I would like to add a FragmentActivity in the activity layout. In order to make fragment transactions (such as add, remove, or replace a fragment), the api guides say that I first need to get an instance of FragmentTransaction from your Activity and then add a fragment using the add() method specifying the fragment to add and the view in which to insert it. Ok pretty straightforward so far, but what should I do in the FragmentActivity case?
AllEventsFragments events;
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
if ( savedInstanceState == null )
{
events = new AllEventsFragments();
FragmentTransaction transaction = getFragmentManager().beginTransaction();
transaction.add(R.id.content_frame, events,"events");
// Commit the transaction
transaction.commit();
}
}
in which AllEventsFragments is defined as follows:
public class AllEventsFragments extends FragmentActivity implements ActionBar.TabListener
{
...
}
Since the add method accepts a Fragment as second argument the error returned is:
The method add(int, Fragment, String) in the type FragmentTransaction is not applicable for the arguments (int, AllEventsFragments, String)
I would like to add a FragmentActivity in the activity layout.
You are trying to nest activities. That is not supported via fragment transactions, and what little support there ever was for it has been deprecated for ~2.5 years.
However, you can move much of the AllEventsFragments logic into a Fragment, which can then be used from both AllEventsFragments and wherever else you are trying to use it.
Related
My application has a Fragment inside its Activity. I would like to programmatically replace the fragment by another one from the current fragment itself.
For example, if I click on a button inside the fragment, the fragment should be replaced with another one, but the activity should remain the same.
Is it possible? If so, how to do it?
It's actually easy to call the activity to replace the fragment.
You need to cast getActivity():
((MyActivity) getActivity())
Then you can call methods from MyActivity, for example:
((MyActivity) getActivity()).replaceFragments(Object... params);
Of course, this assumes you have a replaceFragments() method in your activity that handles the fragment replace process.
Edit: #ismailarilik added the possible code of replaceFragments in this code with the first comment below which was written by #silva96:
The code of replaceFragments could be:
public void replaceFragments(Class fragmentClass) {
Fragment fragment = null;
try {
fragment = (Fragment) fragmentClass.newInstance();
} catch (Exception e) {
e.printStackTrace();
}
// Insert the fragment by replacing any existing fragment
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction().replace(R.id.flContent, fragment)
.commit();
}
from the official docs:
// Create new fragment and transaction
Fragment newFragment = new ExampleFragment();
FragmentTransaction transaction = getFragmentManager().beginTransaction();
// Replace whatever is in the fragment_container view with this fragment,
// and add the transaction to the back stack
transaction.replace(R.id.fragment_container, newFragment);
transaction.addToBackStack(null);
// Commit the transaction
transaction.commit();
In this example, newFragment replaces whatever fragment (if any) is currently in the layout container identified by the R.id.fragment_container ID. By calling addToBackStack(), the replaced fragment is saved to the back stack so the user can reverse the transaction and bring back the previous fragment by pressing the Back button.
The behavior you have described is exactly what fragments are designed to do. Please go through the official guide for a thorough understanding of fragments which will clear up all your questions.
http://developer.android.com/guide/components/fragments.html
Please note that fragment should NOT directly replace itself or any other fragments. Fragments should be separate entities. What fragment should do is to notify its parent activity that some event has happened. But it is, again, NOT a fragment job to decide what to do with that! It should be activity to decide to i.e. replace the fragment on phone, but to i.e. add another to existing one on tablets. So you are basically doing something wrong by design.
And, as others already mentioned, your activity should use FragmentManager ("native" or from compatibility library) to do the job (like replace() or add() or remove()):
http://developer.android.com/guide/components/fragments.html
Just as Marcin said, you shouldn't have a fragment start another fragment or activity. A better way to handle this situation is by creating a callback implementation for the main activity to handle requests such as start a new fragment. Here is a great example in the android developer guide.
There is a way which works; Just (in the fragment) do the following:
getFragmentManager().beginTransaction()
.add(R.id. container_of_this_frag, new MyNewFragment())
.remove(this)
.commit();
When using nested fragments, we don't want every inner fragment replacement goes to the outer most activity. A mechanism allowing a fragment to notify its parent that it wants to change to another fragment can be useful.
Here is my code in Kotlin, I think it is easy to translate into java.
interface FragmentNavigator {
fun navigateTo(fragment: Fragment)
}
class NavigableFragment: Fragment() {
var navigator: FragmentNavigator? = null
override fun onDetach() {
super.onDetach()
navigator = null
}
}
Inner fragments need to extend NavigableFragment, and use following code to change itself to another fragment.
navigator?.navigateTo(anotherFragment)
Outer activities or fragments need to implement FragmentNavigator, and override navigateTo.
override fun navigateTo(fragment: Fragment) {
supportFragmentManager.beginTransaction().replace(view_id, fragment).commit()
}
//Use childFragmentManager instead of supportFragmentManager a fragment
Finally in outer activities or fragments, override onAttachFragment
override fun onAttachFragment(fragment: Fragment?) {
super.onAttachFragment(fragment)
if(fragment is NavigableFragment) {
fragment.navigator = this
}
}
This worked for me:
getActivity().getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,
new MenuFragment()).commit();
For Kotlin.
