I am trying to build an app with one MainActivity and multiple fragments.
In my MainActivity, I get the data and store it in the Data Model.
For example, getting sunrise time, then display it in Fragment B.
How can I detect the sunrise value changes and update the TextView in Fragment without restarting the app? Is there way can listen to value changed and update the textView?
here are my codes and fragment B layout.
JAVA data model CLASS
public class SunriseTimeClass {
private static final SunriseTimeClass INSTANCE = new SunriseTimeClass();
public String sunrise = "";
private SunriseTimeClass(){ }
public static SunriseTimeClass getInstance(){
return INSTANCE;
}
}
MAINACTIVITY
override fun onCreate(savedInstanceState: Bundle?) {
//this will clear the back stack and displays no animation on the screen
var sunRise = SunriseTimeClass.getInstance()
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
setSupportActionBar(toolbar)
supportActionBar!!.setDisplayShowHomeEnabled(true)
getSunriseSunset()
}
fun getSunriseSunset(){
val location = com.luckycatlabs.sunrisesunset.dto.Location("40.9167654", "-74.171811")
val calculator = SunriseSunsetCalculator(location, "America/New_York")
sunRise.sunrise = calculator.getOfficialSunriseForDate(Calendar.getInstance())
}
FRAGMENT B layout
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center">
<TextView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:text=""
android:gravity="center"
android:id="#+id/DisplaySunrise"/>
</FrameLayout>
(Java code)
Create a setter method in fragment which will be called by activity like:
In fragment:
public void setSunrise(String sunrise){
this.sunrise = sunrise;
//further operations..
}
And in Activity:
Fragment fragment = new Fragment(); //your fragment
String s= calculator.getOfficialSunriseForDate(Calendar.getInstance());
fragment.setSunrise(s);
If I understood you right, you need change/update the fragment when something happens in the Activity.
So I think you could implement an interface ( callback ) between the Activity and the Fragment.
1.You need create an interface in the Activity:
public interface OnActivityAction {
void updateFragment();}
2.You need declare the interface and the setter in the Activity and call it when you want
public OnActivityAction actionListener;
public void setOnActionListener(OnActivityAction fragmentListener) {
this.actionListener = fragmentListener;
}
private void myActionToUpdate(){
if (null != activityListener) {
activityListener.doSomethingInFragment();
}
}
3.Then in your Fragment need implement this interface and set the listener.
public class MyFragment extends Fragment implements OnActivityAction {
#Nullable
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
super.onCreateView(inflater, container, savedInstanceState);
View rootView = inflater.inflate(R.layout.fragment_test_two, container, false);
((MainActivity) getActivity()).setOnActionListener(this);
return rootView;
}
#Override
public void updateFragment() {
//Do whatever you want
}
}
I hope this helps you.
Add fragment from activity
FragmentManager fragmentManager = getSupportFragmentManager();
android.support.v4.app.FragmentTransaction fragmentTransaction =
fragmentManager.beginTransaction();
//frame_layout put in activity xml
fragmentTransaction.add(R.id.frame_layout, drawer, "").commit();
Get Fragment instance and update your data
FragmentManager fragmentManager = getSupportFragmentManager();
Fragment fragment = fragmentManager.findFragmentById(R.id.frame_layout);
((FragmentB)fragment).updateFragment("Updated value");
Make Public method in fragment for update textview
public void updateFragment(String value) {
//update textview here
Textview.setText(value);
}
Thanks for all the great answers.
I have used SharePreference to do my job. working as expected.
There are two possible ways to approach this.
FragmentB gets the sunRise data and updates its own TextView
Have FragmentB retrieve the sunRise values directly and update its TextView, rather than performing the retrieval in MainActivity.
