I have searched the numerous questions that look like this one, but haven't found my answer in any of them.
I have an activity that has 3 tabs accessible through the action bar. I achieved this by adding 3 fragments that inflate a custom view I made extending the view class.
At the moment the database changes, I try to refresh the view in my tab by calling invalidate()/postinvalidate(), but this does not work. The same is true for calling onCreateView of the fragment just as many other options I considered.
When I go to another tab and go back, however, the change has been made and my view is updated as it should be.
How can I simulate the same thing that happens when changing to another tab? What does happen. I tried to look at the Fragment lifecycle (tried to call onCreateView()) to figure it out but it just doesn't want to refresh/redraw as it should.
The data is loaded properly, as the data is changed when I change to another tab.
I deleted some of the code as it is no longer relevant. I implemented Cursorloaders instead of my own Observer pattern to notify a change. This is my main activity right now.
The question is what should I do now if I want to redraw the view inside these fragments. If I apply fragmentObject.getView().invalidate() it does not work. I'm having the same problem as before, but now my Observer to notify a change in the database is properly implemented with loaders.
public class ArchitectureActivity extends Activity implements LoaderManager.LoaderCallbacks<Cursor> {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
ActionBar actionbar = getActionBar();
actionbar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
ActionBar.Tab EditTab = actionbar.newTab().setText("Edit");
ActionBar.Tab VisualizeTab = actionbar.newTab().setText("Visualize");
ActionBar.Tab AnalyseTab = actionbar.newTab().setText("Analyse");
Fragment editFragment = new EditFragment();
Fragment visualizeFragment = new VisualizeFragment();
Fragment analyseFragment = new AnalyseFragment();
EditTab.setTabListener(new MyTabsListener(editFragment));
VisualizeTab.setTabListener(new MyTabsListener(visualizeFragment));
AnalyseTab.setTabListener(new MyTabsListener(analyseFragment));
actionbar.addTab(EditTab);
actionbar.addTab(VisualizeTab);
actionbar.addTab(AnalyseTab);
ArchitectureApplication architectureApplication = (ArchitectureApplication)getApplicationContext();
architectureApplication.initialize();
getLoaderManager().initLoader(0, null, this);
getLoaderManager().initLoader(1, null, this);
}
public Loader<Cursor> onCreateLoader(int id, Bundle args) {
if (id == 0){
return new CursorLoader(this, GraphProvider.NODE_URI , null, null, null, null);
} else if (id == 1){
return new CursorLoader(this, GraphProvider.ARC_URI , null, null, null, null);
}
return null;
}
public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) {
// Reloading of data, actually happens because when switching to another tab the new data shows up fine
Log.e("Data", "loaded");
}
public void onLoaderReset(Loader<Cursor> loader) {
}
}
Don't try to call onCreateView() yourself... it's a lifecycle method and should be called only by the framework.
Fragments are re-usable UI components. They have their own lifecycle, display their own view, and define their own behavior. You usually don't need to have your Activity mess around with the internal workings of a Fragment, as the Fragment's behavior should be self-contained and independent of any particular Activity.
That said, I think the best solution is to have each of your Fragments implement the LoaderManager.LoaderCallbacks<D> interface. Each Fragment will initialize a Loader (i.e. a CursorLoader if you are using a ContentProvider backed by an SQLite database), and that Loader will be in charge of (1) loading the data on a background thread, and (2) listening for content changes that are made to the data source, and delivering new data to onLoadFinished() whenever a content change occurs.
This solution is better than your current solution because it is entirely event-driven. You only need to refresh the view when data is delivered to onLoadFinished() (as opposed to having to manually check to see if the data source has been changed each time you click on a new tab).
If you are lazy and just want a quick solution, you might be able to get away with refreshing the view in your Fragment's onResume() method too.
I had a similar (although not identical) problem that I could solve in the following way:
In the fragment I added
public void invalidate() {
myView.post(new Runnable() {
#Override
public void run() {
myView.invalidate();
}
});
}
and I called this method from the activity when I wanted to refresh the view myView of the fragment. The use of post() ensures that the view is only invalidated when it is ready to be drawn.
I've found a workaround to refresh the view inside my fragment. I recreated (new CustomView) the view every time the database has been updated. After that I call setContentView(CustomView view). It looks more like a hack, but it works and nothing else that I tried does.