(activity as YourActivityLauncherFragment)
.supportFragmentManager.beginTransaction()
.replace(R.id.yourFragmentContainer, YourFragmentName()).setReorderingAllowed(true)
.commit()
Hi i created a project with a default "Navigation Drawer Activity".
So i have a MainActivity with a fragment with is replaced for each item on menu.
One of the menus is "Customers" with shows a list of customers.
From customers fragment i can see the Interests of this customers, with is a Fragment(CustomerListFragment) calling the interests(InterestsListFragment).
There is even more levels, but to be short that's enough.
This is the code on MainActivity that i use to call fragment from fragment and pass data between
public void passData(Object[] data, Fragment f) {
Bundle args = new Bundle();
args.putSerializable("PASSED_DATA", data);
f.setArguments(args);
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction()
.replace(R.id.container, f)
.addToBackStack("")
.commit();
}
And i use like :
mCallbacks.passData(new Object[]{c}, new OpportunityListFragment());
The problem is that when i rotate the phone does not matter from wich level of activity i have, it comes back to the first fragment called(CustomerListFragment), and if i click "Back" on cellphone it gets back to where i was when i rotate the phone.
What do i have to do, to avoid this kind of problem? why it gets back to the first activity evoked if i am replacing fragments?
The answer from ste-fu is correct but let's explore programmatically. There is a good working code in Google documentation # Handling Runtime Changes. There are 2 code snippets that you have to do.
1) Code snippet:
public class MyActivity extends Activity {
private RetainedFragment dataFragment;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// find the retained fragment on activity restarts
FragmentManager fm = getFragmentManager();
dataFragment = (DataFragment) fm.findFragmentByTag(“data”);
// create the fragment and data the first time
if (dataFragment == null) {
Note: Code uses FragmentManager to find the current Fragment. If fragment is null, then the UI or app has not been executed. if not null, then you can get data from RetainedFragment object.
2) Need to retain the Fragment state.
public class RetainedFragment extends Fragment {
// data object we want to retain
private MyDataObject data;
// this method is only called once for this fragment
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// retain this fragment
setRetainInstance(true);
}
Note: setRetainInstance is used in OnCreate. And subclassing the Fragment is recommended, naming it RetainedFragment, used on snippet 1.
When you change screen orientation your parent Activity is destroyed and recreated. Unless you persist the level structure in some fashion, it will always appear as when you first started the activity. You can either use the bundle object, or for more complicated objects you need to persist it to a database.
Either way, onSaveInstanceState is your friend. Then in your onCreate method you need to check the bundle or database, and the set the fragment accordingly.
I have this Activity which at first shows a Fragment with a list of elements. This works perfectly with this code:
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.list_act);
if(null == savedInstanceState)
{
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
ListFragment glfragment = new ListFragment();
fragmentTransaction.add(R.id.listfrag1, glfragment);
fragmentTransaction.commit();
}
}
Well I have a ListFragment and a DetailFragment. But I don't know how to do the transition when I click an element of the list. I know the fragmentTransaction.replace(), but I don't know WHEN to call it.
I thought I should use the OnListItemClick() inside the ListFragment, but I don't know how to use the FragmentManager inside the Fragment and not in the main Activity... Also I want to "export" some data to the DetailFragment as if it was a Intent, but it's not.
To use the fragment manager inside your Fragment, simply call
getActivity().getFragmentManager() instead of getFragmentManager(). Implementing this in your OnItemClickListener should suffice.
What I would do is:
Define an interface with one method listItemSelected() with as an argument the id of the selected item
Let your activity implement this interface
In the onAttach of your list fragment, take the activity and keep it as a member variable, cast to the interface type. Make sure that in the onDetach you dereference it.
In your onListItemClick, call this method on your activity
In the activity, you can now do a new fragmenttransaction, this time you need to replace instead of add the fragment
To create your detail fragment with the correct argument (the id), use the method described here.
This should normally work fine.
The main fragment activity in my application has the following function
private final void insertFragmentIntoView(final SherlockFragment fragment,
String tag) {
FragmentManager fm = getSupportFragmentManager();
FragmentTransaction ft = fm.beginTransaction();
ft.add(R.id.fragment_content, fragment, tag);
ft.commit();
}
The R.id.fragment_content is a frame layout and i basically insert a new fragment into this frame. Now the frame that i insert has a button that should take me onto a new screen. What i want is that all navaigation in my application should take place in my FragmentActivity. How can i call my FragmentActivity from with a child fragment ?
Kind Regards
Make a listener class in your fragment and your parent activity will implement that listener .
Now register listener in your fragment and call method in which you want to perform some action.
