I have a main fragment with a viewpager inside it. This viewpager has 2 pages (list fragments). When I start the activty, the main fragment is shown and I also show the first paged fragment. This paged fragment displays data from a db using AsyncTask.
In the main fragment I have:
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
onPageSelected(0);
}
#Override
public void onPageSelected(int position) {
Fragment fragment = (Fragment) pagerAdapter.instantiateItem(viewPager, position);
if (fragment instanceof IPagedFragment) {
((IPagedFragment) fragment).onShown(getActivity());
}
}
And the interface is:
public interface IPagedFragment {
void onShown(FragmentActivity activity);
}
The first issue I have is that I have to pass the activity as a parameter because when onShown gets called, the activity is still null.
Furthermore, the paged fragments use progressbar logic similar to the LoginActivity sample. I also get the following exception:
IllegalStateException: Fragment PagedFragment1{4201f758} not attached to Activity
at android.support.v4.app.Fragment.getResources(Fragment.java:620)
So what is the correct stage to start retrieving data from db once the paged fragment is fully available to the UI?
Issues like yours is the reason some developers are starting to question if fragments are really that good or useful.
Also "the correct" is debatable as you can do it in a variety of places and different developers will give you different answers, But let me try to supply you some useful info.
The attach/detach callbacks:
public void onAttach(Activity activity);
public void onDetach();
between those two methods any call to getActivity() will return the non-null activity the fragments is connected to. You can override them and use a private boolean isAttached to keep track of that call.
Also useful is the:
public void onActivityCreated (Bundle savedInstanceState)
this method is called AFTER the Activity.onCreate method. That is very important if you rely on some initialisation that happened there.
Also it's important to remember that on the moment the fragment transaction happens, the Fragment.onCreate happens after the Activity.onCreate and during rotation it happens before it.
As a general rule of thumb I use the Fragment.onStart() / Fragment.onStop() for getting/listening to data. On those calls, all the UI have been created, the fragment is attached to the activity and those callbacks don't get called if there's a dialog/popup (pause/resume does)
From the documentation:
public void onActivityCreated (Bundle savedInstanceState)
[...] tells the fragment when it is fully associated with the new activity instance.
source: http://developer.android.com/reference/android/app/Fragment.html#onActivityCreated(android.os.Bundle)
To get the reference of your activity, create a local object of fragmentActivity and get your activity reference as shown below.
private FragmentActivity fragmentActivity;
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
fragmentActivity=activity;
}
I have Fragment "A" where I have an ImageButton in place. Upon clicking this button a DialogFragment "B" is called to the foreground where Fragment "A" is partially visible in the background. DialogFragment "B" presents the user with a list of choices. Upon clicking a specific choice DialogFragment "B" is dismissed via Dismiss() and Fragment "A" becomes fully visible again.
During this action I need to update the ImageButton on Fragment "A" to represent the user's choice made on DialogFragment "B" (basically a new image for the ImageButton).
Am I correct in thinking the right place to update the ImageButton on Fragment "A" is during OnResume? Does Fragment "A" go into OnPause while FragmentDialog "B" is being shown? Therefore upon returning from DialogFragment "B", Fragment "A" would trigger its OnResume and that's where I should make the update changes to the ImageButton being presented to the user?
I hope my explanation is clear. Any detailed help on where and how I should be updating the ImageButton would be highly appreciated.
With the addition of ViewModels and LiveData solving this problem just got easier. Create a viewModel which both fragments reference. Put the next line in the OnCreate of the fragments. Can also be in onCreateDialog of the dialogfragment.
myViewModel = ViewModelProviders.of(getActivity()).get(MyViewModel.class);
When the dialog is dismissed, call a method on myViewModel, which updates a LiveData variable:
dialogBuilder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialogInterface, int i) {
myViewModel.setButtonPressed(PositiveButtonPressed);
}
});
dialogBuilder.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialogInterface, int i) {
myViewModel.setButtonPressed(NegativeButtonPressed)
}
});
In the viewModel the method sets a MutuableLiveData variable for example to the image to be shown.
void SetButtonPressed(int buttonPressed){
if (buttonPressed==positiveButtonPressed){
imageToBeShown.setValue(image A);
}
else{
imageToBeShown.setValue(image B);
}
}
Set an observer to LiveData variable in onActivityCreated:
myViewModel.imageToBeShown().observe(getViewLifecycleOwner(), new Observer<Image>() {
#Override
public void onChanged(#Nullable Image image) {
button.setBackground(image);
}
}
});
Of course you can implement a getter method and keep the MutuableLiveData variable private. The observer then just obeserves the getter methode.
I had same problem when tried with Interface-Callback method but OnResume of Fragment didn't got triggered when DialogFragment was dismissed since we are not switching to other activity.
So here Event Bus made life easy. Event Bus is the easiest and best way to make communication between activities and fragments with only three step, you can see it here
This is nothing but publish/subscribe event bus mechanism. You will get proper documentation here
Add EventBus dependency to your gradle file -
compile 'org.greenrobot:eventbus:x.x.x'
OR
compile 'org.greenrobot:eventbus:3.1.1' (Specific version)
For the above scenario -
Create one custom POJO class for user events -
public class UserEvent {
public final int userId;
public UserEvent(int userId) {
this.userId = userId;
}
}
Subscribe an event in Fragment A whenever it is posted/published from DialogFragment or from somewhere else -
#Subscribe(threadMode = ThreadMode.MAIN)
public void onUserEvent(UserEvent event) {
// Do something with userId
Toast.makeText(getActivity(), event.userId, Toast.LENGTH_SHORT).show();
}
Register or Unregister your EventBus from your Fragment A's lifecycle especially in onStart and onStop respectively -
#Override
public void onStart() {
super.onStart();
EventBus.getDefault().register(this);
}
#Override
public void onStop() {
EventBus.getDefault().unregister(this);
super.onStop();
}
In the end, on clicking specific item, Publish/Post your event from DialogFragment -
EventBus.getDefault().post(new MessageEvent(user.getId()));
Fragment A won't go into onPause so onResume won't get called
http://developer.android.com/guide/components/fragments.html
Resumed
The fragment is visible in the running activity.
Paused
Another activity is in the foreground and has focus, but the activity
in which this fragment lives is still visible (the foreground activity
is partially transparent or doesn't cover the entire screen).
Here is what I would like to do:
1) Inside an Activity a dialog is shown. I use DialogFragment and FragmentManager for this, by calling:
dialogFragment.show(fragmentManager, "edit_task_list");
2) Inside the Dialog I have layout with a custom Button. I would like to perform some action when the button is clicked and later close the dialog.
How should I connect everything? I see two options:
1) onclick attribute in the Button and a method inside the Actvity. That was my original plan, but I don't how to get the Dialog from the Activity to dismiss it. Even if this is not the right way, how could this be done? I would like to understand how this works.
2) set on click listener on the button when the Dialog is created in DialogFragment. This will require me to pass some context from the Activity to the DialogFragment, so I would like to avoid it (and keep the DialogFragment as simple as possible).
Which of those options should I take?
Number 2 Doesn't require you to pass any context (and you shouldn't). You define an interface that can act as a contract between fragments and activities and make your activity implement it.
From your dialog and in your button.onClick(), you do something like this (untested code):
if ( getActivity() != null
&& !getActivity().finishing()
&& getActivity() instanceOf YourInterface) {
((YourInterface)getActivity()).onSomeNiceMethod();
dismiss(); // close the dialog (if this is what you want).
}
The interface looks like:
public interface YourInterface {
void onSomeNiceMethod();
}
And your Activity…
public class YourActivity implements YourInterface {
void onSomeNiceMethod() {
// Hey! The Button In The Dialog Has Been Pressed!
}
}
All Activity and Fragment classes have a built-in callback method for you to use when you start another Activity, Fragment, Dialog, or DialogFragment.
void onActivityResult(int requestCode, int resultCode, Intent data)
Since you want to start the Dialog from an Activity, using the Dialog class is better than the DialogFragment class. The latter is better for starting a dialog from a Fragment, because it has two methods for communicating back to the Fragment (get/set TargetFragment())
The Dialog class has the getOwnerActivity() method. This is the Activity you use when creating the Dialog with one of its constructors.
You set a onClickListener on the button in the Dialog class. To pass the result back to the Activity:
getOwnerActivity().onActivityResult(intIdentifyingme, Activity.RESULT_OK,
intent);
dismiss(); // close the dialog
You put additional info you want to send in an Intent.
1) onclick attribute in the Button and a method inside the Actvity.
That was my original plan, but I don't how to get the Dialog from the
Activity to dismiss it. Even if this is not the right way, how could
this be done? I would like to understand how this works.
Basically your Activity has to remember/know which dialog is active at the moment with something like curDialog=dialogFragment;, then when handling the button onclick action you'll know which dialog to dismiss. But this is really not a good idea since basically the Button View would "leak" from your DialogFragment to your Activity, which breaks object encapsulation.
2) set on click listener on the button when the Dialog is created in
DialogFragment. This will require me to pass some context from the
Activity to the DialogFragment, so I would like to avoid it (and keep
the DialogFragment as simple as possible).
As a previous answer mentioned, you don't need to pass any Context to it, especially since you can get the Activity by calling getActivity().
The solution depends on whether or not this dialog would be used by multiple Activities:
Used by a single Activity: #Martin's solution will work just fine
Used by multiple Activity: abstraction can be used such that only the user's decision is passed to a listener. This is a (modified) solution I came up for the same problem:
public class BaseDialogFragment extends DialogFragment {
protected TextView dialogEn;
protected Button dialogYes;
private Button dialogNo;
protected OnSelectListener listener;
public interface OnSelectListener {
public void onSelect(int type, boolean yes);
}
public void setOnSelectListener(OnSelectListener listener) {
this.listener = listener;
}
public BaseDialogFragment() {
super();
}
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.dialog_confirm, container, false);
dialogYes = (Button) v.findViewById(R.id.yes);
dialogNo = (Button) v.findViewById(R.id.no);
dialogEn = (TextView) view.findViewById(R.id.dialog_en);
dialogEn.setText(getArguments().getString("text_en"));
dialogYes.setOnClickListener(this);
dialogNo.setOnClickListener(this);
return v;
}
public void onClick(View v) {
if (listener != null) {
listener.onSelect(getArguments().getInt("type"),
v == dialogYes ? true : false);
}
getDialog().dismiss();
}
}
To use it some additional info needs to be provided:
Bundle bundle = new Bundle();
bundle.putInt("type", type); //type: an unique integer value that helps differentiate result from different dialogs
bundle.putString("text_en", en); //en: String to be displayed
dialog.setArguments(bundle);
dialog.setOnSelectListener(this);
So if the type value above is set to 115, then a dialogYes button click would trigger public void onSelect(int type, boolean yes) method to be called with 115 and true as the 1st & 2nd parameters.
Your first point about the onClick attribute in the xml should be avoided. Because handling a Dialog that way could be really painfull if you respect events like screen rotation or a setup with multiple dialogs. This leads into leaked window errors most of the time and needs unnecessary code overhead to avoid this. Because you have to keep track of the Dialog which is actually shown yourself.
To be able to dismiss the Dialog this way you can use the Tag you setted as you called dialogFragment.show(fragmentManager, "edit_task_list");
DialogFragment frag = (DialogFragment)getFragmentManager().findFragmentByTag("edit_task_list");
if(frag != null)
frag.dismiss();
The proper solution is to use an interface as a callback for the communication between the DialogFragment and the Activity. This keeps the Dialog modular and the code easy. Here is an example from the docs. For this you don't need a Context. You simply pass the interface to the dialog in the onAttach() callback. It has a reference of the Activity as a parameter, which called that Dialog.
// Example interface for the communication
public interface OnArticleSelectedListener {
public void onButtonClicked(/*any Parameters*/);
}
public static class FragmentA extends DialogFragment {
OnArticleSelectedListener mListener;
...
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
try {
mListener = (OnArticleSelectedListener) activity; // get the interface of the Activity
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement OnArticleSelectedListener");
}
}
...
}
Handle the Button click in the Dialog and call dismiss() in it, that the Dialog can dismiss itself. Have a look at this question why to use dismiss() instead of getDialog().dismiss().
yourButton.setOnClickListener(new OnClickListener(){
#Override
public void onClick(View v){
if(mListener != null) // check if the listener is still valid
mListener.onButtonClicked(...); // calls the Activity implementation of this callback
dismiss(); // dismiss the Dialog
}
});
In onPause() of the Dialog set the reference of the interface to null. This way you can be sure that the callback will only be used if the Dialog is showing.
Your Activity looks something like this to be able to handle the callback:
public class MyActivity extends Activity implements OnArticleSelectedListener{
...
#Override
public void onButtonClicked(...){
// your implementation here
}
}
I don't know your overall setup but if you would use an AlertDialog a click on the Buttons dismiss the Dialog automatically when the method returns.
I have an activity which may show some DialogFragments. This activity needs to get the response from the dialogs.
I use a listener. In activity:
ProgressMarkDialog dialog = new ProgressMarkDialog();
dialog.setOnProgressMarkSelected(new ProgressMarkDialog.OnProgressMarkSelected() {
#Override
public void onSelect(final int a) {
//some code..
}
});
In the dialog:
public void setOnProgressMarkSelected(OnProgressMarkSelected onProgressMarkSelected) {
this.onProgressMarkSelected = onProgressMarkSelected;
}
This code works fine until somehow the activity is destroyed, but the dialog still open. The program will crash with NullPointerException because the onProgressMarkSelected is null.
I can use
#Override
public void onAttach(final Activity activity) {
super.onAttach(activity);
onProgressMarkSelected = (OnProgressMarkSelected) activity;
}
and implement the interface in the activity.
But if I have few DialogFragments, that means I should implement few interface in the activity and the code will be very messy.
What is the Android best practice for this case?
In my opinion the best way is to stick to the standard positive/negative buttons and attaching DialogInterface.OnClickListener as shown in the http://developer.android.com/reference/android/app/DialogFragment.html
Look at it this way: standard Android user expects to see positive and/or negative button in the dialog. The Activity -if needed- should only be informed about the result (positive, negative input data) of the dialog. Any other input validation should be handled inside the DialogFragment
You could use inheritance with interfaces. Because on interfaces multiple inheritance is possible like this:
public interface A(){
void doA();
}
public interface B(){
void doB();
}
public interface BundleAB extends A, B {
void justAnotherMethod();
}
With this you can bundle your interfaces and use it like this:
public class MyClass implements BundleAB {
#Override
public void doA(){}
#Override
public void doB(){}
#Override
public void justAnotherMethod(){}
}
I am trying to prevent dialogs built with Alert builder from being dismissed when the Activity is restarted.
If I overload the onConfigurationChanged method I can successfully do this and reset the layout to correct orientation but I lose sticky text feature of edittext. So in solving the dialog problem I have created this edittext problem.
If I save the strings from the edittext and reassign them in the onCofiguration change they still seem to default to initial value not what was entered before rotation. Even if I force an invalidate does seem to update them.
I really need to solve either the dialog problem or the edittext problem.
Thanks for the help.
The best way to avoid this problem nowadays is by using a DialogFragment.
Create a new class which extends DialogFragment. Override onCreateDialog and return your old Dialog or an AlertDialog.
Then you can show it with DialogFragment.show(fragmentManager, tag).
Here's an example with a Listener:
public class MyDialogFragment extends DialogFragment {
public interface YesNoListener {
void onYes();
void onNo();
}
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
if (!(activity instanceof YesNoListener)) {
throw new ClassCastException(activity.toString() + " must implement YesNoListener");
}
}
#Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
return new AlertDialog.Builder(getActivity())
.setTitle(R.string.dialog_my_title)
.setMessage(R.string.dialog_my_message)
.setPositiveButton(android.R.string.yes, new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
((YesNoListener) getActivity()).onYes();
}
})
.setNegativeButton(android.R.string.no, new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
((YesNoListener) getActivity()).onNo();
}
})
.create();
}
}
And in the Activity you call:
new MyDialogFragment().show(getSupportFragmentManager(), "tag"); // or getFragmentManager() in API 11+
This answer helps explain these other three questions (and their answers):
Android Best way of avoid Dialogs to dismiss after a device rotation
Android DialogFragment vs Dialog
How can I show a DialogFragment using compatibility package?
// Prevent dialog dismiss when orientation changes
private static void doKeepDialog(Dialog dialog){
WindowManager.LayoutParams lp = new WindowManager.LayoutParams();
lp.copyFrom(dialog.getWindow().getAttributes());
lp.width = WindowManager.LayoutParams.WRAP_CONTENT;
lp.height = WindowManager.LayoutParams.WRAP_CONTENT;
dialog.getWindow().setAttributes(lp);
}
public static void doLogout(final Context context){
final AlertDialog dialog = new AlertDialog.Builder(context)
.setIcon(android.R.drawable.ic_dialog_alert)
.setTitle(R.string.titlelogout)
.setMessage(R.string.logoutconfirm)
.setPositiveButton("Yes", new DialogInterface.OnClickListener()
{
#Override
public void onClick(DialogInterface dialog, int which) {
...
}
})
.setNegativeButton("No", null)
.show();
doKeepDialog(dialog);
}
If you're changing the layout on orientation change I wouldn't put android:configChanges="orientation" in your manifest because you're recreating the views anyway.
Save the current state of your activity (like text entered, shown dialog, data displayed etc.) using these methods:
#Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
}
#Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
}
That way the activity goes through onCreate again and afterwards calls the onRestoreInstanceState method where you can set your EditText value again.
If you want to store more complex Objects you can use
#Override
public Object onRetainNonConfigurationInstance() {
}
Here you can store any object and in onCreate you just have to call getLastNonConfigurationInstance(); to get the Object.
Just add android:configChanges="orientation" with your activity
element in AndroidManifest.xml
Example:
<activity
android:name=".YourActivity"
android:configChanges="orientation"
android:label="#string/app_name"></activity>
A very easy approach is to create the dialogs from the method onCreateDialog() (see note below). You show them through showDialog(). This way, Android handles the rotation for you and you do not have to call dismiss() in onPause() to avoid a WindowLeak and then you neither have to restore the dialog. From the docs:
Show a dialog managed by this activity. A call to onCreateDialog(int, Bundle) will be made with the same id the first time this is called for a given id. From thereafter, the dialog will be automatically saved and restored.
See Android docs showDialog() for more info. Hope it helps somebody!
Note: If using AlertDialog.Builder, do not call show() from onCreateDialog(), call create() instead. If using ProgressDialog, just create the object, set the parameters you need and return it. In conclusion, show() inside onCreateDialog() causes problems, just create de Dialog instance and return it. This should work! (I have experienced issues using showDialog() from onCreate() -actually not showing the dialog-, but if you use it in onResume() or in a listener callback it works well).
This question was answered a long time ago.
Yet this is non-hacky and simple solution I use for myself.
I did this helper class for myself, so you can use it in your application too.
Usage is:
PersistentDialogFragment.newInstance(
getBaseContext(),
RC_REQUEST_CODE,
R.string.message_text,
R.string.positive_btn_text,
R.string.negative_btn_text)
.show(getSupportFragmentManager(), PersistentDialogFragment.TAG);
Or
PersistentDialogFragment.newInstance(
getBaseContext(),
RC_EXPLAIN_LOCATION,
"Dialog title",
"Dialog Message",
"Positive Button",
"Negative Button",
false)
.show(getSupportFragmentManager(), PersistentDialogFragment.TAG);
public class ExampleActivity extends Activity implements PersistentDialogListener{
#Override
void onDialogPositiveClicked(int requestCode) {
switch(requestCode) {
case RC_REQUEST_CODE:
break;
}
}
#Override
void onDialogNegativeClicked(int requestCode) {
switch(requestCode) {
case RC_REQUEST_CODE:
break;
}
}
}
Definitely, the best approach is by using DialogFragment.
Here is mine solution of wrapper class that helps to prevent different dialogs from being dismissed within one Fragment (or Activity with small refactoring). Also, it helps to avoid massive code refactoring if for some reasons there are a lot of AlertDialogs scattered among the code with slight differences between them in terms of actions, appearance or something else.
public class DialogWrapper extends DialogFragment {
private static final String ARG_DIALOG_ID = "ARG_DIALOG_ID";
private int mDialogId;
/**
* Display dialog fragment.
* #param invoker The fragment which will serve as {#link AlertDialog} alert dialog provider
* #param dialogId The ID of dialog that should be shown
*/
public static <T extends Fragment & DialogProvider> void show(T invoker, int dialogId) {
Bundle args = new Bundle();
args.putInt(ARG_DIALOG_ID, dialogId);
DialogWrapper dialogWrapper = new DialogWrapper();
dialogWrapper.setArguments(args);
dialogWrapper.setTargetFragment(invoker, 0);
dialogWrapper.show(invoker.getActivity().getSupportFragmentManager(), null);
}
#Override
public void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mDialogId = getArguments().getInt(ARG_DIALOG_ID);
}
#NonNull
#Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
return getDialogProvider().getDialog(mDialogId);
}
private DialogProvider getDialogProvider() {
return (DialogProvider) getTargetFragment();
}
public interface DialogProvider {
Dialog getDialog(int dialogId);
}
}
When it comes to Activity you can invoke getContext() inside onCreateDialog(), cast it to the DialogProvider interface and request a specific dialog by mDialogId. All logic to dealing with a target fragment should be deleted.
Usage from fragment:
public class MainFragment extends Fragment implements DialogWrapper.DialogProvider {
private static final int ID_CONFIRMATION_DIALOG = 0;
#Override
public void onViewCreated(View view, #Nullable Bundle savedInstanceState) {
Button btnHello = (Button) view.findViewById(R.id.btnConfirm);
btnHello.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
DialogWrapper.show(MainFragment.this, ID_CONFIRMATION_DIALOG);
}
});
}
#Override
public Dialog getDialog(int dialogId) {
switch (dialogId) {
case ID_CONFIRMATION_DIALOG:
return createConfirmationDialog(); //Your AlertDialog
default:
throw new IllegalArgumentException("Unknown dialog id: " + dialogId);
}
}
}
You can read the complete article on my blog How to prevent Dialog being dismissed? and play with the source code.
It seems that this is still an issue, even when "doing everything right" and using DialogFragment etc.
There is a thread on Google Issue Tracker which claims that it is due to an old dismiss message being left in the message queue. The provided workaround is quite simple:
#Override
public void onDestroyView() {
/* Bugfix: https://issuetracker.google.com/issues/36929400 */
if (getDialog() != null && getRetainInstance())
getDialog().setDismissMessage(null);
super.onDestroyView();
}
Incredible that this is still needed 7 years after that issue was first reported.
You can combine the Dialog's onSave/onRestore methods with the Activity's onSave/onRestore methods to keep the state of the Dialog.
Note: This method works for those "simple" Dialogs, such as displaying an alert message. It won't reproduce the contents of a WebView embedded in a Dialog. If you really want to prevent a complex dialog from dismissal during rotation, try Chung IW's method.
#Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
myDialog.onRestoreInstanceState(savedInstanceState.getBundle("DIALOG"));
// Put your codes to retrieve the EditText contents and
// assign them to the EditText here.
}
#Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
// Put your codes to save the EditText contents and put them
// to the outState Bundle here.
outState.putBundle("DIALOG", myDialog.onSaveInstanceState());
}
I had a similar problem: when the screen orientation changed, the dialog's onDismiss listener was called even though the user didn't dismiss the dialog. I was able to work around this by instead using the onCancel listener, which triggered both when the user pressed the back button and when the user touched outside of the dialog.
In case nothing helps, and you need a solution that works, you can go on the safe side, and each time you open a dialog save its basic info to the activity ViewModel (and remove it from this list when you dismiss dialog). This basic info could be dialog type and some id (the information you need in order to open this dialog). This ViewModel is not destroyed during changes of Activity lifecycle. Let's say user opens a dialog to leave a reference to a restaurant. So dialog type would be LeaveReferenceDialog and the id would be the restaurant id. When opening this dialog, you save this information in an Object that you can call DialogInfo, and add this object to the ViewModel of the Activity. This information will allow you to reopen the dialog when the activity onResume() is being called:
// On resume in Activity
override fun onResume() {
super.onResume()
// Restore dialogs that were open before activity went to background
restoreDialogs()
}
Which calls:
fun restoreDialogs() {
mainActivityViewModel.setIsRestoringDialogs(true) // lock list in view model
for (dialogInfo in mainActivityViewModel.openDialogs)
openDialog(dialogInfo)
mainActivityViewModel.setIsRestoringDialogs(false) // open lock
}
When IsRestoringDialogs in ViewModel is set to true, dialog info will not be added to the list in view model, and it's important because we're now restoring dialogs which are already in that list. Otherwise, changing the list while using it would cause an exception. So:
// Create new dialog
override fun openLeaveReferenceDialog(restaurantId: String) {
var dialog = LeaveReferenceDialog()
// Add id to dialog in bundle
val bundle = Bundle()
bundle.putString(Constants.RESTAURANT_ID, restaurantId)
dialog.arguments = bundle
dialog.show(supportFragmentManager, "")
// Add dialog info to list of open dialogs
addOpenDialogInfo(DialogInfo(LEAVE_REFERENCE_DIALOG, restaurantId))
}
Then remove dialog info when dismissing it:
// Dismiss dialog
override fun dismissLeaveReferenceDialog(Dialog dialog, id: String) {
if (dialog?.isAdded()){
dialog.dismiss()
mainActivityViewModel.removeOpenDialog(LEAVE_REFERENCE_DIALOG, id)
}
}
And in the ViewModel of the Activity:
fun addOpenDialogInfo(dialogInfo: DialogInfo){
if (!isRestoringDialogs){
val dialogWasInList = removeOpenDialog(dialogInfo.type, dialogInfo.id)
openDialogs.add(dialogInfo)
}
}
fun removeOpenDialog(type: Int, id: String) {
if (!isRestoringDialogs)
for (dialogInfo in openDialogs)
if (dialogInfo.type == type && dialogInfo.id == id)
openDialogs.remove(dialogInfo)
}
You actually reopen all the dialogs that were open before, in the same order. But how do they retain their information? Each dialog has a ViewModel of its own, which is also not destroyed during the activity lifecycle. So when you open the dialog, you get the ViewModel and init the UI using this ViewModel of the dialog as always.
Yes, I agree with the solution of using DialogFragment given by #Brais Gabin, just want to suggest some changes to the solution given by him.
While defining our custom class that extends DialogFragment, we require some interfaces to manage the actions ultimately by the activity or the fragment that has invoked the dialog. But setting these listener interfaces in the onAttach(Context context) method may sometimes cause ClassCastException that may crash the app.
So to avoid this exception, we can create a method to set the listener interfaces and call just it after creating the object of the dialog fragment.
Here is a sample code that could help you understand more-
AlertRetryDialog.class
public class AlertRetryDialog extends DialogFragment {
public interface Listener{
void onRetry();
}
Listener listener;
public void setListener(Listener listener)
{
this.listener=listener;
}
#NonNull
#Override
public Dialog onCreateDialog(#Nullable Bundle savedInstanceState) {
AlertDialog.Builder builder=new AlertDialog.Builder(getActivity());
builder.setMessage("Please Check Your Network Connection").setPositiveButton("Retry", new
DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
//Screen rotation will cause the listener to be null
//Always do a null check of your interface listener before calling its method
if(listener!=null&&listener instanceof HomeFragment)
listener.onRetry();
}
}).setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
}
});
return builder.create();
}
}
And in the Activity or in the Fragment you call-
AlertRetryDialog alertRetryDialog = new AlertRetryDialog();
alertRetryDialog.setListener(HomeFragment.this);
alertRetryDialog.show(getFragmentManager(), "tag");
And implement the methods of your listener interface in your Activity or the Fragment-
public class YourActivity or YourFragment implements AlertRetryDialog.Listener{
//here's my listener interface's method
#Override
public void onRetry()
{
//your code for action
}
}
Always make sure that you do a null check of the listener interfaces before calling any of its methods to prevent NullPointerException (Screen rotation will cause the listener interfaces to be null).
Please do let me know if you find this answer helpful. Thank You.
Just use
ConfigurationChanges = Android.Content.PM.ConfigChanges.Orientation | Android.Content.PM.ConfigChanges.ScreenSize
and app will know how to handle rotation and screen size.