I've been researching a solution to my problem but not a single result fixes my problem.
I have five Java activities. Each activity has five buttons, four to the other activities and one to itself. It's basically just a bar of bottoms at the bottom of the page.
My issue is that let's say I'm in one activity, and then I click that button to the activity again, it opens and loads an entirely new activity. And then when I click back, it shows the previous activity open as I left it. But if I press it ten times, I need to click back ten times. Also, if I switch between each activity twice and I want to click back to main to exit, I need to click back ten times instead of five.
I want it to be such that when I click a button, it opens the activity. If I press the button again, it does nothing if I'm in that activity. And if I'm switching between activities and I repress an activity I already opened, I want that to be brought to the top of the stack from its lower location, not added. So at most, I only want five activities running.
It's a very confusing problem as I see people suggesting to use intent flags, which I'm not sure if I place them in the manifest, which does nothing with I try. And I've seen people suggest using LaunchMode single instance, which also does nothing.
I really think fragments are the best method here. And yes, it's a little tricky but you can use fragments within fragments. For navigating without creating extra instances, I think you might be looking for something along the lines of this:
public boolean onNavigationItemSelected(MenuItem item) {
// Handle navigation view item clicks here.
int id = item.getItemId();
if(id == R.id.nav_home){
Fragment newFragment;
FragmentManager fragmentManager = getSupportFragmentManager();
// Look for fragment by tag
Fragment foundFragment = fragmentManager.findFragmentByTag(MAIN_FRAGMENT);
if(foundFragment != null) { //if fragment's already in the backstack
newFragment = foundFragment; //replace fragment with backstack fragment
}else{
newFragment = new MainFragment(); // use a new fragment instance
}
// Add new fragment instance to fragment manager
fragmentManager.beginTransaction()
.replace(R.id.fragment_container, newFragment, MAIN_FRAGMENT)
.addToBackStack(MAIN_FRAGMENT)
.commit();
}
// ...
}
Related
I have an activity with two containers for fragments, container_left and container_right.
At the beginning of navigation, a list fragment is in container_left, and the fragment that loads into container_right is a screen with several buttons.
When someone selects a button in the fragment in container_right, that fragment replaces the one in container_left, and a new fragment is loaded into container_right. At this point, I have saved this transaction to the backstack. If the back button is pressed at this point, the original list loads into container_left, and the button fragment loads into container_right. But if the person selects another button (now in the left hand frame), it adds a different fragment to the right hand container. I don't want to add the new transaction to the backstack, as I don't want to save the transactions where only fragment_container_right changes. I want the back button to only change the positions of the fragments.
The problem is, the transaction in the backstack is looking for the original fragment that was removed in the right frame, and since that has changed, it doesn't remove the new fragment, so the button fragment appears ON TOP of the new fragment in container_right.
I have been messing with this for a while, but I can't figure this one out.
How can I set this up so that when it pops the stack, any fragments currently in container_right are removed, even if they aren't the ones that were there when the transaction was committed?
here is a sample of what I have so far for loading the frames. As you can see, I check to see if the control buttons are in the left frame before committing, so it isn't loading a new instance on every button push, and I do the same for each fragment loading into container_right, so I'm not creating a new fragment if someone hits the button for a fragment that is already loaded. The only issue left is the backstack transaction.
if (!(controlsInLeftFrame)) {
getFragmentManager().beginTransaction().
replace(R.id.fragment_container_right, fragAD).
replace(R.id.fragment_container_left, fragRECB).addToBackStack(null).commit();
} else if (!(getFragmentManager().findFragmentById(R.id.fragment_container_right) instanceof FragAttributeDescription)){
getFragmentManager().beginTransaction().
replace(R.id.fragment_container_right, fragAD).commit();
}
}
if (message.equals("Movement")) {
FragRaceEditorMovement fragRM = new FragRaceEditorMovement();
fragRM.setArguments(bundle);
if (!(controlsInLeftFrame)) {
getFragmentManager().beginTransaction().
replace(R.id.fragment_container_right, fragRM).
replace(R.id.fragment_container_left, fragRECB).addToBackStack(null).commit();
} else if (!(getFragmentManager().findFragmentById(R.id.fragment_container_right) instanceof FragRaceEditorMovement)){
getFragmentManager().beginTransaction().
replace(R.id.fragment_container_right, fragRM).commit();
}
Okay, I figured it out.
overriding onBackPressed() worked. I had tried it once before, but realized that I had forgotten to put super.onBackPressed() AFTER removing the right hand fragment.
public void onBackPressed() {
getFragmentManager().beginTransaction().remove(getFragmentManager().findFragmentById(R.id.fragment_container_right)).commit();
super.onBackPressed();
}
this appears to have solved the problem adequately
I have an app with a main activity which loads a navigation drawer, and a pair of fragments that load in that activity ...
In the navigation drawer I have 4 options A, B, C and D ... the first one loads FragmentA on my activity and the last 3 load FragmentB ..
FragmentA displays a list of elements and, upon selecting one of these elements FragmentB is used to load its content... I want to change the home (hamburger/drawer) icon on FragmentB for the up icon when initiating from FragmentA (and change the corresponding behavior to make a popstack on select).. I have no problem with this using setDisplayHomeAsUpEnabled(true), but since all this is occurring inside one activity if I then select one other option (say B) from the navigation drawer the up icon will still be showing (it its also showing on the popped fragment)...
if I use setDisplayHomeAsUpEnabled(false) all this do is hide the home/up button from the toolbar, I need to recover the home button and make sure this will be shown when FragmentB is initiated from the drawer menu ...
Does this problem ring a bell to anyone? or am I just using fragments the wrong way? .. any advice will be appreciated
EDIT
this is more or less what I have in code
In Main Activity .. as the onNavigationItemSelected(MenuItem item) for the drawer I have a something like this ...
switch(optionNumber) {
case 0:
fragment = FragmentA.newInstance(optionNumber);
break;
default:
fragment = FragmentB.newInstance(optionNumber);
break;
}
Fragment frag = fragmentManager.findFragmentByTag("current_fragment");
if (frag != null && frag.getClass() == FolderFragment.class){
((FolderFragment)frag).resetScroll();
}
fragmentManager.popBackStack(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);
fragmentManager.beginTransaction().replace(R.id.content, fragment, "current_fragment").commit();
which selects the fragment to load according to the option selected..
In FragmentA I'm calling FragmentB with this ..
FragmentB fFragment = FragmentB.newInstance(position);
Bundle args = new Bundle();
args.putString("filter", "something"); fFragment.setArguments(args);
mActivity.getSupportFragmentManager().beginTransaction()
.replace(R.id.flContent, fFragment, "current_fragment")
.addToBackStack(null)
.commit();
Preserving the fragment in the stack
And in fragmentB inside onResume() function I got something like...
String filter = getArguments().getString("filter", null);
if (type != null) {
mActivity.setTitle(title);
mActivity.getSupportActionBar().setDisplayShowHomeEnabled(true);
}else {
/*mActivity.getSupportActionBar().setDisplayHomeAsUpEnabled(false);
mActivity.getSupportActionBar().setDisplayShowHomeEnabled(true);
mActivity.getSupportActionBar().setHomeButtonEnabled(true);
mActivity.getSupportActionBar().setIcon(R.mipmap.ic_menu);*/
}
So When I'm creating fragmentB I check for arguments and see if it comes from fragmentA or not ( I could also check the fragmentmanager backstack and see if there's something)... there I just change the drawer icon with setDisplayShowHomeEnabled(true) ... leaving the back arrow, if I return to FragmentA (via onBackPressed()) FragmentA shows the arrow and I need it to show the original drawer icon ... the same happens if I select an option from the drawer menu ...
Does this gives more clarity to my issue ?... I have some commented code there because it doesn't work .. if I activate the line with setDisplayHomeAsUpEnabled(false).. the icon just disappears from the activity (which is the intended result of the function as far as I know)...
After a while I finally found this post
Switching between Android Navigation Drawer image and Up caret when using fragments
I guess that when involving a Drawer in the interface you might need to handle this issue with that component... this post gave me the answer.
Particular notice to the last comment by Wolfram Rittmeyer
My Application has one Activity with a layout (FrameLayout) for many fragments.
At the start of the Application it displays a list of Places (PlacesFragment).
When a Place is clicked, a Fragment that displays a list of cams (CamFragment) is added. Inside this fragment there is also a button "info".
