(this)
            .addOnConnectionFailedListener(this)
            .build();

    setContentView(R.layout.activity_main);
}
}

---

您还没有声明变量mGoogleApiClient

我解决了添加以下内容的问题：

GoogleApiClient mGoogleApiClient

这是我的完整代码：

GoogleApiClient mGoogleApiClient = new GoogleApiClient.Builder(this)
                .enableAutoManage(this, (GoogleApiClient.OnConnectionFailedListener) this)
                .addApi(Auth.GOOGLE_SIGN_IN_API, gso)
                .build();

---

您是否在

build.gradle

文件中更新/添加了Google Play Services依赖项并清理/重建了您的项目？API和gso中Auth.Google\u SIGN\u的价值是什么？