OR
Communicate between Activity and Fragment via an interface
This answer is similar to another one in this thread, but is more explicit on how you would set the fragment's TextView. This solution makes several assumptions and may be an oversimplification due to the limited information in your question:
Assumption 1: This solution assumes that the getSunriseSunset method is synchronous, i.e. not dependent on any service or network call. If it is asynchronous, you would need a separate callback in your MainActivity (e.g. onSunriseRetrieved) to listen for when your data is returned, prior to updating your fragment.
Assumption 2: This solution also assumes that you want access to the fragment's views immediately after it has been added (hence, the executePendingTransactions call). That said, if you have FragmentB perform its own retrieval of the sunRise, then this assumption wouldn't be needed.
Define an interface in the Activity and :
public class MainActivity extends AppCompatActivity
{
public interface OnSunriseChangeListener
{
void onSunriseChange(String newText);
}
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState == null)
{
getFragmentManager()
.beginTransaction()
.add(R.id.fragment_container, new FragmentB()))
.commit();
//assuming you want access to the fragment's views immediately
getFragmentManager().executePendingTransactions();
}
getSunriseAndUpdateFragment(fragment);
}
/**
* Assumes that getSunriseSunset is synchronous and assumes that FragmentB is created.
*/
private void getSunriseAndUpdateFragment()
{
String newSunRiseValue = getSunriseSunset();
((FragmentB)getFragmentManager().findFragmentById(R.id.fragment_b)).onSunriseChange(newSunRiseValue);
}
// other code not shown...
}
Have FragmentB implement the interface:
public class FragmentB extends Fragment implements OnSunriseChangeListener
{
#Override
public void onSunriseChange(String newSunriseData)
{
TextView textView = getView.findViewById(R.id.DisplaySunrise);
textView.setText(newSunriseText);
}
Related
Unlike typical android projects starting with MainActivity with all the code of the layout object in it. This architecture requires me to have the initial code in a custom object. Here's a structure for better understanding.
java/MainActivity.java
java/User.java
layout/activity_main.xml
layout/user.xml
Now I also need a reference to User object within MainActivity and it looks like this.
public class MainActivity extends AppCompatActivity {
public Users users; // instantiate custom class and show
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
}
My User class looks like this.
public class User extends AppCompatActivity {
ListView userList;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.user_list, container, false); // Inflate the layout for this fragment
userList = view.findViewById(R.id.userList);
return view;
}
}
layout/user.xml
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="org.puremvc.java.demos.android.employeeadmin.view.components.UserList">
<ListView
android:id="#+id/userList"
android:layout_width="395dp"
android:layout_height="715dp"
tools:layout_editor_absoluteX="8dp"
tools:layout_editor_absoluteY="8dp" />
</FrameLayout>
So, in other words, MainActivity just acts like a stage doing nothing except just providing a reference to the Initial object. Now I do need MainActivity to be there, can't point User to be a launcher in the manifest. Responsibilities are to be taken care of by User class.
Question: How to instantiate CustomClass User and show.
Context: The MainActivity class has to be minimalistic and clean, no User related code (ListView), all logic lies in the custom class.
P.S. There can be lateral approaches, as long as I have a reference to user Object in MainActivity and it's displayed on launch, I'll accept the answer.
As per my understanding: there should be two approaches.
First, by using the Fragment inside your Activity. Write all initialize and data flow codes inside the fragment and just initialize and start the fragment from the Activity. So when the Activity will start, it will give all its tasks to the fragment with its Context and rest thing Fragment will do.
Like below:
public class MainActivity extends AppCompatActivity {
public Users users; // instantiate custom class and show
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//the fragment stuff
FragmentManager fm= getFragmentManager() //or get SupportFragmentManager when the Fragment comes from Support lib
FragmentTransaction ft= fm.beginTransaction();
Fragment fragment= new UserListFragment();
ft.add(R.id.fragment_container, fragment);
ft.commit();
}
}
OR, the second approach should by using Interface and communicate both Activity and the Custom Class (or you can call it Controller) with it.
Its nothing, but a simple MVC design pattern which I never recommend.
