Java 我在null对象上获取错误getApplicationContext

我对GoogleSignIn.GetLastSignedAccount方法（此）有问题。 此方法在null对象引用上的logcat:android.content.Context.getApplicationContext（）中给我始终错误

我的代码：

public class TwoComputerGame extends AppCompatActivity {

  @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        getSupportActionBar().hide();
        setContentView(R.layout.activity_two_computer_game);
}

 public void updateLiderboard() {
            if (GoogleSignIn.getLastSignedInAccount(this) != null) {
//do something
}
}

从logcat：

1618240421.966 13827-13827/com.animalbiznes E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.animalbiznes, PID: 13827
    java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.Context android.content.Context.getApplicationContext()' on a null object reference
        at android.content.ContextWrapper.getApplicationContext(ContextWrapper.java:122)
        at com.google.android.gms.auth.api.signin.internal.zzq.zzd(com.google.android.gms:play-services-auth@@19.0.0:6)
        at com.google.android.gms.auth.api.signin.GoogleSignIn.getLastSignedInAccount(com.google.android.gms:play-services-auth@@19.0.0:11)
        at com.animalbiznes.TwoComputerGame.updateLiderboard(TwoComputerGame.java:2213)
        at com.animalbiznes.KolejPrzeciwnika$1$1$11$1.onFinish(KolejPrzeciwnika.java:281)
        at android.os.CountDownTimer$1.handleMessage(CountDownTimer.java:127)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:223)
        at android.app.ActivityThread.main(ActivityThread.java:7656)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)

---

问题在于

onFinish（）

-您是否自己实例化了

TwoComputerGame

？