Although my problem was not actually solved, I gave the reward to Alex Lockwood. His advice on Loaders made my application better and it caused me to keep looking for a solution that I eventually found.
I had the same issue.
My solution was detach fragment and attach it again.
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
Fragment f = getFragment(action);
if(forceUpdate)
{
fragmentTransaction.detach(f);
fragmentTransaction.attach(f);
}
fragmentTransaction.replace(R.id.mainFragment, f);
fragmentTransaction.commit();
currentAction = action;
The fastest solution working for me:
#Override
public void onPause() {
super.onPause();
if (isRemoving() && fragmentView != null) {
((ViewGroup) fragmentView).removeAllViews();
}
}
Related
I'm new to SO and fairly new to coding, so please accept my apologies in advance if I break rules or expectations here.
I have an unusual setup involving two recyclerViews, which I'll explain here and also paste a simplified version of the code below (as there is so much not relevant to this question).
In what I'll call verticalRecyclerViewActivity, a verticalRecyclerViewAdapter is called, with data it fetches from Firebase and loads into arrayLists.
If the user clicks on an item in the vertical recyclerview, a new dialog fragment which I'll call horizontalRecyclerViewDialogFragment is inflated, and that loads what I'll call horizontalRecyclerView (which has similar items to the vertical one, in more detail, with options to click on them to review them).
If the user clicks on an item in the horizontalRecyclerView, a new activity which I'll call reviewItem is started (through an Intent). When the user submits their review, it finishes and returns (through the backstack) to the horizontal RecyclerView. That can also happen if they press the back button without actually submitting a review. That all works fine, but I need the horizontalRecyclerView to show that they have (or haven't) reviewed the item and state the score they gave it in a review.
Calling notifyDataSetChanged won't work for this because of how information comes through two recyclerViews and Firebase calls (or, at least, it would be very inefficient).
I've tried using startActivityForResult (I know it's deprecated, but if I could get that to work I could try using the newer equivalent which I don't yet understand) but the problem is that the result is returned to the original (VerticalRecylcerView) activity, which is two recyclerView adapters and one fragment beneath what needs to be updated, and I don't know how to pass that data to the horizontal Recyclerview.
I've also tried using interfaces but was unable to pass it through the Intent (tried using Parcelable and Serializable, but it seems neither can work in this situation?).
Since the review is updated on Firebase, I could have the horizontal Recyclerview listen for a change, but that seems very inefficient?
So I've found a solution using localBroadcast (which I know is also deprecated). The Intent (with the review score) is transmitted when it is reviewed and received in the horizontal recyclerView adapter. But when and how should I unregister the adapter? Ideally the receiver would be turned on when the user goes to the Review activity and turned off once the user returns from that activity and the (horizontal) recyclerView holder is updated, whether the review is successfully submitted or whether the user just presses the back button and never submits a review.
My question is similar to this one: How to unregister and register BroadcastReceiver from another class?
That is noted as a duplicate of this one: How to unregister and register BroadcastReceiver from another class?
There's a lot in those questions I don't understand, but the important difference I think between their and my cases is that I would just like the receiver to know when a review is submitted, and ideally be unregistered then, or possibly when the viewHolder is recycled, which I tried but also didn't work since it's not connected to the viewHolder (should it be?).
Any help would be much appreciated, thank you!
public class verticalRecyclerViewActivity extends AppCompatActivity {
// Loads an XML file and assembles an array from Firebase.
mVerticalRecyclerView = findViewById(R.id.verticalRecyclerView);
verticalRecyclerViewAdaptor mVerticalRecyclerViewAdaptor = new verticalRecyclerViewAdaptor (this); // also pass other information it needs
mVerticalRecyclerView .setAdapter(mVerticalRecyclerViewAdaptor);
}
public class verticalRecyclerViewAdaptor extends RecyclerView.Adapter<verticalRecyclerViewAdaptor.singleHolder> {
// Usual recyclerView content
holder.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
horizontalRecyclerViewFragment mHorizontalRecyclerViewFragment = new horizontalRecyclerViewFragment();
// lots of arguments passed it needs.
FragmentManager fragmentManager = ((FragmentActivity) view.getContext()).getSupportFragmentManager();
mHorizontalRecyclerViewFragment.show(fragmentManager, null);
}
public class mHorizontalRecyclerViewFragment extends DialogFragment {
public Dialog onCreateDialog(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mContext = getActivity().getApplicationContext(); // Not sure why I need this, but it works.
View horizontalRecyclerViewView = getActivity().getLayoutInflater().inflate(R.layout.horizontal_recyclerview_holder, new CardView(getActivity()), false);
Dialog horizontalRecyclerViewDialog = new Dialog(getActivity());
horizontalRecyclerViewDialog.setContentView(horizontalRecyclerViewView);
mHorizontalRecyclerView = horizontalRecyclerViewView.getRootView().findViewById(R.id.horizontalRecyclerView);
mHorizontalRecyclerViewAdapter = new horizontalRecyclerViewAdapter (mContext)
// Other arguments passed
mHorizontalRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity(),
LinearLayoutManager.HORIZONTAL, false));
mHorizontalRecyclerView.setAdapter(mHorizontalRecyclerViewAdapter);
}
public class horizontalRecyclerViewAdapter extends RecyclerView.Adapter<horizontalRecyclerViewAdapter.horizontalRecyclerViewHolder> {
public horizontalRecyclerViewAdapter(){}
// Blank constructor and also one with lots of arguments for it to work.
public horizontalRecyclerViewAdapter.horizontalRecyclerViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.horizontal_recyclerview_adaptor_holder, parent, false);
return new horizontalRecyclerViewAdapter.horizontalRecyclerViewHolder(view);
}
public void onBindViewHolder(#NonNull horizontalRecyclerViewHolder holder, int position) {
// Connect up various views.
holder.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
LocalBroadcastManager.getInstance(mContext).registerReceiver(reviewSubmittedListener, new IntentFilter("reviewSubmitted"));
Intent reviewNow = new Intent(view.getContext(), ReviewActivity.class);
// Put extra details with the intent
view.getContext().startActivity(reviewNow);
}
BroadcastReceiver reviewSubmittedListener = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent reviewFinishedIntent) {
int reviewScore = reviewFinishedIntent.getExtras().getInt("reviewScore");
// Update the horizontal RecyclerView with the information received from the review Activity.
}
};
}
public class ReviewActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_review_item);
// Set up the review, using Firebase and data passed through the intent.
}
public void submitReview() {
// Check that the review is complete/valid and submit it through Firebase
LocalBroadcastManager localBroadcastManager = LocalBroadcastManager.getInstance(ReviewItemActivity.this);
Intent reviewFinishedIntent = new Intent("reviewSubmitted");
reviewFinishedIntent.putExtra("reviewScore", overallScore);
LocalBroadcastManager.getInstance(this).sendBroadcast(reviewFinishedIntent);
finish();
}
If you are using RxJava you can use the RxBus else you can use one of many EventBus implementation for this.
If that is not the path you want to take then you can have a shared view model object that can be used only for communication between fragments see this article.
It is surprisingly difficult to get the current fragment when using either of the pager adapters. With the FragmentPagerAdapter, however, you can look for a fragment with the tag "android:switcher:" + viewId + ":" + id.
Unfortunately, there does not seem to be a standard tag for the FragmentStatePagerAdapter. A related question provided a couple answers which suggested manually keeping a cache of the fragments, which were noted as being inadequate when doing a rotation: the underlying adapter stores state in a bundle and restores it when it is created, causing any simple caching solution to fail.
I found a better solution. getCurrentFragment() cannot be implemented correctly from what I can tell.
My code was previously launching a dialog and then calling back to the Activity which was stored by the dialog at onAttach. The Activity then needed to find the correct Fragment, which was problematic.
The correct solution is to first call setTargetFragment() on the new dialog fragment:
SelectProblemDialogFragment f = SelectProblemDialogFragment.newInstance(args);
f.setTargetFragment(this, 0);
f.show(getFragmentManager(), "select_problem_dialog_fragment");
and then in onAttach(), simply use that as the listener.
#Override
public void onAttach(Activity activity)
{
super.onAttach(activity);
try
{
mListener = (SelectProblemDialogListener) getTargetFragment();
if (mListener == null)
{
mListener = (SelectProblemDialogListener) activity;
}
} catch (ClassCastException e)
{
throw new ClassCastException("Must implement SelectProblemDialogListener");
}
}
SITUATION:
An application with resources for portait and landscape, has a simulator that I keep after configuration changes (the user can switch orientation while the simulation is running).
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Installer.installApkData(this);
simulator = new Simulator(this);
MainActivity prevActivity = (MainActivity)getLastCustomNonConfigurationInstance();
if(prevActivity!= null) {
// So the orientation did change
// Restore some field for example
this.simulator = prevActivity.simulator;
//this.mNavigationDrawerFragment = prevActivity.mNavigationDrawerFragment;
//this.mTitle = prevActivity.mTitle;
Log.d("APP","Activity restarted: simulator recreated");
}
requestWindowFeature(Window.FEATURE_PROGRESS);
setContentView(R.layout.activity_main);
setProgressBarVisibility(true);
mNavigationDrawerFragment = (NavigationDrawerFragment) getSupportFragmentManager()
.findFragmentById(R.id.navigation_drawer);
mTitle = getTitle();
// Set up the drawer.
mNavigationDrawerFragment.setUp(R.id.navigation_drawer,
(DrawerLayout) findViewById(R.id.drawer_layout));
}
#Override
public Object onRetainCustomNonConfigurationInstance() {
//restore all your data here
return this;
}
...
There is a method in the activity that changes the selected section in the NavigationDrawer, in the UI thread because if not it crashes.
public void showHud() {
// TODO Auto-generated method stub
runOnUiThread( new Runnable() {
public void run() {
mNavigationDrawerFragment.select(1);
onSectionAttached(2);
restoreActionBar();
}
});
}
This method is used to go directly to display the simulation once the simulator has been connected.
PROBLEM:
All this system works except for when I connect the simulator after switching the orientation. It executes the runOnUiThread but it does nothing. I think the reason for that is that it loses the UI thread that created that view when the activity is restarted.
As you can see there are two lines commented in the reloading of the simulator where I also tried to save the NavigationDrawer object without success in the test: same behavior.
I also tried to save the prevActivity and in the method showHUD(), first asking if its null and if not, execute the method inside the prevActivity. Expecting that it will access the original UI Thread, but I was mistaken.
Is there any solution to keep this UI Thread during the restarting of an activity? or maybe another type of solution?
Thanks a lot.
You should be checking your onSavedInstanceState in your Activity. This is how the Android OS is designed to handle this. You are trying to do this yourself, when you should be relying on the OS supplied functionality.
Quite a few examples of this (if you search SO):
Android: Efficient Screen Rotation Handling
Handle screen rotation without losing data - Android
If you want to save configuration, you need to save specific things. You can do this in the onPause() or on onSaveInstanceState().
If onCreate() is called after your configuration change, you can get what you need back out of the bundle. when you get it back out, you can then set what you need.
See this: http://developer.android.com/training/basics/activity-lifecycle/recreating.html
I am correctly retaining the data object but after a device rotation the function in UI thread has no effect, a function to change the selected section in the NavigationDrawer. I thought it was because I was losing the correct UI thread but actually, what I was losing is this NavigationDrawerFragment.
Just by adding the setRetainInstance(true) line in the OnCreate() of the NavigationDrawerFragment solves the problem:
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setRetainInstance(true);
...
Im new to android dev and Im currently struggling with this annoying problem for days.
Tried google and many articles. None helped. Also tried IRC for some on line help but couldnt get a straight answer. Maybe you can direct me in the right direction...
My app is basically a ViewPager that holds a single Fragment class. Inside the Fragment class, there is a switch case block that determines based on position, which image to load from the resources folder. The thing is, I have a TextView View in my parent Activity that needs to get updated according to the current picture. Like an image title.
I used:
TextView tv = (TextView) getActivity().findViewById(R.id.titleTV);
in onCreateView() to get access to that TextView from within the Fragment. And added a:
tv.setText("Picture 1");
for instance, to the switch case block. This way, when a picture is shown, the text view gets updated.
The problem is, the method that retrieves a new Fragment with each slide, getItem(int position) in the parent Activity, gets called twice to load more than one Fragment to memory. This causes the current position to be one int ahead. Meaning, the switch case stands on case 0 for instance and it shows a specific picture, but the text gets updated from case 1.
I cant get it to work properly because of that.
What am I doing wrong??
Thank you
If you are able to determine text based on current fragment position only you can use ViewPager.OnPageChangeListener. In you Activity implement that interface and use it by calling mViewPager.setOnPageChangeListener(SomeOnPageChangeListener). Determine what text put into TextView with OnPageChangeListener.onPageSelected() method.
Unfortunately there is a bug in SDK and onPageSelected() is not called for page at position 0 when it is shown for the first time. You can find workaround under above link, use ViewPager.setCurrentPage(1) or just set text for that position manually in onCreate() method.
Example code:
//activity onCreate()
protected void onCreate(Bundle savedInstanceState) {
...
mTextView = (TextView) findViewById(R.id.text_view);
mViewPager = (ViewPager) findViewById(R.id.pager);
mViewPager.setAdapter(mPagerAdapter);
mViewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
#Override
public void onPageSelected(int position) {
String someText = determineText(position)
mTextView.setText(someText);
});
//because onPageSelected will not be called for page 0 first time
String someText = determineText(0)
mTextView.setText(someText);
}
private String determineText(int position){ //static?
//switch?
}
Ok I'll give a piece of code, you can use that, not just for a String but for any data at all that you want to send to the Activity from the Fragment, or even from other type of classes between each other.
That's the type of code is also used on .'setOnSomethingHappenListener(listener);'
public interface TitleChangeListener{
public void onTitleChanged(String title);
}
then on your activity you will
public class MyActivity extends Activity implements TitleChangeListener{
#Override
onTitleChanged(String title){
// set here your value
}
}
then on your fragment
public void MyFragment extends Fragment{
private TitleChangeListener listener;
#Override
public void onAttach(Activity activity){
if(activity instanceof TitleChangeListener)
listener = (TitleChangeListener)activity;
else
// throw some error ???
}
#Override
public void onResume(){
listener.onTitleChanged("my title");
}
}
and remember I typed all of that by heart, there is bound to have some small mistakes.
But just follow the idea and you'll be fine.
I'm trying to get the handle on all the new ActionBar and Fragments API.
I have an main activity, and I want it to manage two different tabs.
I'm using the ActionBarSherlock in order to support older version than ICS.
Each tab contains its own Fragment (each one is a subclass of SherlockListFragment)
I got it to work basically nice, but I have a problem that I'm sure that is stupid, but I can't figure it out yet:
On the first time each Fragment is shown, everything is OK, the list is populated and so the MenuItems in the ActionBar.
But the second time you see a tab (After swicth and switch-back), Neither the list get populated, nor the ActionBar MenuItems.
This is how I'm switching the tabs:
#Override
public void onTabSelected(Tab tab, FragmentTransaction transaction) {
SherlockListFragment toAttach = // Find the right fragment here...
if (toAttach != null) {
if (toAttach.isAdded() == false) {
transaction.add(R.id.tab_placeholder, toAttach,
REMINDER_FRAGMENT_TAG);
} else {
transaction.attach(toAttach);
}
}
}
And onTabUneselect I'm detaching the Fragment:
#Override
public void onTabUnselected(Tab tab, FragmentTransaction transaction) {
SherlockListFragment toDetach = // Find the right fragment
if (toDetach != null) {
transaction.detach(toDetach);
}
}
I'm populating the lists and the ActionBar menu in onResume:
#Override
public void onResume() {
super.onResume();
setHasOptionsMenu(true);
fillRemindersList();
}
I also tried it in onStart and onCreateView but it didn't help...
So what am I missing here?
And if there are others issues in my code that I'm unaware of, please do tell.
Thanks!
EDIT:
I just confirmed that onResume dosen't get called after I switch tabs, which is definetly wrong since I'm detaching and re-attaching them...
Am I switching tabs the wrong way?
Try using transaction.remove(fragment) in onTabUnselected and transaction.replace in onTabSelected.
Doing the beginTransaction() and commit() outside of this code I assume or did you forget?
You can see a trick used here from the samples as well:
https://github.com/JakeWharton/ActionBarSherlock/blob/master/samples/fragments/src/com/actionbarsherlock/sample/fragments/FragmentTabs.java