Receive a unique intent/bundle value in activity - android

I have a
1) MainActivity.
2) Fragment 1 (Listview)
3) Fragment 2 (Listview)
4) Fragment 3 (Textview)
I can successfully launch Fragment 1 when the app is first started.
Then, once i click on any listitem on Fragment 1, Fragment 2 is launched. I've handled both these fragments with the following condition in order to differentiate inside my MainActivity
if (this.getIntent().getExtras()
== null) {
fragmentManager.beginTransaction()
.replace(R.id.restaurantlist, Fragment1).commit();
} else {
String id = String.valueOf(getIntent().getExtras().getString(
"restaurant_id"));
fragmentManager.beginTransaction()
.replace(R.id.offerlist, Fragment2).commit();
}
Now how do i move to Fragment 3 by clicking a list item on Fragment 2?
Right now, im also using putEctra AND getExtra "id". For Fragment 2 and Fragment 3. But how do i use it to differentiate inside the above code?

Your question is not clear enough for me. If i get you right you have 3 fragments and there is a situation you want to show them all at the same time (e.g. in tablets). If that is not the case don't use fragments at least the way you are using it right now, Instead use another activity because using fragments where there is no need for them only makes your application more complicated.
Any way i suppose you have 3 container in your activity. when app starts add them all! . also add a onItemClike listener to fragment 1, and fragment 2. so when ever a click on item happens you now about that. Now whenever a click happens inform the other fragment to show the relevant item. to do that you only need to define a public method in fragment 2 and fragment 3.
you can also use fragment manager show() and hide() methods to hide your fragment when necessary.

Related

Load Fragment only when Tab clicked

I want my fragment to load only when the tab is clicked. That is I am calling a webservice on each fragment, so I want that webservice to be called only when user clicks the specific tab; loads the fragment.
My Fragments are attached to the view pager.
I have override the following method in my fragments: setUserVisibleHint
override fun setUserVisibleHint(isFragmentVisible: Boolean) {
super.setUserVisibleHint(true)
if (this.isVisible) {
// we check that the fragment is becoming visible
if (isFragmentVisible && !isLoadOnce) {
callAPI(param)
isLoadOnce = true
}
}
}
the variable is set as: private var isLoadOnce = false in the fragment class.
I have 3 fragments in number the problem is when my activity popsup, the first fragment is visible and if I click the last tab that is the third tab to load the third fragment, nothing happens that is the web service won't call at all.
But when I click the second fragment and then the third fragment, and yes the webservice then only calls
So I want to call the web service whenver the user clicks each fragment (number 2 fragment or number 3 fragment)!
Can somebody please figure out what I am doing wrong?
I think there are at least 2 solutions to your problem:
Call "callApi(param)" on onResume() of the fragment;
Override onPageSelected(int) and call "callApi(param) in it.
Let me know if this worked for you!
viewpager generally loads the side views to provide smooth swipe experience.
you can restrict the viewpager to load the view using
viewpager.setOffScreenLimit(0)

Call Fragments onCreateView in context with Tabs

I have 2 Tabs and 2 Corresponding Fragments. On calling the LAUNCH Activity both Tabs were added and then the first one added will be shown. Thus the first Fragments onCreateView is called the second Fragments ones not.
In my case this is an issue because the first Fragment has to call methods on the second Fragment. Inside the second Fragment there is an Objectreference which will be set by calling the onCreateView in the second Fragment.
Therefore I used following code snippet to solve this
actionBar.setSelectedNavigationItem(1);
actionBar.setSelectedNavigationItem(0);
It works but in my opinion there must be another possibility to solve this issue. Like calling the onCreateView of the second Fragment?
Here is the relevant code snippet. The listener is implemented as in android-dev Sample only with small changes not affecting my issue.
simplexFragment corresponds to the first Fragment
graphicFragment corresponds to the second Fragment
// adds two tabs
actionBar.addTab(actionBar.newTab().setText("Input").setTabListener(new TabListener(null, "input_fragment")));
graphicFragment = new GraphicFragment();
actionBar.addTab(actionBar.newTab().setText("Graphic").setTabListener(new TabListener(graphicFragment, "graphic_fragment")));
simplexFragment.setGraphics(graphicFragment); // sets the internal reference!
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
// selects the Tab so the GraphicFragments onCreateView will be called
actionBar.setSelectedNavigationItem(1);
actionBar.setSelectedNavigationItem(0);
Thanks for support.
In my case this is an issue because the first Fragment has to call methods on the second Fragment.
This is not how Fragments are meant to work. The idea is a Fragment should be self-contained and re-usable and one Fragment shouldn't know that another exists (or at least shouldn't rely the existence any other Fragment).
For example, suppose you have 3 Fragments and ActivityA uses FragmentA and FragmentB but you have another Activity (ActivityB) which uses FragmentA and FragmentC. In that case, FragmentA doesn't know what the other Fragment is (B or C) and shouldn't even expect there to be another Fragment at all.
The way to achieve what you want is to use callback methods on the Activity and have it perform the actions on any other Fragments (if they exist). It can do this by either calling public methods on the other Fragments or by passing data in the 'arguments' Bundle when it creates the other Fragments.

FragmentManager - not able to access the fragment in another activity

I have two fragments like left panel one fragment and right side another fragment having.
The left panel fragment i having the add button from there when i click add button it launches another activity, from this activity i am trying the access the fragment but i am not getting.
This is the code i am using in my activity
LeftFragment left = (LeftFragment) getFragmentManager().findFragmentById(R.id.fragment1);
finish();
Can anyone help me.
Well, this because you can't get access to FragmentManager of other Activity, and it`s absolutely normal.
You can simply commit second fragment to the same container as a first one (use single Activity) and use method setCustomAnimations(...) for your transaction to animation.
Good luck!
you can define another ListFragment in your Fragment like this:
SecondListFragment SecondListFragment= (SecondListFragment )getFragmentManager().findFragmentById(R.id.second_list_fragment);
SecondListFragment.SetupSecondFragmentList();//its written on onListItemClick in FirstFragment
SetupSecondFragmentList() is a function that setup a list view in my Second ListFragment which has called from first one

How to keep only first added Fragment in back stack (fragment overlapping)?

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.

FragmentManager.popBackStack() does not simply loads the previous Fragment

I have a main TabActivity which has two tabs, A and B (for now). Tab A loads a FragmentActivity (code given below) which just conatains a FrameLayout, so I can load my Fragments for that specific Tab in it.
The first Fragment has some TextViews and one ListView. Data is pulled from a web service. When I click on an ListView's item, I load that item's detail in another Fragment (this also comes from a web service) and replace the current Fragment (with ListView and other controls) with another detail fragment.
To achieve this, I am using android-support-v4.jar library to use Fragments as they were preferred.
Tab A's FragmentActivity's XML:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<FrameLayout
android:id="#+id/updates_frame"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#drawable/background"/>
</LinearLayout>
Tab A's FragmentActivity Java code:
public class UpdatesFragmentActivity extends FragmentActivity implements
IUpdateNotifier {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.updates);
//Load Initial Fragment into FrameLayout
//I am adding this Fragment to BackStack
Fragment newFragment = new UpdatesFragment();
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.addToBackStack(null);
ft.add(R.id.updates_frame, newFragment);
ft.commit();
}
//This is an Interface method which I call with the clicked "FEED" object to load its detail in another Fragment
#Override
public void onFeedSelected(Feed feed) {
// Instantiate a new fragment.
Fragment newFragment = new FeedDetailFragment(feed);
// Add the fragment to the activity, pushing this transaction
// on to the back stack.
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.replace(R.id.updates_frame, newFragment);
ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
ft.addToBackStack(null);
ft.commit();
}
//This is another Interface Method which I call when the user presses "BACK".
//I am trying to load the previously loaded Fragment, which I added to BackStack.
//But this causes reconstruction of the previously loaded fragment. LIST in this case
//which call the web service. I DONT WANT TO CALL SERVICE AGAIN.
#Override
public void onBackPressed() {
FragmentManager fm = getSupportFragmentManager();
if (fm.getBackStackEntryCount() > 0) {
fm.popBackStack();
}
}
}
I have created an interface IUpdateNotifier, which contains two methods:
public void onFeedSelected(Feed feed);
public void onBackPressed();
Parent UpdatesFragmentActivity implements these methods. I call these methods from children Fragments upon following actions.
I call onFeedSelected(Feed feed) from the Fragment which has a ListView. I send the clicked feed item to parent FragmentActivity, so it loads another Fragment which would contain that feed detail.
I call onBackPressed() from the second feed detail Fragment when the user presses a button that is supposed to bring back the first fragment which contained ListView with other controls. As you can see, I try to call FragmentManager's popBackStack() method to bring back that first Fragment...
But the first Fragment gets refreshed and loads all the data from web service.
Actually I cannot get and store data only once nor the updates are frequent on some time intervals. The user can update the list when he wants. Initially, the list loads the top 10 items from the service, and then user can click the "More" button at the end of list if he wants to load more items.
It will load the next 10 items and so on. But I think I can store the retrieved ArrayList in some variable in UpdatesFragmentActivity and then just reassign that ArrayList to the list's adapter instead of loading the data from service, but I don't know how to make Fragment not to call service again.
I want it to behave like when I click on tab 2 and then on tab 1 again. It simply shows the loaded data as if was hidden and does not call the service.
How can I achieve this?
Your design pattern is flawed due to a poor separation of concerns. The updating of data should be decoupled from the UI, therfore when a user goes back to the previous Fragment it should have nothing to do with loading data from a web service.
There are a couple of easy fixes but I do not know what will work best as you have given little context to the problem.
First option would be to introduce a Splash Screen on start up. This Activity would make use of an AsyncTask to download the data you need from the web service. This works well if you only want the data to be downloaded once during the runtime of the app. You would make sure not to add this Activity to the history so when back is pressed from the next activity, the app would then exit.
Another option, which I have used in many apps and the one I prefer, is the use of Alarms via the AlarmManager. You can set a periodic updates at specific time intervals, the AlarmManager even helps you to the point where it contains enumerations of time. The Alarm will trigger a broadcast receiver which will execute your custom code, that will download the data you need from the web service and store it.
There is a tutorial on this approach, which can be found here http://android.arnodenhond.com/tutorials/alarm-notification.
Finally; you should not need to pop the back stack to get around this problem, although you might be doing this for entirely different reasons but it is hard to tell without more info.
Your question is not clear enough, ask more simple and precise questions... And as you say above
popBackStack does not load the last fragment, it's commonly used to pop the entire stack :
fragmentManager.popBackStack(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);
before loading another fragment
beginTransaction()
replace() Or add()
commit()
That's all i can think about with that question
Good luck

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