I've been using for a while the best practice recommended by Google of having a MyFragment.newInstance() static function. Though thinking about it, why can't we simplify it removing this static function, the call to onCreate to access the arguments, and only using one bundle to always save and retrieve the latest data when recreating the fragment ?
I made a simple test that seems to work just as fine as the slightly heavier current practice.
The state persisted after activity recreation, orientation change, and fragment re-creation in a FragmentStatePagerAdapter.
Am I missing anything?
public class TestFragment extends Fragment {
private String fragmentText;
public TestFragment() { } // Required empty public constructor
#SuppressLint("ValidFragment")
public TestFragment(String fragmentText) {
// add here other init arguments
// don't save them in any bundle yet
this.fragmentText = fragmentText;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
if (savedInstanceState != null) {
// retrieve all arguments here
fragmentText = savedInstanceState.getString("fragmentText", fragmentText);
}
TextView textView = new TextView(getActivity());
textView.setText(fragmentText);
return textView;
}
#Override
public void onSaveInstanceState(#NonNull Bundle outState) {
super.onSaveInstanceState(outState);
// save everything here once, only when needed
outState.putString("fragmentText", fragmentText);
}
// Add your setters to interact with the fragment
// those changes will persists after fragment re-creation
public void setFragmentText(String fragmentText) {
this.fragmentText = fragmentText;
}
}
Why isn't savedInstanceState bundle enough?
It is enough. The arguments Bundle is added to the saved instance state Bundle automatically.
I made a simple test that seems to work just as fine as the slightly heavier current practice.
Your approach is roughly the same, in terms of lines of code, as is the factory-method approach.
Why do we need to add an additional bundle with setArguments?
You do not "need" it. It is merely an available and recommended pattern for providing input to the fragment. You are welcome to do something else if you wish. Just remember to have the public zero-argument constructor as well as your custom constructor, since the framework will use the public zero-argument constructor when recreating your fragments.
Because savedInstance doesn't call every time. It will be triggered when device screen will be rotated or when inner system kill application due to low memory and some more scenarios. So if you want to pass some values from activities to fragment or fragment to fragment you must have to pass it through Argument. There are plenty of others ways -> you can make static variable and store the value in it but thats not a perfect value to pass value -> it will consume lot of memory. So passing through argument is standard way
I have a main fragment with a viewpager inside it. This viewpager has 2 pages (list fragments). When I start the activty, the main fragment is shown and I also show the first paged fragment. This paged fragment displays data from a db using AsyncTask.
In the main fragment I have:
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
onPageSelected(0);
}
#Override
public void onPageSelected(int position) {
Fragment fragment = (Fragment) pagerAdapter.instantiateItem(viewPager, position);
if (fragment instanceof IPagedFragment) {
((IPagedFragment) fragment).onShown(getActivity());
}
}
And the interface is:
public interface IPagedFragment {
void onShown(FragmentActivity activity);
}
The first issue I have is that I have to pass the activity as a parameter because when onShown gets called, the activity is still null.
Furthermore, the paged fragments use progressbar logic similar to the LoginActivity sample. I also get the following exception:
IllegalStateException: Fragment PagedFragment1{4201f758} not attached to Activity
at android.support.v4.app.Fragment.getResources(Fragment.java:620)
So what is the correct stage to start retrieving data from db once the paged fragment is fully available to the UI?
Issues like yours is the reason some developers are starting to question if fragments are really that good or useful.
Also "the correct" is debatable as you can do it in a variety of places and different developers will give you different answers, But let me try to supply you some useful info.
The attach/detach callbacks:
public void onAttach(Activity activity);
public void onDetach();
between those two methods any call to getActivity() will return the non-null activity the fragments is connected to. You can override them and use a private boolean isAttached to keep track of that call.
Also useful is the:
public void onActivityCreated (Bundle savedInstanceState)
this method is called AFTER the Activity.onCreate method. That is very important if you rely on some initialisation that happened there.
Also it's important to remember that on the moment the fragment transaction happens, the Fragment.onCreate happens after the Activity.onCreate and during rotation it happens before it.
As a general rule of thumb I use the Fragment.onStart() / Fragment.onStop() for getting/listening to data. On those calls, all the UI have been created, the fragment is attached to the activity and those callbacks don't get called if there's a dialog/popup (pause/resume does)
From the documentation:
public void onActivityCreated (Bundle savedInstanceState)
[...] tells the fragment when it is fully associated with the new activity instance.
source: http://developer.android.com/reference/android/app/Fragment.html#onActivityCreated(android.os.Bundle)
To get the reference of your activity, create a local object of fragmentActivity and get your activity reference as shown below.
private FragmentActivity fragmentActivity;
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
fragmentActivity=activity;
}
I have a fragment class that looks like this:
public class MessageFragment extends Fragment {
Context ctx;
Button compose;
public MessageFragment(Context ctx){
this.ctx = ctx;
}
...}
The constructor it gives an error that says
This fragment should provide a default constructor
Meanwhile, I have 4 other fragment classes that are formatted this exact way, but they don't give this error. How can I fix this?
When your Activity is recreated due to a configuration change (such as an orientation change), the system will manage recreating the state of your fragments by creating a new instance of your Fragment, and then passing the arguments in using setArguments(Bundle args). It uses the default constructor to recreate your fragment, which is why it is required. You should never rely on logic that happens in a non-default constructor for your fragment, as you'll immediately break on a configuration change.
Also, passing in a Context to your Fragment seems like a memory leak waiting to happen. It might not, but it's not good practice. Wait until one of the Fragment lifecycle events such as onCreate() or onAttach(), and store a reference to getActivity() as your Context. You can then release the reference in onDetach().
EDIT: Basically, anything you need to pass in for your Fragment to function properly should either be stored in its arguments Bundle, or saved in the onSaveInstanceState(Bundle outState) event and restored in onCreate(Bundle state), otherwise you'll lose it on a config change.
This is why there's a common pattern of a static factory method for creating fragments. For example:
public static Fragment newInstance(String arg1, int arg2) {
Fragment result = new MyFragment();
Bundle args = new Bundle();
args.putString("arg1_key", arg1);
args.putInt("arg2_key", arg2);
result.setArguments(args);
return result;
}
And then use that instead of a non-default constructor. From within your Fragment you can then retrieve the data with:
Bundle args = getArguments();
String arg1 = args.getString("arg1_key");
int arg2 = args.getInt("arg2_key");
Just add a default constructor like this
public MessageFragment(){}
And you should be good.
I've got an activity, containing fragment 'list', which upon clicking on one of its items will replace itself to a 'content' fragment. When the user uses the back button, he's brought to the 'list' fragment again.
The problem is that the fragment is in its default state, no matter what I try to persist data.
Facts:
both fragments are created through public static TheFragment newInstance(Bundle args), setArguments(args) and Bundle args = getArguments()
both fragments are on the same level, which is directly inside a FrameLayout from the parent activity (that is, not nested fragments)
I do not want to call setRetainInstance, because my activity is a master/detail flow, which has a 2 pane layout on larger screens. 7" tablets have 1 pane in portrait and 2 panes in landscape. If I retain the 'list' fragment instance, it will (I think) fuck things up with screen rotations
when the users clicks an item in the 'list' fragment, the 'content' fragment is displayed through FragmentTransaction#replace(int, Fragment, String), with the same ID but a different tag
I did override onSaveInstanceState(Bundle), but this is not always called by the framework, as per the doc: "There are many situations where a fragment may be mostly torn down (such as when placed on the back stack with no UI showing), but its state will not be saved until its owning activity actually needs to save its state."
I'm using the support library
From the bullet 5 above, I guess that low-end devices that need to recover memory after a fragment transaction may call Fragment#onSaveInstanceState(Bundle). However, on my testing devices (Galaxy Nexus and Nexus 7), the framework doesn't call that method. So that's not a valid option.
So, how can I retain some fragment data? the bundle passed to Fragment#onCreate, Fragment#onActivityCreated, etc. is always null.
Hence, I can't make a difference from a brand new fragment launch to a back stack restore.
Note: possible related/duplicate question
This doesn't seem right, but here's how I ended up doing:
public class MyActivity extends FragmentActivity {
private Bundle mMainFragmentArgs;
public void saveMainFragmentState(Bundle args) {
mMainFragmentArgs = args;
}
public Bundle getSavedMainFragmentState() {
return mMainFragmentArgs;
}
// ...
}
And in the main fragment:
public class MainFragment extends Fragment {
#Override
public void onActivityCreated(final Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Bundle args = ((MyActivity) getActivity()).getSavedMainFragmentState();
if (args != null) {
// Restore from backstack
} else if (savedInstanceState != null) {
// Restore from saved instance state
} else {
// Create from fragment arguments
args = getArguments();
}
// ...
