Flow Image I am facing a strange issue related to saving the state in Android.
When I turn on Don't Keep Activities option in Android(From Developer Option). Then if I launch Activity B(which launches Fragment B) from Fragment A (launched by Activity A). Then my onSavedInstance method is getting called in Fragment A but in OnCreate method of Fragment A, I am getting received bundle as null.
And above is inconsistent means sometimes (Specially reproduced when clear the data Android).
In my Activity A in method onSaveInstanceState I have saved my Fragment A with below impl -:
getSupportFragmentManager().putFragment(Bundle,FRAGMENT_TAG,instanceOFFragA);
Also in my onCreate I am trying to retrieve the saved Fragment A with below impl -:
if (savedInstanceState != null) {
args = savedInstanceState;
Fragment fragment = getSupportFragmentManager().getFragment(savedInstanceState, FRAGMENT_TAG);
if (fragment != null && fragment.getClass().equals(FragA.class)) {
instanceOfFragA = (FragA) getSupportFragmentManager().getFragment(savedInstanceState, FRAGMENT_TAG);
}
}
But in OnCreate I am getting instance of Fragment C (which is basically a Registration Fragment which have Login & Register button, Login click will launch LoginActivity which inturn launches LoginFragment. If login get success it calls back on Activity A which launches Fragment A(as login is success)).
I have this scenario in my app:
One activity(A) with multiple fragments calling another activity(B) at some point.
Flow for that goes like this: F1 => F2 => F3 => B or F1 => F2 => B where F(n) represents fragment.After I finish activity B it returns me to F3 or F2 but my goal is to show user F1 so I tried sending event via event bus and replacing any other fragment with F1,note that I'm adding every fragment to backstack.So I succeed with it but if I call fragment F2 or F3 application crashes also sometimes I get "IllegalStateException: Can not perform this action after onSaveInstanceState".
So after trying a lot of approaches I simply did this :
public void onClick(View v){
//started activity B
//replaced current fragment with F1
}
The end result of this was seeing F1 before activity B ,and everything else worked fine without crashing.So to solve that glitch I replaced fragment 100 ms after activity B is started.
public void onClick(View v){
//started activity B
new Handler().(new Runable(){
#Override
public void run()
{
//replaced current fragment with F1
}
},100);
}
But I feel this is ugly way to solve this problem and I want to ask you if there is better solution?
EDIT:
I was inspired by spcial answer so I did similar thing with states.
In activity A I have two variables.
boolean wasAnotherActivityCalled=false;
String showFragment=null;
In my fragment I have this :
public void onClick(View v){
//started activity B
getActivity().wasAnotherActivityCalled=true;
getActivity().showFragment=FragmentOne.class.getSimpleName();
}
in activity A I have this :
#Override
protected void onResumeFragments() {
super.onResumeFragments();
if(wasAnotherActivityCalled)
{
if(showFragment.equals(F1.class.getSimpleName()))
{ //do your logic here}
wasAnotherActivityCalled=false;
showFragment=null;
}
}
I have something similiar in my App. What I did was to use a simple "state-machine" where I have an int attribute which represents the current state (0 = Fragment1, 1 = Fragment2...etc) and an ArrayList with all fragments which I need. If I have to switch the fragment I also increment the state and just load the fragment from the ArrayList.
In my onPause() method I save the state in sharedPreferences() and in the onResume() method I load the state from sharedPreferences() and do a initFragment(state) where I just replace the fragmentLayout with the fragment from fragmentArray[state] :-)
With this behaviour I could handle backstack on my own, can go back and furth and save the state of the current needed fragment everytime the user changes the activity and comes back. Furthermore I don't commit the fragments into backstack because it is already handled through myself.
I hope I could help you with this.
Dont add your fragment into backstack while commiting it
I'm facing a strange problem inside my app. From a fragment, if i push a button, i start new FragmentActivity that contains a fragment and some other elements, but if i would go back to previous Activity (that contain fragment that start the current activity), i need to push back button twice.
First time fragmentActivity seem close itself, but it reopens again. I close FragmentActivity as always:
#Override
public void onBackPressed() {
super.onBackPressed();
finish();
}
so what's wrong?
i start new FragmentActivity that contains a fragment and some other elements
You're most likely adding that FragmentTransaction to the backstack, which is why it's consuming the back button press. You shouldn't need to override onBackPressed() at all. Instead, look at the code where you add the Fragment to the new FragmentActivity and ensure you're not calling .addToBackStack() on the initial transaction. For example, typically in onCreate() you would do something like this:
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.your_container_id, new YourInitialFragment())
.commit();
}
}
I have a two class named Stock Details extends Fragment and another one is Stock info extends activity,
when I was trying to go back to my Stock details pages from Stock info pages it shows "Unfortunately,Application has stopped",but in my program I use
Intent intent = new Intent(this,StockDetails.class);
startActivity(intent);
finish();
for go back to fragment. but it does not work. help me to solve this problem
I am the beginner for android.
kindly help me to go back from an Activity to fragment
you do not need to start activity for StoreDetail as it is a subclass of Fragment not Activity.This is the reason that your app is crashed.
Now moving to your question if you want to go back to the fragment from the activty : Stock INFO you just need to call finish() it will finish the current activity(Stock Info) and the fragment which is in background will be resumed.I had same problem and solved by this way .This is the onCreate Method of Activity(in your case it is for StockInfo class).Have a look:
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.setmCallBack(new IResultCallback() {
#Override
public void result(Result lastResult) {
if (lastResult!=null) {
finish();// by this line I have killed the current activity
}
else
{
Toast.makeText(getActivity(), "NotScan: ", Toast.LENGTH_SHORT).show();
}
}
});
}
Ok look,
startActivity(intent);
this method name startActivity. So it will start another activity not fragment.
You can See & read the fragment:
http://developer.android.com/guide/components/fragments.html
Add fragment to go back to manually to the backstack.
FragmentTransaction transaction = getFragmentManager().beginTransaction();
YourFragmentName myFragment = new YourFragmentName();
transaction.replace(R.id.fragment_container, myFragment);
transaction.addToBackStack(null);
transaction.commit();
And There is several methods here. Just take a look:-
http://developer.android.com/reference/android/app/FragmentManager.html#popBackStack()
If you want to go back to the fragment , you can do this :
getFragmentManager().popBackStack();
I'm converting an app to use fragments using the compatibility library.
Now currently I have a number of activities (A B C D) which chain onto one another, D has a button 'OK' which when pressed calls finish which then bubbles up through onActivityResult() to additionally destroy C and B.
For my pre Honycomb fragment version each activity is effectively a wrapper on fragments Af Bf Cf Df. All activities are launched via startActivityForResult() and onActivityResult() within each of the fragments can happily call getActivity().finish()
The problem that I am having though is in my Honeycomb version I only have one activity, A, and fragments Bf, Cf, Df are loaded using the FragmentManager.
What I don't understand is what to do in Df when 'OK' is pressed in order to remove fragments Df, Cf, and Bf?
I tried having the fragment popping itself off the stack but this resulted in an exception. onActivityResult() is useless because I have not loaded up the fragment using startActivityForResult().
Am I thinking about this completely the wrong way? Should I be implementing some sort of listener that communicates with either the parent fragment or activity in order to do the pop using the transaction manager?
While it might not be the best approach the closest equivalent I can think of that works is this with the support/compatibility library
getActivity().getSupportFragmentManager().beginTransaction().remove(this).commit();
or
getActivity().getFragmentManager().beginTransaction().remove(this).commit();
otherwise.
In addition you can use the backstack and pop it. However keep in mind that the fragment might not be on the backstack (depending on the fragmenttransaction that got it there..) or it might not be the last one that got onto the stack so popping the stack could remove the wrong one...
You can use the approach below, it works fine:
getActivity().getSupportFragmentManager().popBackStack();
What I don't understand is what to do in Df when 'OK' is pressed in order to remove fragments Df, Cf, and Bf?
Step #1: Have Df tell D "yo! we got the OK click!" via calling a method, either on the activity itself, or on an interface instance supplied by the activity.
Step #2: Have D remove the fragments via FragmentManager.
The hosting activity (D) is the one that knows what other fragments are in the activity (vs. being in other activities). Hence, in-fragment events that might affect the fragment mix should be propagated to the activity, which will make the appropriate orchestration moves.
You should let the Activity deal with adding and removing Fragments, as CommonsWare says, use a listener. Here is an example:
public class MyActivity extends FragmentActivity implements SuicidalFragmentListener {
// onCreate etc
#Override
public void onFragmentSuicide(String tag) {
// Check tag if you do this with more than one fragmen, then:
getSupportFragmentManager().popBackStack();
}
}
public interface SuicidalFragmentListener {
void onFragmentSuicide(String tag);
}
public class MyFragment extends Fragment {
// onCreateView etc
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
try {
suicideListener = (SuicidalFragmentListener) activity;
} catch (ClassCastException e) {
throw new RuntimeException(getActivity().getClass().getSimpleName() + " must implement the suicide listener to use this fragment", e);
}
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
// Attach the close listener to whatever action on the fragment you want
addSuicideTouchListener();
}
private void addSuicideTouchListener() {
getView().setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
suicideListener.onFragmentSuicide(getTag());
}
});
}
}
In the Activity/AppCompatActivity:
#Override
public void onBackPressed() {
if (mDrawerLayout.isDrawerOpen(GravityCompat.START)) {
// if you want to handle DrawerLayout
mDrawerLayout.closeDrawer(GravityCompat.START);
} else {
if (getFragmentManager().getBackStackEntryCount() == 0) {
super.onBackPressed();
} else {
getFragmentManager().popBackStack();
}
}
}
and then call in the fragment:
getActivity().onBackPressed();
or like stated in other answers, call this in the fragment:
getActivity().getSupportFragmentManager().beginTransaction().remove(this).commit();
If you are using the new Navigation Component, is simple as
findNavController().popBackStack()
It will do all the FragmentTransaction in behind for you.
See if your needs are met by a DialogFragment. DialogFragment has a dismiss() method. Much cleaner in my opinion.
I create simple method for that
popBackStack(getSupportFragmentManager());
Than place it in my ActivityUtils class
public static void popBackStack(FragmentManager manager){
FragmentManager.BackStackEntry first = manager.getBackStackEntryAt(0);
manager.popBackStack(first.getId(), FragmentManager.POP_BACK_STACK_INCLUSIVE);
}
It's work great, have fun!
OnCreate:
//Add comment fragment
container = FindViewById<FrameLayout>(Resource.Id.frmAttachPicture);
mPictureFragment = new fmtAttachPicture();
var trans = SupportFragmentManager.BeginTransaction();
trans.Add(container.Id, mPictureFragment, "fmtPicture");
trans.Show(mPictureFragment); trans.Commit();
This is how I hide the fragment in click event 1
//Close fragment
var trans = SupportFragmentManager.BeginTransaction();
trans.Hide(mPictureFragment);
trans.AddToBackStack(null);
trans.Commit();
Then Shows it back int event 2
var trans = SupportFragmentManager.BeginTransaction();
trans.Show(mPictureFragment); trans.Commit();
If you need to popback from the fourth fragment in the backstack history to the first, use tags!!!
When you add the first fragment you should use something like this:
getFragmentManager.beginTransaction.addToBackStack("A").add(R.id.container, FragmentA).commit()
or
getFragmentManager.beginTransaction.addToBackStack("A").replace(R.id.container, FragmentA).commit()
And when you want to show Fragments B,C and D you use this:
getFragmentManager.beginTransaction.addToBackStack("B").replace(R.id.container, FragmentB, "B").commit()
and other letters....
To return to Fragment A, just call popBackStack(0, "A"), yes, use the flag that you specified when you add it, and note that it must be the same flag in the command addToBackStack(), not the one used in command replace or add.
You're welcome ;)
To Close a fragment while inside the same fragment
getActivity().onBackPressed();
kotlin -
requireActivity().onBackPressed()
parentFragmentManager.apply {
val f = this#MyFragment
beginTransaction().hide(f).remove(f).commit()
}
Why not just:
getActivity().finish();