More you can see this link http://developer.android.com/training/basics/fragments/communicating.html
Example how fragment and activity communicate.
class MyFragment extends Fragment{
class interface MyFragmentListener {
doSomeAction();
}
MyFragmentListener myListener;
onAttach(){
myListener=(MainActivity )getActivity();
}
onButtonClick(){
myListener.doSomeAction();
}
}
class MainActivity extends FragmentActivity implements MyFragment.MyFragmentListener
{
doSomeAction(){
//TODO perform some action from your fragment to activity
}
}
Using listeners is the recommended way of communicating between Fragment and your activity.
See this Android documentation section for infromation. Long story short they just implement a listener interface by the Activity class and cast getActivity() result in a fragment to a listener.
From my personal experience this is very convenient because lets you to:
Easilly switch underlying activity (e.g. you host entire fragment in a wrapper activity for compatibility in pre-3.0 and host this fragment along with others in 11+)
Easilly control if the wrapper activity supports callbacks or not. Just check is it does implement the listener and do your app specific actions if it doesn't.
My application has a Fragment inside its Activity. I would like to programmatically replace the fragment by another one from the current fragment itself.
For example, if I click on a button inside the fragment, the fragment should be replaced with another one, but the activity should remain the same.
Is it possible? If so, how to do it?
It's actually easy to call the activity to replace the fragment.
You need to cast getActivity():
((MyActivity) getActivity())
Then you can call methods from MyActivity, for example:
((MyActivity) getActivity()).replaceFragments(Object... params);
Of course, this assumes you have a replaceFragments() method in your activity that handles the fragment replace process.
Edit: #ismailarilik added the possible code of replaceFragments in this code with the first comment below which was written by #silva96:
The code of replaceFragments could be:
public void replaceFragments(Class fragmentClass) {
Fragment fragment = null;
try {
fragment = (Fragment) fragmentClass.newInstance();
} catch (Exception e) {
e.printStackTrace();
}
// Insert the fragment by replacing any existing fragment
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction().replace(R.id.flContent, fragment)
.commit();
}
from the official docs:
// Create new fragment and transaction
Fragment newFragment = new ExampleFragment();
FragmentTransaction transaction = getFragmentManager().beginTransaction();
// Replace whatever is in the fragment_container view with this fragment,
// and add the transaction to the back stack
transaction.replace(R.id.fragment_container, newFragment);
transaction.addToBackStack(null);
// Commit the transaction
transaction.commit();
In this example, newFragment replaces whatever fragment (if any) is currently in the layout container identified by the R.id.fragment_container ID. By calling addToBackStack(), the replaced fragment is saved to the back stack so the user can reverse the transaction and bring back the previous fragment by pressing the Back button.
The behavior you have described is exactly what fragments are designed to do. Please go through the official guide for a thorough understanding of fragments which will clear up all your questions.
http://developer.android.com/guide/components/fragments.html
Please note that fragment should NOT directly replace itself or any other fragments. Fragments should be separate entities. What fragment should do is to notify its parent activity that some event has happened. But it is, again, NOT a fragment job to decide what to do with that! It should be activity to decide to i.e. replace the fragment on phone, but to i.e. add another to existing one on tablets. So you are basically doing something wrong by design.
And, as others already mentioned, your activity should use FragmentManager ("native" or from compatibility library) to do the job (like replace() or add() or remove()):
http://developer.android.com/guide/components/fragments.html
Just as Marcin said, you shouldn't have a fragment start another fragment or activity. A better way to handle this situation is by creating a callback implementation for the main activity to handle requests such as start a new fragment. Here is a great example in the android developer guide.
There is a way which works; Just (in the fragment) do the following:
getFragmentManager().beginTransaction()
.add(R.id. container_of_this_frag, new MyNewFragment())
.remove(this)
.commit();
When using nested fragments, we don't want every inner fragment replacement goes to the outer most activity. A mechanism allowing a fragment to notify its parent that it wants to change to another fragment can be useful.
Here is my code in Kotlin, I think it is easy to translate into java.
interface FragmentNavigator {
fun navigateTo(fragment: Fragment)
}
class NavigableFragment: Fragment() {
var navigator: FragmentNavigator? = null
override fun onDetach() {
super.onDetach()
navigator = null
}
}
Inner fragments need to extend NavigableFragment, and use following code to change itself to another fragment.
navigator?.navigateTo(anotherFragment)
Outer activities or fragments need to implement FragmentNavigator, and override navigateTo.
override fun navigateTo(fragment: Fragment) {
supportFragmentManager.beginTransaction().replace(view_id, fragment).commit()
}
//Use childFragmentManager instead of supportFragmentManager a fragment
Finally in outer activities or fragments, override onAttachFragment
override fun onAttachFragment(fragment: Fragment?) {
super.onAttachFragment(fragment)
if(fragment is NavigableFragment) {
fragment.navigator = this
}
}
This worked for me:
getActivity().getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,
new MenuFragment()).commit();
For Kotlin.
(activity as YourActivityLauncherFragment)
.supportFragmentManager.beginTransaction()
.replace(R.id.yourFragmentContainer, YourFragmentName()).setReorderingAllowed(true)
.commit()