I have a simple layout containing a VideoView.
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#color/black"
android:gravity="center" >
<VideoView
android:id="#+id/videoPlayer"
android:layout_width="fill_parent"
android:layout_height="fill_parent"/>
</RelativeLayout>
The Activity that uses this layout creates a Fragment to start the VideoView
public class VideoPlayerActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_video_player);
createNewWorkerFragment();
}
private void createNewWorkerFragment() {
FragmentManager fragmentManager = getFragmentManager();
VideoPlayerActivityWorkerFragment workerFragment = (VideoPlayerActivityWorkerFragment)fragmentManager.findFragmentByTag(VideoPlayerActivityWorkerFragment.Name);
if (workerFragment == null) {
workerFragment = new VideoPlayerActivityWorkerFragment();
fragmentManager.beginTransaction()
.add(workerFragment, VideoPlayerActivityWorkerFragment.Name)
.commit();
}
}
}
The VideoPlayerActivityWorkerFragment is as follows:
public class VideoPlayerActivityWorkerFragment extends Fragment {
public static String Name = "VideoPlayerActivityWorker";
private VideoView mVideoPlayer;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setRetainInstance(true);
mVideoPlayer = (VideoView) mActivity.findViewById(R.id.videoPlayer);
mVideoPlayer.setVideoPath(mActivity.getIntent().getExtras().getString("path"));
MediaController controller = new MediaController(mActivity);
controller.setAnchorView(mVideoPlayer);
mVideoPlayer.setMediaController(controller);
mVideoPlayer.requestFocus();
mVideoPlayer.start();
}
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
mActivity = activity;
}
#Override
public void onDetach() {
super.onDetach();
mActivity = null;
}
}
This is the issue I'm having, when the VideoPlayerActivity starts the VideoPlayerActivityWorkerFragment is created and the VideoView starts playing, however when I rotate the device the video stops and will not play, the entire View seems gone from the layout. Due to setRetainInstance(true); I thought that the VideoView would continue to play. Can someone let me know what I'm doing wrong? I have used this pattern elsewhere (not with a VideoView) and it successfully allows rotation to happen.
I am unwilling to use the android:configChanges="keyboardHidden|orientation|screenSize" or similar methods, I would like to handle the orientation change with Fragments.
Thank you in advance for your help.
Edit
I ended up picking the solution I did because it works. The videoview and controller need to be recreated each time onCreateView is called and the playback position needs to be set in onResume and recored in onPause. However, the playback is choppy during the rotation. The solution is not optimal but it does work.
See mVideoPlayer = (VideoView) mActivity.findViewById(R.id.videoPlayer);
Your VideoView is created by the activity which is being destroyed and recreated on rotation. This means a new R.id.videoPlayer VideoView is being created. So your local mVideoPlayer is just being overwritten in your above line. Your fragment needs to create the VideoView in its onCreateView() method. Even then, this may not suffice. Because Views are inherently linked with their owning Context. Perhaps an explicit pause, detect and attach, play of the view would be a better way to go.
Here are some observations:
1.First of all, you should know that even if a fragment is retained the activity gets distroyed.
As a result, the onCreate() method of activity, where you add the fragment, is called every time thus resulting in multple fragments overlaping each other.
In VideoPlayerActivity you need a mechanism to determine whether the activity is created for the first time, or is re-created due to a configuration change.
You can solve this problem by putting a flag in onSaveInstanceState() and then checking the savedInstanceState in onCreate(). If it's null, it means the activity is created for the first time, so only now you can add the fragment.
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
if (savedInstanceState == null) {
createNewWorkerFragment();
}
}
// ....
#Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putBoolean("fragment_added", true);
}
2.Secondly, in VideoPlayerActivityWorkerFragment you are refering to the VideoView declared in the activity:
mVideoPlayer = (VideoView) mActivity.findViewById(R.id.videoPlayer);
which gets destroyed when the screen is rotated.
What you should do, is to extract that VideoView and put it in a separate layout file that will be inflated by the fragment in the onCreateView() method.