You can write one Interface like below:
public interface IController{
public void initialize(Activity activity, Bundle savedInstanceState);
public void engage();
public void disengage();
}
Then, make an instance of this Controller inside your Activity/BaseActivity and use like below:
public MainActivity(IController controller){
this.controller = controller;
}
Then call each callback methods from their appropriate place to make them work inside the Controller.
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//give the priviledge of onCreate to initialize
controller.initialize(this, savedInstanceState);
}
Then in your Controller class, just write the same program which you supposed to write inside Activity:
public class Your_Controller implements IController {
#Override
public void initialize(Activity activity, Bundle savedInstanceState) {
//do super where needed
//make one class level Activity instance to work in other methods
act = activity;
//just initialize views like below
TextView tv = (TextView) activity.findViewById(R.id.abc);
}
I have an activity with two fragment and want to be executed first fragment when its back from second fragment using back button. And i am using the add() when navigating first fragment to second fragment. Here is my scenario and code snippet:
First fragment:
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.one_fragment, container, false);
final Button button = (Button) view.findViewById(R.id.buttonChange);
button.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
buttonClicked(v);
}
});
return view;
}
public void buttonClicked(View view) {
FragmentManager fragmentManager = getActivity().getSupportFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.add(R.id.fragment_Container, new TwoFragment());
fragmentTransaction.addToBackStack("sdfsf");
fragmentTransaction.commit();
}
Moving to Second fragment and here is the code:
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.two_fragment, container, false);
return view;
}
The problem is that, When I am navigating from first to second fragment and then back again in the first fragment using back button first fragment lifecycle method is not executing. Instead of using add() if I use replace() then lifecycle method are executing properly. I know its the difference between add() and replace() but I want to use add() and also want to have navigation callback to handle some logic when I back in the first fragment using back button.
Also tried below code:
fragmentManager.addOnBackStackChangedListener(
new FragmentManager.OnBackStackChangedListener() {
public void onBackStackChanged() {
Log.e(TAG, "onBackStackChanged: ");
// Update your UI here.
}
});
But its also calling multiple times and creating anomalies.
How can I handle this? Specially handle some logic in first fragment when I back from second fragment.
The easiest way I can think of is to set result when you're done with the second fragment that essentially tells the first fragment to "resume" via its onActivityResult method.
When you create an instance of Fragment B, call #setTargetFragment() and pass in Fragment A as your target fragment. Then when Fragment B is done and going to return to Fragment A, before it exits, you will set the result of it for Fragment A by calling:
getTargetFragment().onActivityResult(getTargetRequestCode(), RESULT_FRAGMENT_B_FINISHED,null)
///// horizontal scroll padding
Note that RESULT_FRAGMENT_B_FINISHED would be some static integer you define somewhere, like
public static final int RESULT_FRAGMENT_B_FINISHED = 123123;
Now in Fragment A all you need to do is override onActivityResult and check that the request code matches the request code integer from setTargetFragment and the result code also matches RESULT_FRAGMENT_B_FINISHED, if so you can run the code that would have been fired from onResume().
#getTargetFragment()
#onActivityResult()
#getTargetRequestCode()
Instead of passing data between the two fragments I recommend you to use a SharedViewModel.
The idea is that the first fragment observe some data for changes and the second one edit this data.
Example:
Shared ViewModel
public class SharedViewModel extends ViewModel {
private final MutableLiveData<Item> selected = new
MutableLiveData<Item>();
public void select(Item item) {
selected.setValue(item);
}
public LiveData<Item> getSelected() {
return selected;
}
}
First fragment
public class FirstFragment extends Fragment {
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
SharedViewModel model =
ViewModelProviders.of(getActivity()).get(SharedViewModel.class);
model.getSelected().observe(this, { item ->
// Update the UI.
