在Android中使用Cloud Save时发生NullPointerException

Question

我需要初始化AppStateClient才能使用Cloud来保存和加载数据。 接下来，我要做：

public Constructor() {
(1) private GameHelper aHelper = new GameHelper(this);    
(2) aHelper.setup(this, GameHelper.CLIENT_APPSTATE | GameHelper.CLIENT_GAMES);
(3) private AppStateClient mHelper = aHelper.getAppStateClient();
}

但是在第二个字符串中，我总是得到NullPointerException。 在Goggle的GameHelper类中，它崩溃了：

 mGamesClient = new GamesClient.Builder(getContext(), this, this)
                    .setGravityForPopups(Gravity.TOP | Gravity.CENTER_HORIZONTAL)
                    .setScopes(mScopes)
                    .create();
and on:  

mAppStateClient = new AppStateClient.Builder(getContext(), this, this)
                    .setScopes(mScopes)
                    .create();

我做错了什么？

我也在应用程序中使用aHelper变量来获得成就和排行榜，并且一切正常。

Answer 1

问题已解决。

public Constructor() {
 private GameHelper aHelper = new GameHelper(this);    
 aHelper.setup(this, GameHelper.CLIENT_APPSTATE | GameHelper.CLIENT_GAMES);
 private AppStateClient mHelper = aHelper.getAppStateClient();
}

此代码需要调用onCreate（Bundle savedInstanceState）而不是类的构造函数

@Override
  public void onCreate(Bundle savedInstanceState) {
private GameHelper aHelper = new GameHelper(this);    
     aHelper.setup(this, GameHelper.CLIENT_APPSTATE | GameHelper.CLIENT_GAMES);
     private AppStateClient mHelper = aHelper.getAppStateClient();
}