When the user press the "info" button a new fragment (InfoPlaceFragment) that displays information about the place, is added.
Here is a graphical explanation:
I want to be able to go back to "CamFragment(B)" from "InfoPlaceFragment(C)", and to go back to "PlacesFragment(A)" from "CamFragment(B)".
One Question:
1) Is it possible to realize this or an alternative solution is better?
------- EDIT -------
SOLUTION:
In the "MainActivity.java":
onPlaceParse() // This method is called when the data from the server is received:
// Here I create the "PlaceFragment"
fManager = getSupportFragmentManager();
fragmentPlaces = new PlacesFragment();
fManager.beginTransaction()
.replace(R.id.fragment_list_container, fragmentPlaces)
.commit();
onResortSelected // This method is called when the resort is selected
fragmentCams = new CamsFragment();
fManager.beginTransaction()
.replace(R.id.fragment_list_container, fragmentCams)
.addToBackStack(null)
.commit();
onButtonInfoSelected // This method is called when the btn info is selected
fragmentInfo = new InfoResortFragment();
fManager = getSupportFragmentManager();
fManager.beginTransaction()
.replace(R.id.fragment_list_container, fragmentInfo, "Info")
.addToBackStack(null)
.commit();
When you press the back button, if you are in the "Info Fragment" it returns to "PlaceFragment" and if you are in the "CamsFragment" it returns to "PlacesFragment".
This is possible, you need to call addToBackStack(null) in the fragment transactions.
Reference: Providing Proper Back Navigation
When you create your FragmentTransaction that will add/remove/replace (or whatever pattern you are using) the Fragments, just make sure to call addToBackStack(). Then, when the user presses the back button, the system will automatically cycle back through the entries added to the back stack, in reverse order from how they were originally added. No additional work is required on your part! :)
I have an activity that have some buttons and some fragments.
If I click on button A, i'll show Fragment "FragA". When I'm in "FragA", I can perform some actions like choose a picture from gallery and I need to stay in "FragA" after choose picture.
But when I choose picture, I return to Activity and "FragA" is hidden.
How can perform an action and still in same Fragment or display correct fragment in Activity?
You can recreate fragment again and replace it in your Activity with using modification of this code:
if (currentState == STATE_MAIN_FRAGMENT) {
return;
}
mainScreenFragment = (MainScreenFragment) getSupportFragmentManager().findFragmentByTag(MainScreenFragment.TAG);
if (mainScreenFragment == null) {
mainScreenFragment = new MainScreenFragment();
}
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.flFragmentContainer, mainScreenFragment, MainScreenFragment.TAG);
fragmentTransaction.commit();
First "if" checks if the fragment is set or not. It is not required but it's a good practice. It prevents you from replacing fragment when it is not necessary.
And there is one thing strange for me. Because you said <<"FragA" is hidden>> - that means it was already set but container is not visible? Then yourFragmentContainer.setVisiblity(View.VISIBLE); in on Activity result.
And the last thing that could help you is to retain the fragment so it won't be ever destroyed and recreated again. Some helpful links:
Understanding Fragment's setRetainInstance(boolean)
http://developer.android.com/reference/android/app/Fragment.html#setRetainInstance(boolean)
Or you can just copy-paste what is in your Button's OnClickListener so it happens onActivityResult too.
Scenario what i'm trying to achieve:
Loading activity with two frame containers (for list of items and for details).
At the app launch time add listFragment in listFrame and some initial infoFragment in detailsFrame containers.
Navigating through list items without adding each detail transaction to back stack (want to keep only infoFragment in stack).
As soon as user hit back button (navigate back) he falls back to intial infoFragment what was added in launch time.
If sequential back navigation fallows then apps exit.
My code:
protected override void OnCreate(Bundle savedInstanceState)
{
...
var listFrag = new ListFragment();
var infoFrag = new InfoFragment();
var trans = FragmentManager.BeginTransaction();
trans.Add(Resource.Id.listFrame, listFrag);
trans.Add(Resource.Id.detailsFrame, infoFrag);
trans.Commit();
...
