Question

我无法将高分数提交到Android排行榜。现在排行榜是空的，没有提交任何内容。我有一个需要提交的int“oldScore”。现在我正在尝试一段代码来提交它，但活动在被调用时崩溃了。我的代码：

public class GameOver extends BaseGameActivity implements GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener {

    private GoogleApiClient mGoogleApiClient;
    public static int score;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_game_over);

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

        int newScore = GameOver.score;

        SharedPreferences prefs = this.getSharedPreferences("myPrefsKey", Context.MODE_PRIVATE);

        int oldScore = prefs.getInt("key", 0);
        if (newScore > oldScore) {
            SharedPreferences.Editor edit = prefs.edit();
            edit.putInt("key", newScore);
            edit.commit();

            EditText HighScore = (EditText) findViewById(R.id.HighScoreT);
            HighScore.setText("" + newScore);
        } else {
            EditText HighScore = (EditText) findViewById(R.id.HighScoreT);
            HighScore.setText("" + oldScore);
            Games.Leaderboards.submitScoreImmediate(getApiClient(),String.valueOf(R.string.number_guesses_leaderboard), oldScore);
        }
    }

logcat的：

引起：java.lang.NullPointerException：尝试调用接口方法'无效 com.google.android.gms.common.api.GoogleApiClient.connect（）'上的null 对象参考

Answer 1

声明

mGoogleApiClient.connect();

应在mGoogleApiClient实例化后出现

Answer 2

您正在调用方法

connect()

对象上的

mGoogleApiClient

没有实例化

你需要先写这个，

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

那么，

mGoogleApiClient.connect();

Answer 3

在初始化connect()引用之后， {em>}之后才能调用mGoogleApiClient。像，

// mGoogleApiClient.connect(); mGoogleApiClient = new GoogleApiClient.Builder(this) .addApi(Drive.API) .addScope(Drive.SCOPE_FILE) .addConnectionCallbacks(this) .addOnConnectionFailedListener(this) .build(); mGoogleApiClient.connect(); // <-- move to here.

Answer 4

试试这个过程：在加载内容视图之前分配Google客户端：

private GoogleApiClient mGoogleApiClient;
public static int score;

@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_game_over);
}

添加覆盖onStart并连接谷歌客户端。

@Override
     public void onStart() {
        super.onStart();
        mGoogleApiClient.connect();
    }

@Override
public void onStop() {
    super.onStop();
    mGoogleApiClient.disconnect();
}

引发者：java.lang.NullPointerException：尝试在null对象引用上调用接口方法

4 个答案: