[英]Android Fragments Overlapping each other
在我的应用程序中,我有两个片段: FragmentA
和FragmentB
,它们是通过SlidingMenu
从MainActivity
加载的。
显示FragmentB
,它将立即在后台启动AsyncTask
来从服务器加载数据。 激活过程SwipeRefreshLayout
向用户反映了加载过程。
加载完成后,借助于传递给MyAsyncClass
的委托,使用加载的数据刷新FragmentB
的UI。
我现在面临以下问题: processFinish
我的委托中的processFinish
,我将借助swipeRefreshLayout.setRefreshing(false)
停止SwipeRefreshLayout
的刷新。 如果用户要回FragmentA
而后台任务还在进行中,它出现在的情况下,约20%,即FragmentB
仍处于后台FragmentA
在用户界面(见下图)。
如您在图像中所看到的,显示了FragmentA
(文本“尚未播放曲目”来自FragmentA
),但是在背景中您仍然可以看到FragmentB
。
如前所述,这并不是100%的情况,因此这不应是背景/透明度问题。 如果我注释掉swipeRefreshLayout.setRefreshing(false)
,那么该问题就不会重现,但是以某种方式我需要停止SwipeRefreshLayout
以防用户停留在FragmentB
。
任何想法导致这种行为的原因吗?
AsyncResponse接口:
public interface AsyncResponse {
void processFinish(String result);
}
FragmentB级:
public class FragmentB extends MyFragment implements SwipeRefreshLayout.OnRefreshListener, AsyncResponse {
private SwipeRefreshLayout swipeRefreshLayout;
private View view;
private RecyclerView recyclerView;
public FragmentB () {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
view = inflater.inflate(R.layout.songs_list, container, false);
swipeRefreshLayout = (SwipeRefreshLayout) view.findViewById(R.id.swipe_refresh_layout);
swipeRefreshLayout.setOnRefreshListener(this);
swipeRefreshLayout.setColorSchemeColors(getResources().getColor(R.color.colorPrimary));
// Set the adapter
Context context = view.getContext();
recyclerView = (RecyclerView) view.findViewById(R.id.listinclude);
recyclerView.setLayoutManager(new LinearLayoutManager(context));
recyclerView.addItemDecoration(new DividerItemDecoration(getActivity(), R.drawable.divider));
List<Song> songsList = databaseHandler.getAllSongs();
setVisibilities(songsList);
this.recyclerViewAdapter = new RecyclerViewAdapter(songsList, mListener, false, false);
recyclerView.setAdapter(this.recyclerViewAdapter);
swipeRefreshLayout.setRefreshing(true);
receive();
return view;
}
private void setVisibilities(List<Song> songsList) {
ViewFlipper viewFlipper = (ViewFlipper) view.findViewById(R.id.viewFlipper);
if (songsList.isEmpty() && viewFlipper.getDisplayedChild() == 0) {
viewFlipper.setDisplayedChild(1);
} else if (!songsList.isEmpty() && viewFlipper.getDisplayedChild() == 1) {
viewFlipper.setDisplayedChild(0);
}
}
@Override
public void onRefresh() {
if (MyOnlineHelper.isOnline(getContext())) {
receive();
} else {
swipeRefreshLayout.setRefreshing(false);
}
}
private void receive() {
new MyAsyncClass(this, getContext()).execute("receiving");
}
@Override
public void processFinish(String output) {
// refreshUI
swipeRefreshLayout.setRefreshing(false);
}
}
FragmentA级:
public class FragmentA extends MyFragment implements AsyncResponse {
private View view;
private RecyclerView recyclerView;
public FragmentA() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
List<Song> songsList = myDatabaseHandler.getAllSongs();
view = inflater.inflate(R.layout.home_list, container, false);
// Set the adapter
Context context = view.getContext();
recyclerView = (RecyclerView) view.findViewById(R.id.listinclude);
recyclerView.setLayoutManager(new LinearLayoutManager(context));
recyclerView.addItemDecoration(new DividerItemDecoration(getActivity(), R.drawable.divider));
setVisibilities(songsList);
this.recyclerViewAdapter = new RecyclerViewAdapter(songsList, mListener, false, true);
recyclerView.setAdapter(this.recyclerViewAdapter);
return view;
}
@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
}
private void setVisibilities(List<Song> songsList) {
ViewFlipper viewFlipper = (ViewFlipper) view.findViewById(R.id.viewFlipper);
if (songsList.isEmpty() && viewFlipper.getDisplayedChild() == 0) {
viewFlipper.setDisplayedChild(1);
} else if (!songsList.isEmpty() && viewFlipper.getDisplayedChild() == 1) {
viewFlipper.setDisplayedChild(0);
}
}
@Override
public void processFinish(String output) {
// does something
}
}
MyAsyncClass:
public class MyAsyncClass extends AsyncTask<String, Integer, String> {
private AsyncResponse delegate;
private Context mContext;
private MyDatabaseHandler myDatabaseHandler;
public MyAsyncClass(AsyncResponse delegate, Context context) {
this.delegate = delegate;
this.mContext = context;
}
@Override
protected String doInBackground(String... params) {
// calling webservice and writing it to the database
}
@Override
protected void onPostExecute(String result) {
delegate.processFinish(result);
super.onPostExecute(result);
}
}
MainActivity级:
public class MainActivity extends AppCompatActivity implements MyFragment.OnListFragmentInteractionListener, AsyncResponse {
private FragmentA fragmentA = new FragmentA();
private FragmentB fragmentB;
private NavigationView navigationView;
private DrawerLayout drawer;
private Toolbar toolbar;
// index to identify current nav menu item
private static int navItemIndex = 0;
public static String CURRENT_TAG = MyConstants.TAG_FRAGMENT_A;
// toolbar titles respected to selected nav menu item
private String[] activityTitles;
// flag to load home fragment when user presses back key
private Handler mHandler;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
fragmentA.setDatabaseHandler(this.myDatabaseHandler);
// Init UI
toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
mHandler = new Handler();
drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
navigationView = (NavigationView) findViewById(R.id.nav_view);
fabSendButton = (FloatingActionButton) findViewById(R.id.fab);
// Navigation view header
navHeader = navigationView.getHeaderView(0);
// load toolbar titles from string resources
activityTitles = getResources().getStringArray(R.array.sliding_menu_item_activity_titles);
// initializing navigation menu
setUpNavigationView();
if (savedInstanceState == null) {
navItemIndex = 0;
CURRENT_TAG = MyConstants.TAG_FRAGMENT_A;
loadHomeFragment();
}
}
/***
* Returns respected fragment that user
* selected from navigation menu
*/
private void loadHomeFragment() {
// set toolbar title
setToolbarTitle();
// if user select the current navigation menu again, don't do anything
// just close the navigation drawer
if (getSupportFragmentManager().findFragmentByTag(CURRENT_TAG) != null) {
drawer.closeDrawers();
return;
}
// Sometimes, when fragment has huge data, screen seems hanging
// when switching between navigation menus
// So using runnable, the fragment is loaded with cross fade effect
// This effect can be seen in GMail app
Runnable mPendingRunnable = new Runnable() {
@Override
public void run() {
// update the activity_main_header_with_item content by replacing fragments
Fragment fragment = getFragment();
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.setCustomAnimations(android.R.anim.fade_in, android.R.anim.fade_out);
fragmentTransaction.replace(R.id.frame, fragment, CURRENT_TAG);
fragmentTransaction.commit();
}
};
// If mPendingRunnable is not null, then add to the message queue
if (mPendingRunnable != null) {
mHandler.post(mPendingRunnable);
}
//Closing drawer on item click
drawer.closeDrawers();
// refresh toolbar menu
invalidateOptionsMenu();
}
private Fragment getFragment() {
switch (navItemIndex) {
case 0:
return this.fragmentA;
case 1:
if (fragmentB == null) {
fragmentB = new FragmentB();
fragmentB.setDatabaseHandler(this.myDatabaseHandler);
}
return fragmentB;
default:
return this.fragmentA;
}
}
private void setToolbarTitle() {
getSupportActionBar().setTitle(activityTitles[navItemIndex]);
}
private void setUpNavigationView() {
//Setting Navigation View Item Selected Listener to handle the item click of the navigation menu
navigationView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {
// This method will trigger on item Click of navigation menu
@Override
public boolean onNavigationItemSelected(MenuItem menuItem) {
//Check to see which item was being clicked and perform appropriate action
switch (menuItem.getItemId()) {
//Replacing the activity_main_header_with_item content with ContentFragment Which is our Inbox View;
case R.id.nav_A:
navItemIndex = 0;
CURRENT_TAG = MyConstants.TAG_FRAGMENT_A;
break;
case R.id.nav_B:
navItemIndex = 1;
CURRENT_TAG = MyConstants.TAG_FRAGMENT_B;
break;
default:
navItemIndex = 0;
}
loadHomeFragment();
return true;
}
});
ActionBarDrawerToggle actionBarDrawerToggle = new ActionBarDrawerToggle(this, drawer, toolbar, R.string.openDrawer, R.string.closeDrawer) {
@Override
public void onDrawerClosed(View drawerView) {
// Code here will be triggered once the drawer closes as we dont want anything to happen so we leave this blank
super.onDrawerClosed(drawerView);
}
@Override
public void onDrawerOpened(View drawerView) {
// Code here will be triggered once the drawer open as we dont want anything to happen so we leave this blank
super.onDrawerOpened(drawerView);
}
};
//Setting the actionbarToggle to drawer layout
drawer.setDrawerListener(actionBarDrawerToggle);
//calling sync state is necessary or else your hamburger icon wont show up
actionBarDrawerToggle.syncState();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main_header_with_item, menu);
return true;
}
}
感谢Prsnth Gettin High和这篇文章( 在刷新过程中使用SwipeRefreshLayout切换片段时,片段会冻结,但实际上仍然可以正常工作 ),将SwipeRefreshLayout包裹在FrameLayout中会有所帮助,例如:
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v4.widget.SwipeRefreshLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/swipe_refresh_layout"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ViewFlipper
android:id="@+id/viewFlipper"
android:layout_width="match_parent"
android:layout_height="match_parent">
<include
android:id="@+id/listinclude"
layout="@layout/list"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:visibility="visible"/>
<include
android:id="@+id/emptyinclude"
layout="@layout/fragment_empty"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:visibility="visible"/>
</ViewFlipper>
</android.support.v4.widget.SwipeRefreshLayout>
</FrameLayout>
尝试重用视图。 它可能会解决此问题。
`@Override public View onCreateView(LayoutInflater inflater,ViewGroup container,Bundle savedInstanceState){
if(view == null){view = inflater.inflate(R.layout.songs_list,container,false);}`
尝试将片段对象向下转换为特定片段。
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
Fragment fragment = getFragment();
FragmentA fragA;
FragmentB fragB;
if(fragment intanceof FragmentA)
{
fragA=(FragmentA) fragment;
fragmentTransaction.setCustomAnimations(android.R.anim.fade_in, android.R.anim.fade_out);
fragmentTransaction.replace(R.id.frame, fragA, FragmentA.TAG);
}
if(fragment instanceof FragmentB)
{
fragB=(FragmentB) fragment;
fragmentTransaction.setCustomAnimations(android.R.anim.fade_in, android.R.anim.fade_out);
fragmentTransaction.replace(R.id.frame, fragB, FragmentB.TAG);
}
fragmentTransaction.commit();
请问您为什么要使用可运行的交换片段?
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