But even here you may have some troubles. Despide the fact that setRetainInstance(true) is called, onCreateView() is called every time on screen orientation, thus resulting in re-inflation of your layout.
The solution would be to inflate the layout in onCreateView() only once:
public class VideoPlayerActivityWorkerFragment extends Fragment {
private View view;
//.....
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
if (view == null) {
view = inflater.inflate(R.layout.my_video_view, container, false);
mVideoPlayer = (VideoView) view.findViewById(R.id.videoPlayer);
// .....
} else {
// If we are returning from a configuration change:
// "view" is still attached to the previous view hierarchy
// so we need to remove it and re-attach it to the current one
ViewGroup parent = (ViewGroup) view.getParent();
parent.removeView(view);
}
return view;
}
}
}
If all the above said does not make sense for you, reserve some time to play with fragments, especially inflation of a layout in a fragment, then come back and read this answer again.
Related
I have an app that has a main activity that the user can select an item from. That selection brings up a fragment (TracksActivityFragment) that itself is another list. When an item of that list is selected, a fragment is added that is a DialogFragment. So far so good, but when I rotate the device, the AFragment's onCreate() gets called and then the DailogFragment's onCreate() gets called, then it dies with the IllegalStateException saying that it dies on AFragment's Activity line 20 (setContentView).
Here is a part of that Activity with the line in question:
public class TracksActivity extends AppCompatActivity
{
private String mArtistName;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_tracks); //DIES HERE
Here is the onCreate of the fragment
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
if(savedInstanceState != null)
{
//We've got data saved. Reconstitute it
mTrackRowItemList = savedInstanceState.getParcelableArrayList(KEY_ITEMS_LIST);
}
}
The DialogFragment gets created in the TracksFragment like this:
PlayerFragment fragment = PlayerFragment.newInstance(mTrackRowItemList, i, mArtistBitmapFilename);
// The device is smaller, so show the fragment fullscreen
FragmentTransaction transaction = fragMan.beginTransaction();
// For a little polish, specify a transition animation
transaction.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
// To make it fullscreen, use the 'content' root view as the container
// for the fragment, which is always the root view for the activity
transaction.add(android.R.id.content, fragment).addToBackStack(null).commit();
Here is the DialogFragment's onCreate
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
if (savedInstanceState != null)
{
//We've got data saved. Reconstitute it
if (mPlayer != null)
{
mPlayer.seekTo(savedInstanceState.getInt(KEY_SONG_POSITION));
}
}
}
Not sure why it goes back to the TracksFragment since it had the DialogFragment active on rotation, but since that is the case, it would seem like I would need to recreate the entireDialogPlayer object, But it seems to keep this around as the call to its onCreate happens.
Anyone know what it is that needs to be done here?
OK, this was asked before but I discounted the solution...I should not have.
For some reason, Android wants the Tracks layout XML to use a FrameLayout instead of a fragment.
So, just replace fragment with FrameLayout in the layout xml file and all is well.
My fragment is being created twice, even though the activity is only adding the fragment once to the content. This happens when I rotate the screen. Also, everytime the fragment's onCreateView is called, it has lost all of it's variable state.
public class MainActivity extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState == null) { // Checking for recreation
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new AppPanelFragment())
.commit();
}
}
}
onCreate in the activity checks for the null savedInstanceState and only if null will add the fragment so I can't see why the fragment should be created twice? Putting a breakpoint in that if condition tells me that it only ever get's called once so the activity shouldn't be adding the fragment multiple times. However the onCreateView of the fragment still gets called each time orientation changes.
public class AppPanelFragment extends Fragment {
private TextView appNameText;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// This method called several times
View rootView = inflater.inflate(R.layout.fragment_app_panel, container, false);
// 2nd call on this method, appNameText is null, why?
appNameText = (TextView) rootView.findViewById(R.id.app_name);
appNameText.text = "My new App";
return view;
}
I managed to have the variable state persisted using setRetainInstance(true), but is this the real solution? I would expect the fragment to not be created on just an orientation change.