}
// ...
#Override
public void onDestroyView() {
super.onDestroyView();
Bundle args = new Bundle();
saveInstance(args);
((MyActivity) getActivity()).saveMainFragmentState(args);
}
#Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
saveInstance(outState);
}
private void saveInstance(Bundle data) {
// put data into bundle
}
}
It works!
if back from backstack, the fragment uses the parameters saved in onDestroyView
if back from another app/process/out of memory, the fragment is restored from the onSaveInstanceState
if created for the first time, the fragment uses the parameters set in setArguments
All events are covered, and the freshest information is always kept.
It's actually more complicated, it's interface-based, the listener is un/registered from onAttach/onDetach. But the principles are the same.
I have two classes. First is activity, second is a fragment where I have some EditText. In activity I have a subclass with async-task and in method doInBackground I get some result, which I save to variable. How can I send this variable from subclass "my activity" to this fragment?
From Activity you send data with intent as:
Bundle bundle = new Bundle();
bundle.putString("edttext", "From Activity");
// set Fragmentclass Arguments
Fragmentclass fragobj = new Fragmentclass();
fragobj.setArguments(bundle);
and in Fragment onCreateView method:
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
String strtext = getArguments().getString("edttext");
return inflater.inflate(R.layout.fragment, container, false);
}
Also You can access activity data from fragment:
Activity:
public class MyActivity extends Activity {
private String myString = "hello";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_my);
...
}
public String getMyData() {
return myString;
}
}
Fragment:
public class MyFragment extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
MyActivity activity = (MyActivity) getActivity();
String myDataFromActivity = activity.getMyData();
return view;
}
}
I´ve found a lot of answers here # stackoverflow.com but definitely this is the correct answer of:
"Sending data from activity to fragment in android".
Activity:
Bundle bundle = new Bundle();
String myMessage = "Stackoverflow is cool!";
bundle.putString("message", myMessage );
FragmentClass fragInfo = new FragmentClass();
fragInfo.setArguments(bundle);
transaction.replace(R.id.fragment_single, fragInfo);
transaction.commit();
Fragment:
Reading the value in the fragment
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
Bundle bundle = this.getArguments();
String myValue = bundle.getString("message");
...
...
...
}
or just
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
String myValue = this.getArguments().getString("message");
...
...
...
}
This answer may be too late. but it will be useful for future readers.
I have some criteria. I have coded for pick the file from intent. and selected file to be passed to particular fragment for further process. i have many fragments having the functionality of File picking. at the time , every time checking the condition and get the fragment and pass the value is quite disgusting. so , i have decided to pass the value using interface.
Step 1: Create the interface on Main Activity.
public interface SelectedBundle {
void onBundleSelect(Bundle bundle);
}
Step 2: Create the SelectedBundle reference on the Same Activity
SelectedBundle selectedBundle;
Step 3: create the Method in the Same Activity
public void setOnBundleSelected(SelectedBundle selectedBundle) {
this.selectedBundle = selectedBundle;
}
Step 4: Need to initialise the SelectedBundle reference which are all fragment need filepicker functionality.You place this code on your fragment onCreateView(..) method
((MainActivity)getActivity()).setOnBundleSelected(new MainActivity.SelectedBundle() {
#Override
public void onBundleSelect(Bundle bundle) {
updateList(bundle);
}
});
Step 5: My case, i need to pass the image Uri from HomeActivity to fragment. So, i used this functionality on onActivityResult method.
onActivityResult from the MainActivity, pass the values to the fragments using interface.
Note: Your case may be different. you can call it from any where from your HomeActivity.
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
selectedBundle.onBundleSelect(bundle);
}
Thats all. Implement every fragment you needed on the FragmentClass. You are great. you have done. WOW...
The best and convenient approach is calling fragment instance and send data at that time.
every fragment by default have instance method
For example :
if your fragment name is MyFragment
so you will call your fragment from activity like this :
getSupportFragmentManager().beginTransaction().add(R.id.container, MyFragment.newInstance("data1","data2"),"MyFragment").commit();
*R.id.container is a id of my FrameLayout
so in MyFragment.newInstance("data1","data2") you can send data to fragment and in your fragment you get this data in MyFragment newInstance(String param1, String param2)
public static MyFragment newInstance(String param1, String param2) {
MyFragment fragment = new MyFragment();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
and then in onCreate method of fragment you'll get the data:
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
}
so now mParam1 have data1 and mParam2 have data2
now you can use this mParam1 and mParam2 in your fragment.