});
}
}
Second fragment
public class SecondFragment extends Fragment {
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
SharedViewModel model =
ViewModelProviders.of(getActivity()).get(SharedViewModel.class);
model.select(new Item("value 1","value 2");
}
}
You can read about ViewModels, LiveData and Architecture components starting from here: https://developer.android.com/topic/libraries/architecture/viewmodel#java
This answer is assuming that you want to execute some logic based on some data change. If it's not the case, you can explain what kind of logic do you want to execute and I will edit my answer.
In my project, I want to set visibility of fragments buttons from MainActivity. But the problem is, it gives NullPointerException(). I also maked listBtn & gridBtn as static. I used below code :
FirstFragment fragment = (FirstFragment)getSupportFragmentManager().findFragmentById(R.id. <frameLayout Id>);
main_page_fragment.listBtn.setVisibility(View.GONE);
main_page_fragment.gridBtn.setVisibility(View.GONE);
You cannot access to your fragment view from Activity class because activity uses its own view (ex: R.layout.activity_main). Rather you can set visibility in your corresponding fragment class which will do the same job.
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.details, container, false);
Button listBtn = (Button)view.findviewById(R.id.listBrn);
Button gridBtn = (Button)view.findviewById(R.id.gridBrn);
listBtn.setVisibility(View.GONE);
gridBtn.setVisibility(View.GONE);
return view;
}
Fragment onCreateView callback is called after onCreate method of activity, so i think you have tried to get access from it. That views will be accessible only after onResumeFragments callback is called, you should perform your actions with fragments there.
Another tip is that you strongly should not call views of fragments directly like you did or via static reference to views that's the worst. You should avoid such dependencies on fragments inner implementation. Instead of it, better is create some method like setInitialState (the name depends on your business logic) and just call it from activity.
So result code:
In activity:
private FirstFragment fragment;
protected void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//init fragment here
}
#Override
protected void onResumeFragments() {
super.onResumeFragments();
fragment.setInitialState();
}
In fragment:
//this will be called on fragment #onResume step, so views will be ready here.
public void setInitialState() {
listBtn.setVisibility(View.GONE);
gridBtn.setVisibility(View.GONE);
}
If you add your fragments dynamically from MainActivity like so:
YourFragment fragment = new YourFragment();
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction()
.replace(R.id.fragmentContainer, fragment, YOUR_TAG)
.commit();
Then you can define method in your fragment like so:
public void hideButtons()
{
yourBtn.setVisibility(View.GONE);
}
And call it from activity:
fragment.hideButtons();
I struggle with this for several hours and I found a much simpler solution.
Inside the fragment, simply make a public function (outside the on create view method) with the behavior that you want.
fun hideElement() {
binding.button.visibility = View.GONE
}
And then in main activity access to the fragment and call the function.
binding.bottomNavigation.setOnNavigationItemSelectedListener {
when (it.itemId){
R.id.someFragment -> someFragment.hideElement()
}
}
I've recently tried to use an interface for fragment-activity communication. The idea is that when a button is pressed in a fragment, it retrieves data from an EditText in the same fragment, it then sends the string to the MainActivty - this controls all my fragments - which then starts another fragment and delivers the string to this fragment for use later, however, I'm having trouble initially setting up the first interface which sends the data. Unfortunately nothing happens, and I cannot therefore get to the next fragment which should be displayed. Additionally I have tried using getActivity() but it cannot find the associated method within the fragment, leading me to believe that the fragments somehow aren't directly connected to MainActivity (I've only just grasped basics of Java and a little of Android, just learning.)
I've listed the relevant information below, thanks for the assistance!
