android - 无法引用 ((MainActivity) getApplication()).getTracker(MainActivity.TrackerName.APP_TRACKER);

Question

我正在尝试将 Google Analytics 集成到我的应用程序中，并遵循来自 here 的教程一切就绪:

我有一个 MainActivity，它扩展了 Activity 并附加了三个 Tab Fragments，我在这个 Activity 中初始化代码如下:

private static final String PROPERTY_ID = "UA-xxxxxx";

    //Logging TAG
    private static final String TAG = "MyApp";

    public static int GENERAL_TRACKER = 0;

    public enum TrackerName {
        APP_TRACKER, 
        GLOBAL_TRACKER, 
        ECOMMERCE_TRACKER,
    }

    HashMap<TrackerName, Tracker> mTrackers = new HashMap<TrackerName, Tracker>();

    public MainActivity() {
        super();
    }

    synchronized Tracker getTracker(TrackerName trackerId) {
        if (!mTrackers.containsKey(trackerId)) {

            GoogleAnalytics analytics = GoogleAnalytics.getInstance(this);
            Tracker t = (trackerId == TrackerName.APP_TRACKER) ? analytics.newTracker(R.xml.app_tracker)
                    : (trackerId == TrackerName.GLOBAL_TRACKER) ? analytics.newTracker(PROPERTY_ID)
                            : analytics.newTracker(R.xml.ecommerce_tracker);
                    mTrackers.put(trackerId, t);

        }
        return mTrackers.get(trackerId);
    }

现在在我尝试执行的选项卡之一中:

((MainActivity) getApplication()).getTracker(MainActivity.TrackerName.APP_TRACKER);

但是我得到以下信息:

无法在上述代码行中从 Application 转换为 MainActivity。有什么提示吗？我尝试在其中使用它的 fragment 具有以下签名:

public class FragmentTab1 extends Fragment

Answer 1

如果您在 fragment 内调用它，也许您需要改为调用 getActivity？

((MainActivity) getActivity()).getTracker(MainActivity.TrackerName.APP_TRACKER);