Basic Idea of using Fragments (F) is to create reusable self sustaining UI components in android applications. These Fragments are contained in activities and there are common(best) way of creating communication path ways from A -> F and F-A, It is a must to Communicate between F-F through a Activity because then only the Fragments become decoupled and self sustaining.
So passing data from A -> F is going to be the same as explained by ρяσѕρєя K. In addition to that answer, After creation of the Fragments inside an Activity, we can also pass data to the fragments calling methods in Fragments.
For example:
ArticleFragment articleFrag = (ArticleFragment)
getSupportFragmentManager().findFragmentById(R.id.article_fragment);
articleFrag.updateArticleView(position);
I would like to add for the beginners that the difference between the 2 most upvoted answers here is given by the different use of a fragment.
If you use the fragment within the java class where you have the data you want to pass, you can apply the first answer to pass data:
Bundle bundle = new Bundle();
bundle.putString("edttext", "From Activity");
Fragmentclass fragobj = new Fragmentclass();
fragobj.setArguments(bundle);
If however you use for example the default code given by Android Studio for tabbed fragments, this code will not work.
It will not work even if you replace the default PlaceholderFragment with your FragmentClasses, and even if you correct the FragmentPagerAdapter to the new situation adding a switch for getItem() and another switch for getPageTitle() (as shown here)
Warning: the clip mentioned above has code errors, which I explain later here, but is useful to see how you go from default code to editable code for tabbed fragments)! The rest of my answer makes much more sense if you consider the java classes and xml files from that clip (representative for a first use of tabbed fragments by a beginner scenario).
The main reason the most upvoted answer from this page will not work is that in that default code for tabbed fragments, the fragments are used in another java class: FragmentPagerAdapter!
So, in order to send the data, you are tempted to create a bundle in the MotherActivity and pass it in the FragmentPagerAdapter, using answer no.2.
Only that is wrong again. (Probably you could do it like that, but it is just a complication which is not really needed).
The correct/easier way to do it, I think, is to pass the data directly to the fragment in question, using answer no.2.
Yes, there will be tight coupling between the Activity and the Fragment, BUT, for tabbed fragments, that is kind of expected. I would even advice you to create the tabbed fragments inside the MotherActivity java class (as subclasses, as they will never be used outside the MotherActivity) - it is easy, just add inside the MotherActivity java class as many Fragments as you need like this:
public static class Tab1 extends Fragment {
public Tab1() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.your_layout_name_for_fragment_1, container, false);
return rootView;
}
}.
So, to pass data from the MotherActivity to such a Fragment you will need to create private Strings/Bundles above the onCreate of your Mother activity - which you can fill with the data you want to pass to the fragments, and pass them on via a method created after the onCreate (here called getMyData()).
public class MotherActivity extends Activity {
private String out;
private Bundle results;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_mother_activity);
// for example get a value from the previous activity
Intent intent = getIntent();
out = intent.getExtras().getString("Key");
}
public Bundle getMyData() {
Bundle hm = new Bundle();
hm.putString("val1",out);
return hm;
}
}
And then in the fragment class, you use getMyData:
public static class Tab1 extends Fragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
public Tab1() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.your_layout_name_for_fragment_1, container, false);
TextView output = (TextView)rootView.findViewById(R.id.your_id_for_a_text_view_within_the_layout);
MotherActivity activity = (MotherActivity)getActivity();
Bundle results = activity.getMyData();
String value1 = results.getString("val1");
output.setText(value1);
return rootView;
}
}
If you have database queries I advice you to do them in the MotherActivity (and pass their results as Strings/Integers attached to keys inside a bundle as shown above), as inside the tabbed fragments, your syntax will become more complex (this becomes getActivity() for example, and getIntent becomes getActivity().getIntent), but you have also the option to do as you wish.
My advice for beginners is to focus on small steps. First, get your intent to open a very simple tabbed activity, without passing ANY data. Does it work? Does it open the tabs you expect? If not, why?
Start from that, and by applying solutions such as those presented in this clip, see what is missing. For that particular clip, the mainactivity.xml is never shown. That will surely confuse you. But if you pay attention, you will see that for example the context (tools:context) is wrong in the xml fragment files. Each fragment XML needs to point to the correct fragment class (or subclass using the separator $).
You will also see that in the main activity java class you need to add tabLayout.setupWithViewPager(mViewPager) - right after the line TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs); without this line, your view is actually not linked to the XML files of the fragments, but it shows ONLY the xml file of the main activity.
In addition to the line in the main activity java class, in the main activity XML file you need to change the tabs to fit your situation (e.g. add or remove TabItems). If you do not have tabs in the main activity XML, then possibly you did not choose the correct activity type when you created it in the first place (new activity - tabbed activity).
Please note that in the last 3 paragraphs I talk about the video! So when I say main activity XML, it is the main activity XML in the video, which in your situation is the MotherActivity XML file.
If you pass a reference to the (concrete subclass of) fragment into the async task, you can then access the fragment directly.
Some ways of passing the fragment reference into the async task:
If your async task is a fully fledged class (class FooTask extends AsyncTask), then pass your fragment into the constructor.
If your async task is an inner class, just declare a final Fragment variable in the scope the async task is defined, or as a field of the outer class. You'll be able to access that from the inner class.
From Activity you send data with Bundle as:
Bundle bundle = new Bundle();
bundle.putString("data", "Data you want to send");
// Your fragment
MyFragment obj = new MyFragment();
obj.setArguments(bundle);
And in Fragment onCreateView method get the data:
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
String data = getArguments().getString("data");// data which sent from activity
return inflater.inflate(R.layout.myfragment, container, false);
}
Sometimes you can receive Intent in your activity and you need to pass the info to your working fragment.
Given answers are OK if you need to start the fragment but if it's still working, setArguments() is not very useful.
Another problem occurs if the passed information will cause to interact with your UI. In that case you cannot call something like myfragment.passData() because android will quickly tells that only the thread which created the view can interact with.
So my proposal is to use a receiver. That way, you can send data from anywhere, including the activity, but the job will be done within the fragment's context.
In you fragment's onCreate():
protected DataReceiver dataReceiver;
public static final String REC_DATA = "REC_DATA";
#Override
public void onCreate(Bundle savedInstanceState) {
data Receiver = new DataReceiver();
intentFilter = new IntentFilter(REC_DATA);
getActivity().registerReceiver(dataReceiver, intentFilter);
}
private class DataReceiver extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
int data= intent.getIntExtra("data", -1);
// Do anything including interact with your UI
}
}
In you activity:
// somewhere
Intent retIntent = new Intent(RE_DATA);
retIntent.putExtra("data", myData);
sendBroadcast(retIntent);
Very old post, still I dare to add a little explanation that would had been helpful for me.
Technically you can directly set members of any type in a fragment from activity.
So why Bundle?
The reason is very simple - Bundle provides uniform way to handle:-- creating/opening fragment
-- reconfiguration (screen rotation) - just add initial/updated bundle to outState in onSaveInstanceState()
-- app restoration after being garbage collected in background (as with reconfiguration).
You can (if you like experiments) create a workaround in simple situations but Bundle-approach just doesn't see difference between one fragment and one thousand on a backstack - it stays simple and straightforward. That's why the answer by #Elenasys is the most elegant and universal solution. And that's why the answer given by #Martin has pitfalls
If an activity needs to make a fragment perform an action after initialization, the easiest way is by having the activity invoke a method on the fragment instance. In the fragment, add a method:
public class DemoFragment extends Fragment {
public void doSomething(String param) {
// do something in fragment
}
}
and then in the activity, get access to the fragment using the fragment manager and call the method:
public class MainActivity extends FragmentActivity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
DemoFragment fragmentDemo = (DemoFragment)
getSupportFragmentManager().findFragmentById(R.id.fragmentDemo);
fragmentDemo.doSomething("some param");
}
}
and then the activity can communicate directly with the fragment by invoking this method.
the better approach for sending data from activity class to fragment is passing via setter methods. Like
FragmentClass fragmentClass = new FragmentClass();
fragmentClass.setMyList(mylist);
fragmentClass.setMyString(myString);
fragmentClass.setMyMap(myMap);
and get these data from the class easily.