In android, when the phone's orientation is changed, the activity is destroyed and recreated. Now, i believe to fix your problem you can use the fragment manager to check to see if the fragment already exists in the back stack and if it doesn't then create it.
public void onCreated(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState == null) {
mFragmentManager = getSupportFragmentManager();
AppPanelFragment fragment = (AppPanelFragment)mFragmentManager.findFragmentById(R.id.fagment_id);
if(fragment == null) {
//do your fragment creation
}
}
}
P.S. I haven't tested this but it should work once you provide the right fragment's id in the findFragmentById method.
The Fragment lifecycle is very similar to an Activity. By default, yes, they will be re-created during a configuration change just like an Activity does. That's expected behavior. Even with setRetainInstance(true) (which I would say to use with extreme caution if it contains a UI) your View will be destroyed and re-created, but in that case your Fragment instance will not be destroyed -- just the View.
I know it is a bit late to answer, but using The Code Pimp answer you can do the next thing:
If the fragment exists in the backstack we pop and remove it to add it back (an exception is thrown if it is added back without removing it, saying it already exists).
The fragment variable is a class member variable.
This method will be called in the onCreate method of the Activity:
if (savedInstanceState == null) {
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
if (fragmentManager.findFragmentById(getFragmentActivityLayoutContainerId()) == null) {
fragment = getNewFragmentInstance();
} else {
fragment = fragmentManager.findFragmentById(getFragmentActivityLayoutContainerId());
fragmentTransaction.remove(fragment);
fragmentManager.popBackStack();
fragmentTransaction.commit();
fragmentTransaction = fragmentManager.beginTransaction();
}
fragmentTransaction.add(getFragmentActivityLayoutContainerId(), fragment);
fragmentTransaction.commit();
}
The next code will be called in the fragment itself.
It is a small example for a code you could implement in your fragment to understand how it works. The dummyTV is a simple text view in the center of the fragment that receives text according to orientation (and for that we need a counter).
private TextView dummyTV;
private static int counter = 0;
#Override
protected int getFragmentLayoutId() {
return R.layout.fragment_alerts_view;
}
#Override
protected void saveReferences(View view) {
dummyTV = (TextView) view.findViewById(R.id.fragment_alerts_view_dummy_tv);
}
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
if (savedInstanceState != null) {
dummyTV.setText(savedInstanceState.getString("dummy_string"));
} else {
dummyTV.setText("flip me!");
}
dummyTV.append(" | " + String.valueOf(counter));
}
#Override
public void onSaveInstanceState(Bundle outState) {
outState.putString("dummy_string", counter++ % 2 == 0 ? "landscape" : "portrait");
}
As mentioned, on orientation change, the activity is destroyed and recreated. Also, Fragments(any) are recreated by the system.
To ensure your application restores to previous state, onSaveInstanceState() is called before the activity is destroyed.
So, you can store some information in the onSaveInstanceState() method of an activity and then restore your application to same state on orientation change.
NOTE: You need not create fragments on orientation change, as fragments are recreated.
Example from http://www.mynewsfeed.x10.mx/articles/index.php?id=15:
public class MainActivity extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if ( savedInstanceState == null ){
//Initialize fragments
Fragment example_fragment = new ExampleFragment();
FragmentManager manager = getFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
transaction.add(R.id.container, example_fragment, "Example");
} else{
//control comes to this block only on orientation change.
int postion = savedInstanceState.getInt("position"); //You can retrieve any piece of data you've saved through onSaveInstanceState()
//finding fragments on orientation change
Fragment example_fragment = manager.findFragmentByTag("Example");
//update the fragment so that the application retains its state
example_fragment.setPosition(position); //This method is just an example
}
}
#Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putInt("position", position); //add any information you'd like to save and restore on orientation change.