}
public void OnItemSelected(int id)
{
var detailsFrag = DetailFragment.NewInstance(id);
var trans = FragmentManager.BeginTransaction();
trans.Replace(Resource.Id.detailsFrame, detailsFrag);
if (FragmentManager.BackStackEntryCount == 0)
{
trans.AddToBackStack(null);
}
trans.Commit();
}
My problem:
After back button has been hit, infoFrag is overlapped with previous detailFrag! Why?
You can do this:
if (getSupportFragmentManager().getBackStackEntryCount() > 0) {
getSupportFragmentManager().popBackStack(getSupportFragmentManager().getBackStackEntryAt(0).getId(), getSupportFragmentManager().POP_BACK_STACK_INCLUSIVE);
} else {
super.onBackPressed();}
In your activity, so you to keep first fragment.
You shouldn't have, in your first fragment, the addToBackStack. But, in the rest, yes.
Very nice explanation by Budius. I read his advice and implemented similar navigation, which I would like to share with others.
Instead of replacing fragments like this:
Transaction.remove(detail1).add(detail2)
Transaction.remove(detail2).add(detail3)
Transaction.remove(detail3).add(detail4)
I added a fragment container layout in the activity layout file. It can be either LinearLayout, RelativeLayot or FrameLayout etc.. So in the activity on create I had this:
transaction.replace(R.id.HomeInputFragment, mainHomeFragment).commit();
mainHomeFragment is the fragment I want to get back to when pressing the back button, like infoFrag. Then, before EVERY NEXT transaction I put:
fragmentManager.popBackStackImmediate();
transaction.replace(R.id.HomeInputFragment, frag2).addToBackStack(null).commit();
or
fragmentManager.popBackStackImmediate();
transaction.replace(R.id.HomeInputFragment, frag3).addToBackStack(null).commit();
That way you don't have to keep track of which fragment is currenty showing.
The problem is that the transaction that you're backing from have two steps:
remove infoFrag
add detailsFrag (that is the first1 detail container that was added)
(we know that because the documentation This is essentially the same as calling remove(Fragment) for all currently added fragments that were added with the same containerViewId and then add(int, Fragment, String) with the same arguments given here. )
So whenever the system is reverting that one transaction is reverting exactly those 2 steps, and it say nothing about the last detailFrag that was added to it, so it doesn't do anything with it.
There're two possible work arounds I can think on your case:
Keep a reference on your activity to the last detailsFrag used and use the BackStackChange listener to whenever the value change from 1 to 0 (you'll have to keep track of previous values) you also remove that one remaining fragment
on every click listener you'll have to popBackStackImmediatly() (to remove the previous transaction) and addToBackStack() on all transactions. On this workaround you can also use some setCustomAnimation magic to make sure it all looks nice on the screen (e.g. use a alpha animation from 0 to 0 duration 1 to avoid previous fragment appearing and disappearing again.
ps. I agree that the fragment manager/transaction should be a bit more clever to the way it handles back stack on .replace() actions, but that's the way it does it.
edit:
what is happening is like this (I'm adding numbers to the details to make it more clear).
Remember that .replace() = .remove().add()
Transaction.remove(info).add(detail1).addToBackStack(null) // 1st time
Transaction.remove(detail1).add(detail2) // 2nd time
Transaction.remove(detail2).add(detail3) // 3rd time
Transaction.remove(detail3).add(detail4) // 4th time
so now we have detail4 on the layout:
< Press back button >
System pops the back stack and find the following back entry to be reversed
remove(info).add(detail1);
so the system makes that transaction backward.
tries to remove detail1 (is not there, so it ignores)
re-add(info) // OVERLAP !!!
so the problem is that the system doesn't realise that there's a detail4 and that the transaction was .replace() that it was supposed to replace whatever is in there.
You could just override onBackPressed and commit a transaction to the initial fragment.
I'm guessing but:
You've added the transaction to replace infoFrag with 1st detailsFrag into the backstack.
But then you replace 1st detailsFrag with 2nd detailsFrag.
At this point when you click back, the fragment manager cannot cleanly replace 1st detailsFrag with infoFrag as 1st detailsFrag has already been removed and replaced.
Whether the overlapping behaviour is expected or not I don't know.
I would suggest debugging the Android core code to see what it is doing.
I'm not sure whether you can achieve without say overriding Activity::onBackPressed() and doing the pops yourself having added all transactions to the backstack.