MapFragment在框架内，当父活动开始时，onPause MapFragment变为null

Question

我有一个活动ACTIVITY=>Fragment=>MapFragment

在活动的onPause上，MapFragment变为null。

下面是我使用的方法：

 private MapFragment getMapFragment() {
        FragmentManager fm = null;

        Log.d("", "sdk: " + Build.VERSION.SDK_INT);
        Log.d("", "release: " + Build.VERSION.RELEASE);

        if (Build.VERSION.SDK_INT < 21) {
            Log.d("framentmgr", "using getFragmentManager");
            fm = getFragmentManager();
        } else {
            Log.d("framentmgr", "using getChildFragmentManager");
            fm = getChildFragmentManager();
        }
//        fm = getChildFragmentManager();
        fm.beginTransaction();

        MapFragment mapFragment = (MapFragment) fm.findFragmentById(R.id.fragment_map);


        return mapFragment;
    }

为什么会发生这种情况，有什么解决方案或原因吗？

Answer 1

谢谢，但我也收到了同样的错误。所以我现在用一种巧妙的方式解决了这个问题，在另一个类中将MapFragment作为公共静态变量。

public static MapFragment mapFragment;

在Fragment类中

private MapFragment getMapFragment() {
        FragmentManager fm = null;

        Log.d("", "sdk: " + Build.VERSION.SDK_INT);
        Log.d("", "release: " + Build.VERSION.RELEASE);

        if (Build.VERSION.SDK_INT < 21) {
            Log.d("framentmgr", "using getFragmentManager");
            fm = getFragmentManager();
        } else {
            Log.d("framentmgr", "using getChildFragmentManager");
            fm = getChildFragmentManager();
        }
//        fm = getChildFragmentManager();
        fm.beginTransaction();

        MapFragment mapFragment = null;
        if(MainActivity.mapFragment==null)
            mapFragment = (MapFragment) fm.findFragmentById(R.id.fragment_map);
        else
            return MainActivity.mapFragment;


        return mapFragment;
    }