Fragment
public class CreateWorkoutFragment extends Fragment implements OnClickListener {
View rootViewCreateWorkoutFragment;
EditText editTextWorkoutName;
// Using an ImageView for custom button
ImageView buttonNext;
String valueCreateWorkoutEditText;
OnDataPass dataPasser;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
rootViewCreateWorkoutFragment = inflater.inflate(R.layout.fragment_create_workout, container, false);
buttonNext = (ImageView) rootViewCreateWorkoutFragment.findViewById(R.id.button_workout_name_next);
editTextWorkoutName = (EditText) rootViewCreateWorkoutFragment.findViewById(R.id.edit_text_workout_name);
buttonNext.setOnClickListener(this);
return rootViewCreateWorkoutFragment;
}
public interface OnDataPass {
public void onDataPass(String data);
}
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
dataPasser = (OnDataPass) activity;
}
public void passData(String data) {
dataPasser.onDataPass(data);
}
#Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.button_workout_name_next:
valueCreateWorkoutEditText = editTextWorkoutName.getText().toString();
passData(valueCreateWorkoutEditText);
break;
}
}
}
Main Activity
public class MainActivity extends FragmentActivity implements OnClickListener, CreateWorkoutFragment.OnDataPass {
ImageView buttonCreate;
Fragment newFragment;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setTheme(R.style.AppThemeBlue);
setContentView(R.layout.activity_main);
buttonCreate = (ImageView) findViewById(R.id.create_foreground);
buttonCreate.setOnClickListener(this);
FragmentManager fragManager = getSupportFragmentManager();
FragmentTransaction tranManager = fragManager.beginTransaction();
CreateWorkoutFragment createWorkoutFrag = new CreateWorkoutFragment();
// fragment_change is just the area in XML where fragments switch
tranManager.add(R.id.fragment_change, createWorkoutFrag);
tranManager.commit();
newFragment = null;
}
#Override
public void onDataPass(String data) {
// CreateFragment is not to be confused with CreateWorkoutFragment
// CreateFragment is the fragment I'm trying to start when any strings
// are obtained from CreateWorkoutFragment
newFragment = new CreateFragment();
}
#Override
public void onClick(View v) {
switch (v.getId()) {
// create_foreground is just an ImageView used as a button
// Additionaly, other buttons are used to create other fragments,
// I've cut them out currently as they are not nessesary which is
// why CreateWorkoutFragment is only button and default currently
case R.id.create_foreground:
newFragment = new CreateWorkoutFragment();
break;
default:
newFragment = new CreateWorkoutFragment();
}
FragmentTransaction tranManager = getSupportFragmentManager().beginTransaction();
tranManager.replace(R.id.fragment_change, newFragment);
tranManager.addToBackStack(null);
tranManager.commit();
}
}
Sorry the code isn't exactly tidy, however, it was the most relevant code cut out from a large class. As I said, I have tried other methods yet cannot get any response from MainActivity either way. Thanks in advance!
Just before I posted: Got the app to write logcat messages to me, it manages to pass the data when the button is clicked - at least I think, and is something to do with the fragment not starting! At MainActivity>onDataPass()>new Fragment = new CreateFragment() Any ideas? As mentioned before, other buttons do exist and manage to change the fragment. However, were cutout to reduce amount of code posted.
getActivity() but it cannot find the associated method within the fragment
This is because getActivity() returns an Activity, not a MainActivity which is your custom subclass. You can easily fix this with a cast. For example, in your fragment, you can do this:
OnDataPass main = (OnDataPass) getActivity();
main.onDataPass(message);
Since such a cast is required, the interface seems to get in the way in my opinion. You can just as easily cast directly to MainActivity:
MainActivity main = (MainActivity) getActivity();
main.onDataPass(message);
I have a fragment which has a TextView, an EditText and a Button. I also have 2 activities which include this fragment and at onClick of the button in one of the activities, the other is started. Via the intent, the text in the edittext is passed which becomes the text of the textview of the other activity.
I had two design decisions to choose from
Create two such fragments classes with appropriate methods that construct the appropriate intents. Access the UI elements from inside the respective fragment object and start the activities.
Create only one fragment class. onClick the, event is passed down to a particular method in the activities (both the activities have this method) and the activities have the logic to build the intent and start the other activity
Consider what would happen if there are 100 such activities. The first method would have us write 100 different fragment classes with custom methods, but in the second method, it is a single class and the activities have the custom logic in a particularly named method.