}
}
I have statically created a fragment (via XML). I'm trying to store the last displayed value in a bundle and display it whenever the app is started next. However I am not able to get it to work. For some reason savedInstanceState is always null.
public class DistanceSetterFragment extends Fragment implements SharedPreferences.OnSharedPreferenceChangeListener {
Distance distance = new Distance();
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
if (savedInstanceState!=null )
{
Log.d(this.getClass().getName(),"onCreate savedInstanceState is NOT null");
}
else
{
Log.d(this.getClass().getName(),"onCreate savedInstanceState is null");
}
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
Log.d(this.getClass().getName(),"Distance "+distance);
if (savedInstanceState!=null )
{
Log.d(this.getClass().getName(),"onCreateView savedInstanceState is NOT null");
}
else
{
Log.d(this.getClass().getName(),"onCreateView savedInstanceState is null");
}
return inflater.inflate(R.layout.fragment_distancesetter, container, false);
}
#Override
public void onSaveInstanceState(Bundle outState)
{
super.onSaveInstanceState(outState);
if (distance!=null) {
Log.d(this.getClass().getName(),"Saving DISTANCE_BEAN "+distance);
outState.putSerializable(Constants.DISTANCE_BEAN, distance);
}
else
{
Log.d(this.getClass().getName(),"Distance BEAN IS NULL");
}
outState.putString("", "");
}
}
Below is the fragment XML declared in my main activity XML
<fragment
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:id="#+id/fragment_distancesetter"
android:layout_below="#id/img_logo_main"
android:name="com.webconfs.xyz.fragments.DistanceSetterFragment"
android:layout_marginLeft="4dp"
android:layout_marginRight="4dp"
/>
As you can see
- I have NOT set setRetainInstance(true) in my Fragment class and
- My fragment XML has an ID associated with it
android:id="#+id/fragment_distancesetter
I had the same problem just now and it was driving me crazy, but as it turns out the fragment was simply being re-added in the activity with every rotation. You didn't add your Activity's code, but you might want to check this is not the case as it's easy to overlook and would explain your problem.
When you put a fragment into an activity statically, the fragment manager will always create a new fragment and attach it to activity. The restoreInstanceState() method will never be called. If you want to do it, you can save state in your activity's restore method, and put save state of your activity to your fragment. Or create fragment dynamically.
We all know that when using ViewPager with Fragment and FragmentPagerAdapter we get 3 Fragment loaded: the visible one, and both on each of its sides.
So, if I have 7 Fragments and I'm iterating through them to see which 3 of them are the ones that are loaded, and by that I mean onCreateView() has already been called, how can I determine this?
EDIT: The Fragment doesn't have to be the one that the ViewPager is showing, just that onCreateView() has already been called.
Well logically, this would be a reasonable test if onCreateView has been called:
myFragment.getView() != null;
Assuming you a have a reference to all of the fragments in the pager iterate, them and check if they have a view.
http://developer.android.com/reference/android/app/Fragment.html#getView()
Update
The above answer assumes that your fragments always create a view, and are not viewless fragments. If they are then I suggest sub classing the fragment like so:
public abstract class SubFragment extends Fragment
{
protected boolean onCreateViewCalled = false;
public boolean hasOnCreateViewBeenCalled()
{
return onCreateViewCalled;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup Container, Bundle state){
onCreateViewCalled = true;
return null;
}
}
Just bear in mind that further sub classes will have to call super or set the flag themselves should they override onCreateView as well.
I added an interface to Fragment. Looks like:
protected OnCreateViewCallback createViewCallback = null;
public void setCreateViewCallback(OnCreateViewCallback createViewCallback) {
this.createViewCallback = createViewCallback;
}
public interface OnCreateViewCallback {
void onCreateView();
}
In my onCreateView():
//initialize your view.
if (createViewCallback != null) {
createViewCallback.onCreateView();
createViewCallback = null;
}
return mainView;
From my activity:
if (ocrFragment.getView() == null) {
ocrFragment.setCreateViewCallback(new MainScreenFragment.OnCreateViewCallback() {
#Override
public void onCreateView() {
ocrFragment.ocrImage(picture, false);
}
});
} else {
ocrFragment.ocrImage(picture, false);
}
If you are trying to perform something after onCreateView is called, use onViewCreated:
Called immediately after onCreateView(LayoutInflater, ViewGroup,
Bundle) has returned, but before any saved state has been restored in
to the view. This gives subclasses a chance to initialize themselves
once they know their view hierarchy has been completely created. The
fragment's view hierarchy is not however attached to its parent at
this point.
