Develop Reference

Restore activity with the right fragment and state

I have an application with a main menu that when clicked, navigate to different activities.
One of these activities its a Search, with container that i update with many fragments. Its a kind of search, with 3 steps. (Step 1, Step 2, Step 3)
When i go for other activity and back to the Search Activity, the state is lost.
Whats is the best way to restore the activity with the right fragment ?
I have tried android:launchMode="singleInstance" and also intent.addFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT or Intent.FLAG_ACTIVITY_CLEAR_TOP) to force one instance of activity, and actually works but is taking time to open the activity for the first time (the app kind of stop works and then start again)
I think i can't just use savedInstanceState() because, each fragment need some information chosen on the previous fragment
Any suggestion ?
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android">
<!--Top bar Menu-->
<include layout="#layout/partials_top_bar"/>
<FrameLayout
android:windowSoftInputMode="adjustNothing"
android:id="#+id/container"
android:layout_weight="1"
android:layout_width="match_parent"
android:layout_height="wrap_content">
</FrameLayout>
<!--Bottom Bar Menu-->
<include layout="#layout/partials_bottom_bar"/>
</LinearLayout>
When the user choose some action, them i update the actual fragment with
activity.supportFragmentManager
.beginTransaction()
.replace(R.id.container, fragment)
.addToBackStack(null)
.commit()
EDIT: Found a solution. The "delay" / App freeze showed when i open SingleInstance was caused by removing the transition animation of all activities. But only the single instance activity presents this delay. So i'm gonna use this. Thank you so much guys.

You can create a static variable "state" in your activity, could be String, and when you change Fragment, you change de variable value, for example, when you change to the StepOneFragment you put the value to
"step_one", StepTwoFragment -> "step_two", StepThreeFragment -> "step_three", and if you get back you change the variable value depending in what fragment are you on, then in onCreate of SearchActivity, you make a switch in that variable, and depending of the value, you load the desired Fragment.
Hope it helps

How to switch from Surface View (running in an activity) to other activity

In one of scenario, I have implemented Surface View which is part of an Activity. Now I need to hide this Video view so can roam in other screen of application.
AFAIK, we can't minimise/hide Activity, what could be other approach to handle such scenario.
I come across Hangout & WhatsApp Video calling scenario, they hide video view while move back to other activity & resume when need.
I also come across Youtube mobile application, but they might be managing everything in single activity. Also found some solution available here. & here. I still need to try.
How they do. Any suggestion !

Simple answer: Don't keep a view alive between activities. You can save and pass states/variables, but it is not smart to keep it in memory. So either :
Switch to a fragment structure and create a fragment containing the SurfaceView attached to a View and move it to the background when not needed
Or keep an instance (or the states) of the surfaceview and detach it from the attached View and reattach it when needed
I think these are the only legit ways to go for. I once did this just using a Singleton for the surfaceview and attaching/detaching it from a view when needed, but this is not the cleanest way.
Comment Pseudo code transaction
You should have the following: An Activity, FragmentA, FragmentB and VideoFragment. The Activity layout only consists about two viewholders, one that is full screen (for FragmentA and B) and the other one that is for the video view. To create fragments just right click New->Fragment->Blank. First you'll have to init the fragment in the view to do this and eventually replace FragmentA with FragmentB you could use the following code:
Fragment fragmentB = new FragmentB();
FragmentManager fm = getSupportFragmentManager();
FragmentTransaction transaction = fm.beginTransaction();
transaction.replace(R.id.viewHolder, fragmentB);
transaction.commit();
Your activity layout should look something like this:
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:context="nl.coffeeit.clearvoxnexxt.activities.TestActivity">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent" >
<FrameLayout
android:id="#+id/viewHolderFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#F00"/>
<FrameLayout
android:id="#+id/videoHolder"
android:layout_width="300dp"
android:layout_height="200dp"
android:layout_alignParentBottom="true"
android:layout_alignParentRight="true"
android:layout_margin="16dp"
android:alpha="0.5"
android:background="#00F"/>
</RelativeLayout>
</android.support.design.widget.CoordinatorLayout>

Android Fragment for tablets and phone

I want to do something like that. An picture is easier than words:
And when the user clicks on a button on the Fragment B, the fragment B changed but not the A.
I've made two different layout (A portrait and a land one). The first one has a layout like
<?xml version="1.0" encoding="utf-8"?>
<fragment
xmlns:android="http://schemas.android.com/apk/res/android"
android:name="com.my.app.ContactsFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/contacts_fragment" />
I've a button in my fragment layout with a simple activity call:
Intent intent = new Intent(getActivity(), NextActivity.class);
startActivity(intent);
And the land one is like that:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="match_parent">
<fragment
xmlns:android="http://schemas.android.com/apk/res/android"
android:name="com.my.app.ContactsFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/contacts_fragment" />
<fragment
xmlns:android="http://schemas.android.com/apk/res/android"
android:name="com.my.app.HomeFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/fragment_container" />
</LinearLayout>
I change the inner fragment using the following code:
FragmentTransaction ft = getActivity().getFragmentManager().beginTransaction();
NextFragment nextFrag = new NextFragment();
ft.replace(R.id.fragment_container, nextFrag);
ft.addToBackStack(null);
ft.commit();
This part works well.
I have two questions now:
How to put these two ways to change the content in the main activity? I mean, in the main activity, a fragment should call the second way, but in a normal activity, I need to call the first.
If I click on an item in the fragment A, and then I click on the button in fragment B that changes the fragment to NextFragment. If I click on another item and i do the same. I can go back to the first user. Is there a way to dump the stack when clicking on a new item ?
Thanks for your help.
Ps: I'm using the native fragment lib not the support v4.

I'm struggling to understand the specifics of your 2 questions, as they are vague and do not give enough detail.
However, since you want your Fragments to be changed out at runtime, you should not put <fragment/> in your layout files. Your current architecture makes it impossible to change out the Fragments in your layouts, which is not what you want.
Note: When you add a fragment to an activity layout by defining the fragment in the layout XML file, you cannot remove the fragment at runtime. If you plan to swap your fragments in and out during user interaction, you must add the fragment to the activity when the activity first starts.
You should be using FrameLayout containers for your Fragments in your layout files, and have a single Activity add Fragments to those FrameLayout containers depending on if they are there. This will allow the app to create 1 Fragment in portrait and 2 Fragments in landscape (given you have have a layout for each orientation). This will also allow you to be able to swap out Fragments as your please, and add them to the back stack.
And example of this Google recommended approach can be found here.

You can find a good solution from here.

Complex Android UI design guidance needed (fragments)

I am developing an applications that is aimed at Tablets and Google TVs. It will be like many standard Google TV applications with a LeftNavBar and a top Search bar that is common to all application screens. It will look something like the following image:
Main Screen
The RED area will be different for all other screens. It may contain data like following screens mockups:
Activity One loaded into main container
Activity Two loaded into main container
So you can see that completely different sections can be loaded in the main area.
Screen 3 can be loaded as a detailed section when selecting any list item in Screen 2 (say in fragment list) OR it can be loaded as a result of selecting a tab (which will appear in LeftNavBar).
Here is how I am trying to implement it.
Step 1. I Created a main Activity with the following XML:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<LinearLayout
android:layout_width="match_parent"
android:layout_height="50dp"
android:background="#9ccc" >
<!-- Top Bar -->
</LinearLayout>
<FrameLayout
android:id="#+id/mainContainer"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1">
<!-- main Red Container that will load other Activities -->
</FrameLayout>
</LinearLayout>
mainContainer is the RED container where I want to load the Activities. LeftNavBar will be added to this Activity as its the parent of All.
Step 2 I created ActivityOne & ActivityTwo with two & three Fragments in them respectively (as shown in above second & third image).
*Step 3 I am trying to load the ActivityOne in main page's mainContainer FrameLayout... But I cannot add it.
I tried by adding the ActivityOne to mainContainer as follows:
View v = (new ActivityOne()).getWindow().getDecorView();
FrameLayout mainContainer = (FrameLayout) findViewById(R.id.mainContainer);
mainContainer.addView(v);
but the getWindow() returns null....
Other issue occurs because all the data comes from a remote services .. so please also suggest how would I be able to hold references to all the loaded Activities in mainContainer in a some kind of stack ... so I can just reload the already loaded activity instead of creating its new instance.. This will be used on BACK button press.
OR
Instead of loading an activity into the above RED container, I should create two Activities each with their own Fragments & a LeftNavBar. This might be easier than the aforementioned approach. or this might be the only solution.... however I feel that saving state for BACK buttons might get messy .. but I will try implementing this
What would you do if you had to create this type of application?
How would you design the UI layout for best performance/practice?
Your suggestions in helping me setting this app's layout are much appreciated.

