Question

我使用了Viewpager嵌入式fragment，并且适应了夜间模式。当我打开夜间模式时，我发现该活动已重建，并且片段当然也是。

数字模式：UiModeManager.setNightMode(android.app.UiModeManager.MODE_NIGHT_YES);

我认为他们正在重新加载专用于夜间模式的资源并重新加载视图。但是，当我初始化recyclerView（在其中一个片段中）时，它为null。

如果我将所有初始化都放在onCreateView中，则看起来它已正常初始化。但我从活动中称它为null

MainActivity：url

// in MainActivity
if (isDarkMode) {
        PreferenceUtil.getDefault(MainActivity.this)
                .edit().putBoolean(Values.SharedPrefsTag.DARK_MODE, false).apply();
        UiModeManager UiModeManager = (UiModeManager) getSystemService(Context.UI_MODE_SERVICE);
        UiModeManager.setNightMode(android.app.UiModeManager.MODE_NIGHT_NO);
        mMainBinding.navigationView.getMenu().findItem(R.id.dart_mode).setChecked(false);
    } else {
        PreferenceUtil.getDefault(MainActivity.this)
                .edit().putBoolean(Values.SharedPrefsTag.DARK_MODE, true).apply();
        UiModeManager UiModeManager = (UiModeManager) getSystemService(Context.UI_MODE_SERVICE);
        UiModeManager.setNightMode(android.app.UiModeManager.MODE_NIGHT_YES);
        mMainBinding.navigationView.getMenu().findItem(R.id.dart_mode).setChecked(true);
    }

public final class MusicListFragment extends BaseListFragment {

    public static final String TAG = "MusicListFragment";

    public FragmentMusicListBinding mMusicListBinding;

    private MyRecyclerAdapter adapter;

    private MainActivity mActivity;

    @Override
    public void reloadData() {
        Data.sMusicItems.clear();
        Data.sMusicItemsBackUp.clear();
        adapter.notifyDataSetChanged();
        loadData();
    }

    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        mMusicListBinding = DataBindingUtil.inflate(inflater, R.layout.fragment_music_list, container, false);
        loadData();
        return mMusicListBinding.getRoot();
    }


    public void initRecyclerView() {
        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(mActivity) {
            @Override
            protected int getExtraLayoutSpace(RecyclerView.State state) {
                return 700;
            }
        };
        linearLayoutManager.setItemPrefetchEnabled(true);
        linearLayoutManager.setInitialPrefetchItemCount(15);

        adapter = new MyRecyclerAdapter(mActivity, Data.sMusicItems
                , new MyRecyclerAdapter.Config(PreferenceUtil.getDefault(mActivity).getInt(Values.SharedPrefsTag
                .RECYCLER_VIEW_ITEM_STYLE, 0), true));
        mMusicListBinding.includeRecycler.recyclerView.setLayoutManager(linearLayoutManager);
        mMusicListBinding.includeRecycler.recyclerView.setHasFixedSize(true);
        mMusicListBinding.includeRecycler.recyclerView.setItemViewCacheSize(15);
        mMusicListBinding.includeRecycler.recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrollStateChanged(@NonNull RecyclerView recyclerView, int newState) {
                if (newState == RecyclerView.SCROLL_STATE_IDLE) {
                    GlideApp.with(mActivity).resumeRequests();
                } else {
                    GlideApp.with(mActivity).pauseRequests();
                }
            }
        });
        mMusicListBinding.includeRecycler.recyclerView.setAdapter(adapter);

    }
}

当我设置夜间模式时，MainActivity将调用initRecyclerView()的{{1}}方法，但是他将具有空指针。但是对我来说，正常启动应用程序是正常的。

设置夜间模式时，为什么活动下的片段中的绑定显示为空？

0 个答案: