I've been researching this topic but so far no luck. Basically I'm replacing a fragment (A) with another one (B) using FragmentTransaction.replace. In this other fragment (B) I have a 'Cancel' button in the toolbar which when pressed pops back to the previous transaction (A) by calling getActivity().getSupportFragmentManager().popBackStackImmediate().
The problem is I need to update the Activity toolbar to display a different title when I'm showing fragment A and fragment B. I can't seem to find a method which gets called in fragment A whenever I go from A -> B -> A to inform me that it is visible again. The idea is to set the toolbar title in this callback which I cannot seem to find.
Can anyone point me in the right direction please?
Cheers.
Edit:
Method I call to replace the fragment with another one is as follows:
public static void replaceFragment(FragmentActivity parentActivity, int fragmentToReplaceId, Fragment withFragment, Integer enterAnim, Integer exitAnim)
{
FragmentManager fragmentManager;
FragmentTransaction transaction;
fragmentManager = parentActivity.getSupportFragmentManager();
transaction = fragmentManager.beginTransaction();
if ( (null != enterAnim) &&
(null != exitAnim) )
{
transaction.setCustomAnimations(enterAnim, exitAnim);
}
transaction.replace(fragmentToReplaceId, withFragment);
transaction.addToBackStack(null);
transaction.commit();
}
You can inform by overriding method onResume() in fragment and sending the message to activity or changing the Toolbar directly.
#Override
public void onResume() {
super.onResume();
((AppCompatActivity) getActivity()).getSupportActionBar().setTitle("Title");
}
In one activity, when replace A ---> B (A and B both are fragments), can use this call-back:
#Override
public void onAttachFragment(Fragment fragment) {
}
Solved by creating a simple static method in fragment A as follows:
public static void updateActivityTitle(FragmentActivity activity)
{
activity.setTitle(kActivityTitle);
}
Then I'm calling this method in fragment B as follows:
// cancel button has been pressed
private void cancel()
{
INV_CustomersFragment.updateActivityTitle(getActivity());
getActivity().getSupportFragmentManager().popBackStackImmediate();
}
Not ideal but it gets the job done. Any other solution involving a proper callback would be better
Update:
A better solution is the one described by #Rani at Fragment's onResume() not called when popped from backstack. This is more elegant and more maintainable, in fact I implemented this solution in my project. Compared to an equivalent solution for iOS this is still messy if you ask me, still seems the way to go.
Related
I am using one activity for tabactivity with viewpager and attached fragmentA.when i want to move fragmentB ,replaced fragmentB with present fragmentA.I need to find solution for onbackpress in FragmentB refresh fragmentA wihtout changing Backstack because i used nearly ten fragments in one tab.
Is there any method in fragment life cycle
When Fragment B over Fragment A, fragment A is onPause(). After backpress, fragment A is onResume(). So you can create a boolean to observe this change.
In Fragment A
private boolean isBackFromB;
#Override
public void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
isBackFromB=false;
}
#Override
public void onPause() {
super.onPause();
isBackFromB = true;
}
#Override
public void onResume() {
super.onResume();
updateUI();
if (isBackFromB) //Do something
}
View pager does not always hold it's fragments in memory, so you have to handle 2 scenarios:
1 - fragment is recreated - just read data from wherever you hold them and show in ordinary way.
2 - fragment is modified from outside while still has been held by ViewPager, and as I understand this is what concerns you.
What you can do is to create this listener and then notify fragment that it was shown again and possibly should reload it's data.
More complex answer for communicating between different application's components is using some event bus like Otto.
override onBackPressed() method in Activity, add all fragment in backstack.
#Override
public void onBackPressed() {
FragmentManager manager =getFragmentManager();
int count = manager.getBackStackEntryCount();
if (count == 0) {
super.onBackPressed();
} else {
manager.popBackStack();
}
}
Given an Activity that acts as a Home page (it never closes) that launches various fragments, how to know when the Activity is visible to the user?
From what I have observed, when I open a fragment the lifecycle for the Activity never changes, onPause() is not called. And when I close the fragment, onResume() is not called on my Activity.
Here is how I am starting my fragments, I am using this method and passing the fragment I want to launch to it.
public void addFragment(int containerId, Fragment fragment, boolean addToBackStack) {
// Check if the fragment has been added already. If so, then
// don't add the fragment.
Fragment temp = mFragmentManager.findFragmentByTag(fragment.getClass().getName());
if(temp != null && temp.isAdded()) {
return;
}
FragmentTransaction ft = mFragmentManager.beginTransaction();
ft.add(containerId, fragment, fragment.getClass().getName());
if(addToBackStack)
ft.addToBackStack(null);
ft.commit();
}
What is the methodology for indicating that my Activity is visible again? Thanks in advance!
in the oncreate method of your home activity, call
mFragmentManager.addOnBackStackChangedListener(this) ;
and then define
#Override
public void onBackStackChanged() {
int backStackCount = mFragmentManager.getBackStackEntryCount();
if(backStackCount == 0) {} //back to home screen
}
Your Activity is always Visible even if thousand Fragments are showing at the same time, for the sake of understanding Fragments are just Custom-Views, and the Fragment gives a helping hand in handling your View, so onPause() on your activity does not need to called when a Fragment dies or is born,just like inflating a View.
Just like Sir #Tim Mutton said, you need to check your BackStack to know if you are back, or you can use the ViewGroup method ViewGroup.indexOfChild(View child) - this method will an int of value getChildCount()-1 which means its on top of its fellow sibblings..
Hope it helps
I know that question about refreshing actionbar title has already been answered.
But my problem is quiet different.
I use fragments with add method and not with replace method for some reasons. So previous fragment are not destroy and when back, previous fragment aren't not recreating.
This is my configuration :
Fragment A with title "FragA" > Fragment B with title "FragB"
When I go back to Fragment A from Fragment B the actionbar title should be "FragA" but it stay "FragB".
The problem is with add method Fragment A is not recreating and I didn't find event to refresh it.
The only simple solution I found for now is :
1- fragB.OnResume : save previous action bar title
2- fragB.OnDestroyView : restore previous actionbar title
With this solution, the result is ok, but I found this solution is not very clean. Is there a better way to refresh actionbartitle using add method with fragments ?
You can override your onBackPressed of your activity and each time you pressed it you then get the name of the fragment from the backstack to know which fragment you current at.
sample:
#Override
public void onBackPressed() {
super.onBackPressed();
int framentCount = this.getFragmentManager().getBackStackEntryCount();
if(framentCount != 0)
{
FragmentManager.BackStackEntry backEntry=getFragmentManager().getBackStackEntryAt(framentCount-1);
String str=backEntry.getName(); //the tag of the fragment
if(str.equals("fragA"))
//set the actionbar title to FragA
else if(str.equals("fragB"))
//set the actionbar title to FragB
}
FragA myFragA = (FragA)getFragmentManager().findFragmentByTag("MY_FRAGMENTA_A_TAG");
if (myFragA.isVisible()) {
//action bar.title="title first fragment"
}
}
Now to know which fragment is which you need to put a tag to your fragment when you add / replace it to the backstack. Also make sure that you call addToBackStack to put the fragments to the backstack.
FragmentTransaction.add(int containerViewId, Fragment fragment, String tag)
FragmentTransaction.replace(int containerViewId, Fragment fragment, String tag)
Call the below line of code in all your fragments onResume() callback. you wouldnt need to save the title.
((YourFragmentActivity) getActivity()).setActionBarTitle(YOUR_TITLE);
it should help.
Put a public static string called tag on your fragments, then use this where the tag is. More maintainability.
Why - This means if you want to change the tag, you only have to change it in one place, less refactoring. (Its used also on add, replace functions - see Rod's answer if confused)
My implementation of the solution is similar to how Rod solved the issue in his edited answer except a lot less code.
#Override
public void onBackPressed() {
super.onBackPressed();
try {
if (getFragmentManager().findFragmentByTag(FragA.tag) != null) {
if (getFragmentManager().findFragmentByTag(FragA.tag).isVisible()) {
getActionBar().setTitle(R.string.FragA_title);
}
}
if (getFragmentManager().findFragmentByTag(FragB.tag) != null) {
if (getFragmentManager().findFragmentByTag(FragB.tag).isVisible()) {
getActionBar().setTitle(R.string.FragB_title);
}
}
}
catch (NullPointerException e) {
}
}
eg of static tag use
FragmentTransaction.add(int containerViewId, Fragment fragment, FragA.tag)
#Override
public void onStop() {
super.onStop();
((AppCompatActivity) getActivity()).getSupportActionBar().setTitle("Title");
}
Override the onStop() method in your current fragment, and gives the title name of your previous fragment.
Related Question.
I put together a simple app that goes like this:
Activity -> FirstFragment
Activity: onCreate() -> createFirstFragment()
FirstFragment firstFragment = (FirstFragment) getSupportFragmentManager().findFragmentByTag(FirstFragment.TAG);
if (firstFragment == null)
{
firstFragment = FirstFragment.newInstance();
getSupportFragmentManager()
.beginTransaction()
.add(R.id.firstFragmentContainer, firstFragment, FirstFragment.TAG)
.hide(firstFragment)
//.addToBackStack(null)
.commit();
}
Plain and simple, during onCreate() add and hide a fragment so that I can do show/hide animations later.
Now, my question is this: why does the Activity/FragmentManager not remember this transaction (regardless of whether I .addToBackStack() or setRetainInstance(true) on the fragment) when the activity is killed and recreated? You can test this by checking the Do not keep activities developer option. Start the app, firstFragment is hidden as expected, minimize and come back, and viola! firstFragment is there for all the world to see!
I would expect that this sort of thing would be managed by Android, or do I need to specifically record all my transactions and repeat them when the app is recreated?
Any help/advice would be greatly appreciated!
Edit: Also see related logged bug
Use FragmentStatePagerAdapter like below in your main activity. This internally calls 'onSaveInstanceState' of the fragments and hence keeps the track of the changes you made and retains the transactional states
class MyAdapter extends FragmentStatePagerAdapter {
public MyAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
// your code here
}
#Override
public int getCount() {
// returns no. of fragments count. in my case it is 4
return 4;
}
onCreate() in mainactivity generally looks like this:
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView (R.layout.scrollabletabs_main);
viewPager = (ViewPager) findViewById (R.id.pager);
FragmentManager fragManager = getSupportFragmentManager();
viewPager.setAdapter(new MyAdapter(fragManager));
}
From
http://developer.android.com/training/basics/fragments/fragment-ui.html it is mentioned that,
Note: When you remove or replace a fragment and add the transaction to the back stack, the fragment that is removed is stopped (not destroyed). If the user navigates back to restore the fragment, it restarts. If you do not add the transaction to the back stack, then the fragment is destroyed when removed or replaced.
I've seen quite a few questions on SO about Fragments and I still can't seem to figure out if what I want to do is possible, and more so if my design pattern is just flawed and I need to re-work the entire process. Basically, like most questions that have been asked, I have an ActionBar with NavigationTabs (using ActionBarSherlock), then within each Tab there is a FragementActivity and then the FragmentActivities push new Fragments when a row is selected (I'm trying to re-create an iOS Project in Android and it's just a basic Navigation based app with some tabs that can drill down into specific information). When I click the back button on the phone the previous Fragment is loaded but the Fragment re-creates itself (so the WebServices are called again for each view) and this isn't needed since the information won't change in a previous view when going backwards. So basically what I want to figure out is how do I setup my Fragments so that when I push the back button on the phone, the previous Fragment is just pulled up with the previous items already created. Below is my current code :
//This is from my FragmentActivity Class that contains the ActionBar and Tab Selection Control
#Override
public void onTabSelected(ActionBar.Tab tab, FragmentTransaction ft) {
// TODO Auto-generated method stub
int selectedTab = tab.getPosition();
if (selectedTab == 0) {
SalesMainScreen salesScreen = new SalesMainScreen();
ft.replace(R.id.content, salesScreen);
}
else if (selectedTab == 1) {
ClientMainScreen clientScreen = new ClientMainScreen();
ft.replace(R.id.content, clientScreen);
}.....
//This is within the ClientMainScreen Fragment Class, which handles moving to the Detail Fragment
row.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
//Do something if Row is clicked
try{
String selectedClientName = clientObject.getString("ClientName");
String selectedClientID = clientObject.getString("ClientID");
String selectedValue = clientObject.getString("ClientValue");
transaction = getFragmentManager().beginTransaction();
ClientDetailScreen detailScreen = new ClientDetailScreen();
detailScreen.clientID = selectedClientID;
detailScreen.clientName = selectedClientName;
detailScreen.clientValue = selectedValue;
int currentID = ((ViewGroup)getView().getParent()).getId();
transaction.replace(currentID,detailScreen);
transaction.addToBackStack(null);
transaction.commit();
}
catch (Exception e) {
e.printStackTrace();
}
}
});....
//And then this is the Client Detail Fragment, with the method being called to Call the Web Service and create thew (since what is displayed on this screen is dependent on what is found in the Web Service
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup group, Bundle saved) {
return inflater.inflate(R.layout.clientdetailscreen, group, false);
}
#Override
public void onActivityCreated (Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
//Setup Preferences File Link
this.preferences = PreferenceManager.getDefaultSharedPreferences(getActivity());
//initialize the table object
mainTable = (TableLayout)getActivity().findViewById(R.id.mainTable);
//setup the detail table
setupRelatedClientSection();
}
The Client Detail Screen can then drill down one more time, using the same method as the Client Main Screen but when I go back from that new screen to the Detail Screen the seuptRelatedClientSection() method is called again and so the entire Fragment is rebuilt when really I just want to pull up a saved version of that screen. Is this possible with my current setup, or did I approach this the wrong way?
Try using fragementTransaction.add instead of replace
I believe that you are looking for show() and hide().
I think you can still add them to the backstack.
transaction.hide(currentFragment);
transaction.show(detailScreen);
transaction.addToBackStack(null);
transaction.commit();
I didnt have my code to look at but i believe this is how it would go... Try it out unless someone else has a better way.
I have not tried the backstack with show() hide() but i believe that it takes the changes that are made before the transactions commit and will undo them if the back button is pressed. Please get back to me on this cause i am interested to know.
You also have to make sure that the detail fragment is created before you call this. Since it is based on the click of someitem then you should probably create the details fragment every time you click to make sure the correct details fragment is created.
I'm posting this answer for people who may refer this question in future.
Following code will demonstrate how to open FragmentB from FragmentA and going back to FragmentA from FragmentB (without refreshing FragmentA) by pressing back button.
public class FragmentA extends Fragment{
...
void openFragmentB(){
FragmentManager fragmentManager =
getActivity().getSupportFragmentManager();
FragmentB fragmentB = FragmentB.newInstance();
if (fragmentB.isAdded()) {
return;
} else {
fragmentManager.
beginTransaction().
add(R.id.mainContainer,fragmentB).
addToBackStack(FragmentB.TAG).
commit();
}
}
}
public class FragmentB extends Fragment{
public static final String TAG =
FragmentB.class.getSimpleName();
...
public static FragmentB newInstance(){
FragmentB fragmentB = new FragmentB();
return fragmentB;
}
#Override
public void onResume() {
super.onResume();
// add this piece of code in onResume method
this.getView().setFocusableInTouchMode(true);
this.getView().requestFocus();
}
}
In your MainActivity override onBackPressed()
class MainActivity extends Activity{
...
#Override
public void onBackPressed() {
if (getFragmentManager().getBackStackEntryCount() > 0) {
getFragmentManager().popBackStack();
} else {
super.onBackPressed();
}
}
}
You're right, there has been a number of previous questions / documentation on the topic ;)
The documentation on Fragments, specifically the section about Transactions and Saving State, will guide you to the answer.
http://developer.android.com/guide/components/fragments.html#Transactions
http://developer.android.com/guide/components/activities.html#SavingActivityState
Android - Fragment onActivityResult avoid reloading
Fragments can have support for onSaveInstanceState but not onRestoreInstanceState, so if you want to save a reference to the table views, save them to the Bundle and you can access the saved view in your onActivityCreated method. You could also use the Fragments back stack.
This guide/tutorial has very detailed instructions/examples on the back stack and retaining fragment state.
Good luck