Disclaimer
This is where fragments can get tricky. The problem would be simple if Activity 1 & 2 had identical layouts so that you could simply attach/detach fragments and use the fragment back stack to unwind.
Because you want 2 unique layouts to house your fragments, things are going to be a little more involved. If at all possible I would try to use the same layout so that you can take the easy path.
As another option, you could use two activities as you outline above and send data back and forth with Intents.
That said, if I really had to implement this solution as written, here is what I would do. Note that I am not advocating this solution but myself do not know of a better way of doing things.
The Solution
Create a FragmentActivity whose view would be Main Screen as you've defined above. The layout for the Main Screen would contain:
Left nav bar
Top bar
2 layouts. layout1 and layout2. These would be contained in a parent layout i.e. RelativeLayout or LinearLayout and would contain the necessary FrameLayout elements for your fragments.
Example using your XML (note, tags are a bit brief):
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<LinearLayout
android:layout_width="match_parent"
android:layout_height="50dp"
android:background="#9ccc" >
<!-- Top Bar -->
</LinearLayout>
<LinearLayout android:id="#+id/layout1">
<FrameLayout android:id="#+id/listFragment" />
<FrameLayout android:id="#+id/contentFragment" />
</LinearLayout>
<LinearLayout android:id="#+id/layout2">
<FrameLayout android:id="#+id/imageFragment" />
<FrameLayout android:id="#+id/boxFragment1" />
<FrameLayout android:id="#+id/boxFragment2" />
<FrameLayout android:id="#+id/boxFragment3" />
</LinearLayout>
</LinearLayout>
The main idea is that you then show/hide layout1 & layout2 i.e. set android:visibility="gone" based on the state of your app.
The disadvantages of this method are:
Using fragment backstack may be impossible, instead you'll have to track where the user is in your UI flow and manage the back button to show/hide layout
You may need to take special care to attach/detach fragments when you show/hide their parent view to reduce resource consumption while the fragments are invisible
The advantages are:
Easy communication between fragments and the base activity since only 1 activity is used

Re: The nested Fragments problem
To get around the 'nested Fragments' problem in our application where (as you correctly note) Fragments cannot add Fragments I hosted a single templating Fragment under the activity whose only purpose was to define a set of place holders for other fragments to anchor to. When adding further Fragments to the activity past this point I used the templating Fragment's view place holder +#ids to identify the "root" or parent view Id for the Fragment being added.
getSupportFragmentManager().beginTransaction().add(#someIdFromTheTemplateFrag, fragment, fragmentTag).commit();
The Fragment I was adding then knew where to anchor itself in the current layout and of course then went about it's merry way of add it's view. This had the effect of attaching a Fragment to another Fragment hence achieving the desired visual 'nesting'...

How can I use Fragments to create layout in the image displayed

Here is the image screenshot:
My query is how can I implement the Stack layout shown? I have scoured the resource files and most only show how to implement two fragments.
Would anyone please give me any example of how I can create the Stack fragment as shown?
Will appreciate it. Thanks.

If your fragments are closely tied together, just don't run them in separate activities. For the single pane case you can just switch fragments within one activity.
Otherwise, if you do want to separate them between activities, you need to use the onActivityResult() model for propagating results back, and in the dual-pane case "emulate" it by just having the second call onActivityResult() of the first fragment. Note that Fragment.setTargetFragment() includes a request code argument to facilitate this.
I have activity A loading Fragment F1 which loads fragment F2
IMHO, fragments should not load other fragments. Activities load fragments, based upon available screen space. Fragments should neither know nor care whether any other fragment exists in the current activity, or if other fragments are in other activities.
I have F2 calling back to activity A to pop it off of the stack. Should I then be looking at passing a message to F1 to do what it needs to do?
Yes.
What I'm wondering is whether I'm on the right track with regards passing messages back and forwards via the parent activity or is there a more direct way of F1 responding to F2 performing something that requires it to be closed and F1 do what it needs to do.
I would not have F1 even know that F2 exists, or vice versa. When the user does something in F1 that should result in a major context shift (e.g., display some other fragment/activity), F1 should let the hosting activity know, perhaps via a listener interface registered with F1 (to support multiple possible hosting activities). The activity would then arrange for F2 to appear, either in its own activity or in another activity. Similarly, when F2 wraps up, it would let its hosting activity know via a listener interface, and that activity can route control back to the appropriate spot.
I am somewhat skeptical of your whole "F2 performs an action which should result in it being closed" approach, unless F2 is a DialogFragment.

One possible solution is given below
Please tweak width and heights according to the use case
For Landscape use
<LinearLayout android:orientation="horizontal" ..>
<fragment android:name="com.example.FragmentA"
android:id="#+id/fa"
android:layout_width="xdp"
android:layout_height="match_parent" />
<LinearLayout android:orientation="vertical" ...>
<fragment android:name="com.example.FragmentB"
android:id="#+id/fb"
android:layout_width="ydp"
android:layout_height="wrap_content" />
<fragment android:name="com.example.FragmentC"
android:id="#+id/fc"
android:layout_width="zdp"
android:layout_height="wrap_content" />
</LinearLayout>
</LinearLayout>
For Portrait view use
<LinearLayout android:orientation="vertical" ..>
<fragment android:name="com.example.FragmentA"
android:id="#+id/fa"
android:layout_width="match_parent"
android:layout_height="Xdp" />
<LinearLayout
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<fragment android:name="com.example.FragmentB"
android:id="#+id/fb"
android:layout_width="ydp"
android:layout_height="wrap_content" />
<fragment android:name="com.example.FragmentC"
android:id="#+id/fc"
android:layout_width="wrap_cotent"
android:layout_height="wrap_content" />
</LinearLayout>
</LinearLayout>