Therefore I chose to go with the second choice and I realized that the UI elements could not be instantiated in the onCreate method of activity as the fragment's layout is not inflated yet. I am doing the instantiation in onStart as a workaround.
Is that bad practice or is there a better design pattern to follow?
The recommended pattern is to create a holder interface which any activity that wants to instantiate your fragment must implement. Also to set data for views in your new fragment then create a newInstance() factory method on your fragment.
I tend to approach it like this;
class FooFragment implements Fragment {
private static final String TEXT_FOR_TEXTVIEW = "textForTextView";
private FooFragmentHolder mHolder;
/*
* Rather than creating your fragment in your layout directly
* you should instead instantiate it using this class in your
* activity.
*/
public static FooFragment newInstance(String text) {
Bundle data = new Bundle();
data.putString(TEXT_FOR_TEXTVIEW, text);
FooFragment fooFragment = new FooFragment();
fooFragment.setArguments(data);
return fooFragment;
}
public interface FooFragmentHolder {
public void buttonPressed(String editTextContent);
}
/*
* When we create the fragment with the activity we use onAttach to get
* our holder implementation (the activity)
*/
#Override
public void onAttach(Activity activity) {
if (activity instanceof FooFragmentHolder) {
mHolder = (FooFragmentHolder) activity;
} else {
throw new IllegalStateException("Containing activity must implement FooFragmentHolder");
}
}
#Override
public void onCreateView(Inflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_foo, container, false);
final EditText editText = (EditText) view.findViewById(R.id.edit_text);
Button button = (Button) view.findViewById(R.id.button);
button.setOnClickListener(new OnClickListener() {
#Override
public void onClick(Button button) {
mHolder.buttonPressed(editText.getText());
}
})};
TextView textView = (TextView) view.findViewById(R.id.text_view);
Bundle args = getArguments();
if (args != null) {
textView.setText(args.getString(TEXT_FOR_TEXTVIEW));
}
return view;
}
}
Now in your activity you just need to implement the FooFragmentHolder interface and use the newInstance method we created;
class FooActivity extends Activity implements FooFragment.FooFragmentHolder {
private static final String TEXT_FOR_TEXTVIEW = "textForTextView";
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentLayout(R.layout.activity_foo);
// Instead of creating your fragment in your layout, create a holder
// layout and attach a new instance of your fragment using a fragment
// transaction.
FooFragment fooFragment = FooFragment.newInstance(getIntent().getStringExtra(TEXT_FOR_TEXTVIEW));
getFragmentManager().beginTransaction()
.replace(R.id.content, fooFragment)
.commit();
}
#Override
public void buttonPressed(String editTextContent) {
// In this case just starting the next FooActivity, but logic could be
// applied for any other activity.
Intent intent = new Intent(this, FooActivity.class)
.putExtra(TEXT_FOR_TEXTVIEW, editTextContent);
startActivity(intent);
}
}
I decided to settle with the following patter --
Any activity which includes this fragment should implement an interface like
public interface ViewsCreatedListener {
public void onViewsCreated();
}
The activity would then look like
public class ExampleActivity extends Activity implements ViewsCreatedListener {
.
.
.
.
#Override
public void onViewsCreated() {
//Initiate the views here and do what gotta be done
}
}
The fragment should check that any activity that includes this fragment should implement that interface using the onAttach method and onActivityCreated, the activity is notified
public class ExampleFragment extends Fragment {
ViewsCreatedListener listener = null;
.
.
.
.
#Override
public onAttach(Activity activity) {
super.onAttach(activity);
try {
listener = (ViewsCreatedListener) activity;
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement ViewsCreatedListener");
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
listener.onViewsCreated();
}
}
Doing this way, the fragment just provides the UI and the including activities decide as to what should be done with the UI elements included via the fragment. This maximizes reusability.. DRY... :-D