Use following interface to communicate between activity and fragment
public interface BundleListener {
void update(Bundle bundle);
Bundle getBundle();
}
Or use following this generic listener for two way communication using interface
/**
* Created by Qamar4P on 10/11/2017.
*/
public interface GenericConnector<T,E> {
T getData();
void updateData(E data);
void connect(GenericConnector<T,E> connector);
}
fragment show method
public static void show(AppCompatActivity activity) {
CustomValueDialogFragment dialog = new CustomValueDialogFragment();
dialog.connector = (GenericConnector) activity;
dialog.show(activity.getSupportFragmentManager(),"CustomValueDialogFragment");
}
you can cast your context to GenericConnector in onAttach(Context) too
in your activity
CustomValueDialogFragment.show(this);
in your fragment
...
#Override
public void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
connector.connect(new GenericConnector() {
#Override
public Object getData() {
return null;
}
#Override
public void updateData(Object data) {
}
#Override
public void connect(GenericConnector connector) {
}
});
}
...
public static void show(AppCompatActivity activity, GenericConnector connector) {
CustomValueDialogFragment dialog = new CustomValueDialogFragment();
dialog.connector = connector;
dialog.show(activity.getSupportFragmentManager(),"CustomValueDialogFragment");
}
Note: Never use it like "".toString().toString().toString(); way.
just stumbled across this question, while most of the methods above will work.
I just want to add that you can use the Event Bus Library, especially in scenarios where the component (Activity or Fragment) has not been created, its good for all sizes of android projects and many use cases. I have personally used it in several projects i have on playstore.
You can create public static method in fragment where you will get static reference of that fragment and then pass data to that function and set that data to argument in same method and get data via getArgument on oncreate method of fragment, and set that data to local variables.
I ran into a similar issue while using the latest Navigation architecture component. Tried out all the above-mentioned code with passing a bundle from my calling activity to Fragment.
The best solution, following the latest development trends in Android, is by using View Model (part of Android Jetpack).
Create and Initialize a ViewModel class in the parent Activity, Please note that this ViewModel has to be shared between the activity and fragment.
Now, Inside the onViewCreated() of the fragment, Initialize the Same ViewModel and setup Observers to listen to the ViewModel fields.
Here is a helpful, in-depth tutorial if you need.
https://medium.com/mindorks/how-to-communicate-between-fragments-and-activity-using-viewmodel-ca733233a51c
Kotlin version:
In Activity:
val bundle = Bundle()
bundle.putBoolean("YourKey1", true)
bundle.putString("YourKey2", "YourString")
val fragment = YourFragment()
fragment.arguments = bundle
val fragmentTransaction = parentFragmentManager.beginTransaction()
fragmentTransaction.replace(R.id.your_container, fragment, fragment.toString())
fragmentTransaction.commit()
In the Fragment onCreate():
var value1 = arguments?.getBoolean("YourKey1", default true/false)
var value2 = arguments?.getString("YourKey2", "Default String")
Smartest tried and tested way of passing data between fragments and activity is to create a variables,example:
class StorageUtil {
public static ArrayList<Employee> employees;
}
Then to pass data from fragment to activity, we do so in the onActivityCreated method:
//a field created in the sending fragment
ArrayList<Employee> employees;
#Override
public void onActivityCreated(#Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
employees=new ArrayList();
//java 7 and above syntax for arraylist else use employees=new ArrayList<Employee>() for java 6 and below
//Adding first employee
Employee employee=new Employee("1","Andrew","Sam","1984-04-10","Male","Ghanaian");
employees.add(employee);
//Adding second employee
Employee employee=new Employee("1","Akuah","Morrison","1984-02-04","Female","Ghanaian");
employees.add(employee);
StorageUtil.employees=employees;
}
Now you can get the value of StorageUtil.employees from everywhere.
Goodluck!
My solution is to write a static method inside the fragment:
public TheFragment setData(TheData data) {
TheFragment tf = new TheFragment();
tf.data = data;
return tf;
}
This way I am sure that all the data I need is inside the Fragment before any other possible operation which could need to work with it.
Also it looks cleaner in my opinion.
You can make a setter method in the fragment. Then in the Activity, when you reference to the fragment, you call the setter method and pass it the data from you Activity
In your activity declare static variable
public static HashMap<String,ContactsModal> contactItems=new HashMap<String, ContactsModal>();
Then in your fragment do like follow
ActivityName.contactItems.put(Number,contactsModal);