public void onViewCreated(View view, Bundle savedInstanceState) {
MyActivity myActivity = (MyActivity) getActivity();
MyActivity.newAsyncTask(mPar);
}
You could also check for Fragment.isVisible() because a Fragment is in visible state when it's in the offscreen page limit of a ViewPager.
Edit: But it just really depends on what you really want to achieve with your question. Perhaps some kind of update to all UIs in your Fragments when their UI is ready?
EDIT:
Just another addition, you could listen to onViewCreated() and set a flag. Or notify your Activity and do further work (getActivity() will return your Activity at this point). But really, better state what you want to accomplish with your question.
We have a web service which serves up an XML file via a HTTP Post.
I am downloading and parsing this xml file into an object to populate some views inside a couple of fragments held in a FragmentPagerAdapter. I get this XML file via an AsyncTask and it tells my fragments the process has finished via a listener interface.
From there, I populate the view inside the fragment with data returned from the web service. This is all fine until the orientation changes. From what I understand, the ViewPager's adapter is supposed to retain the fragments it's created, which is fine, and which I want to happen, and I know the fragment's onCreateView method is still called to return the view. I've spent the last day or so hunting through posts here and the Google docs etc and I can't find a concrete method that lets me do what I want to do: retain the fragment, and it's already populated view so that I can simply restore it when the orientation changes and avoid unneccesary calls to the web service.
Some code snippets:
In the main activities onCreate:
mViewPager = (ViewPager) findViewById(R.id.viewpager);
if (mViewPager != null) {
mViewPager.setAdapter(new PagerAdapter(getSupportFragmentManager()));
}
if (savedInstanceState == null) {
if (CheckCredentials()) {
Refresh(0,0);
} else {
ShowCredentialsDialog(false);
}
}
Refresh method in main activity...
public void Refresh(Integer month, Integer year) {
if (mUpdater == null) {
mUpdater = new UsageUpdater(this);
// mUpdater.setDataListener(this);
}
if (isConnected()) {
mUpdater.Refresh(month, year);
usingCache = false;
mProgress.show();
} else {
mUpdater.RefreshFromCache();
usingCache = true;
}
}
This is the entire Fragment in question, minus some of the UI populating code as it's not important to show the setting of text in textviews etc...
public class SummaryFragment extends Fragment implements Listeners.GetDataListener {
private static final String KEY_UPDATER = "usageupdater";
private UsageUpdater mUpdater;
private Context ctx;
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
this.ctx = activity;
}
private View findViewById(int id) {
return ((Activity)ctx).findViewById(id);
}
public void onGetData() {
// AsyncTask interface method, will be called from onPostExecute.
// Populate view from here
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
super.onCreateView(inflater, container, savedInstanceState);
View view = inflater.inflate(R.layout.fragment_usagesummary, container, false);
mUpdater = (UsageUpdater) getArguments().getSerializable(KEY_UPDATER);
mUpdater.setDataListener(this);
return view;
}
}
If I understand any of this 'issue' it's that I'm returning an empty view in onCreateView but I don't know how to retain the fragment, return it's view prepopulated with data and manage all web service calling from the main activity.
In case you can't tell, Android is not a primary language for me and this probably looks a shambles. Any help is appreciated I'm getting rather frustrated.
If you're not using any alternative resources when the Activity is re-created, you could try handling the rotation event yourself by using configChange flags in your AndroidManifest:
<activity
...
android:configChanges="orientation|screenSize"
... />
There is no way to keep the same, pre-populated Views if your Activity is re-created since this would cause a Context leak:
http://www.curious-creature.org/2008/12/18/avoid-memory-leaks-on-android/