I am using websocket for the first time, It's a Uber kind of application. I am receiving data from the socket , the socket connection and receiver is in common class, but i am confused how to pass data for the particular activity or fragment in a optimized way. As per my knowledge i thought of using Broadcast receiver in required class, but its not a good way ...So any help would be appreciated.
found a good solution i don't think it's the ultimate but, it works faster than Brad cast receiver.
I created a Interface in Main Activity, with a method that send the received data.
public class MainActivity extends AppCompatActivity{
SendData sendData;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public interface SendData {
public void sendData(String data);
}
}
In Fragment Class where i need the response from Main Activity, I implemented the above Interface of Main Activity.
public class Storage extends Fragment implements MainActivity.SendData{
View view;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
view = inflater.inflate(R.layout.driver_info_fragment,container,false);
return view;
}
#Override
public void SendData(String data) {
String dataReceived = data;
}
}
When i receive the data in Main Activity i will get the current fragment, if i want data to be sent to that fragment then i should have implemented the Main Activity Interface in that fragment and Create a casting in Main Class when i have the data and notify the fragment with the value
public class MainActivity extends AppCompatActivity{
#Override
public void notifySocketMessage(final String message) {
if(message != null){
dataPasser = // define the fragment class name where you need to send the data.
dataPasser.onDataPass(message); // add the message to the notifier
}
}
}
Related
On my activity a show a Custom DialogFragement. But when I minimize the app while the dialog is opened i get this error
java.lang.RuntimeException: Parcelable encountered IOException writing serializable object (name = xxx.xxx.MyActivity$24)
at android.os.Parcel.writeSerializable(Parcel.java:1468)
at android.os.Parcel.writeValue(Parcel.java:1416)
at android.os.Parcel.writeArrayMapInternal(Parcel.java:686)
at android.os.BaseBundle.writeToParcelInner(BaseBundle.java:1330)
at android.os.Bundle.writeToParcel(Bundle.java:1079)
at android.os.Parcel.writeBundle(Parcel.java:711)
at android.support.v4.app.FragmentState.writeToParcel(Fragment.java:144)
at android.os.Parcel.writeTypedArray(Parcel.java:1254)
at ....
... 23 more
java.io.NotSerializableException: xxx.xxx.MyActivity
at java.io.ObjectOutputStream.writeNewObject(ObjectOutputStream.java:1344)
xxxxx
For the moment to fix this I have set this in the dialog fragment which seems to works but I don't like these kind of of dirty tricks
#Override
public void onPause() {
dismiss();
super.onPause();
}
Anyone can tell me what causes this exception in the first place ?
The onCreate of the custom DialogFragment:
public static MyCustomDialog newInstance(double lat, double lng, MyListener listener) {
MyCustomDialog dialogFragment = new MyCustomDialog();
Bundle bundle = new Bundle();
bundle.putDouble(ARG_LAT, lat);
bundle.putDouble(ARG_LNG, lng);
bundle.putSerializable(ARG_LISTENER, listener);
dialogFragment.setArguments(bundle);
return dialogFragment;
}
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.dialog_layout, null, false);
final double lat = getArguments().getDouble(ARG_LAT);
final double lng = getArguments().getDouble(ARG_LNG);
listener = (MyListener) getArguments().getSerializable(ARG_LISTENER);
TextView saveBtn = (TextView) view.findViewById(R.id.save_btn);
saveBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
/* some processing */
listener.onSave();
}
});
return view;
}
MyListener is an interface. I thought at first that this could have been the problem but even if I dont put in the bundle I get the same error, so it must be from something else.
Activity side inside a button on click:
MyCustomDialog myCustomDialog = MmyCustomDialog.newInstance(lat, lon, listener);
myCustomDialog.show(getSupportFragmentManager(), "tag");
I see this line in your code:
listener = (MyListener) getArguments().getSerializable(ARG_LISTENER);
If I guess correctly, MyListener is implemented either by an inner class of your Activity or by the Activity itself. Either way, MyListener holds a reference to the Activity. Please note that if your are creating an anonymous inner class, that is:
MyListener listener = new MyListener() { ... }
it still holds a reference to your Activity.
When the Fragment needs to be destroyed, the arguments Bundle is stored in the fragment state Parcel. Android tries to serialize MyListener, however Activity is not Serializable and it fails.
The usual pattern is to declare your listener interface in your Fragment:
public class MyFragment extends Fragment {
...
public interface Callbacks {
void doSomething();
}
...
Then an Activity that hosts the Fragment implements this interface:
public class MyActivity extends AppCompatActivity implements MyFragment.Callbacks {
...
#Override
public void doSomething() {
// do your stuff
}
...
In onAttach of your Fragment you cast the Fragment's host to your Callbacks and set the field.
#Override
public void onAttach(Context context) {
super.onAttach(context);
if (getHost() instanceof Callbacks) {
mCallbacks = (Callbacks) getHost();
} else {
throw new AssertionError("Host does not implement Callbacks!");
}
}
PS In the documentation you may see a version of onAttach method taking an Activity. The version above is deprecated from API 23. Until then, Fragments could be hosted only by Activities. Now, Fragments can be hosted by arbitrary objects and operate in any Context. That being said, you probably will host your Fragments inside Activities anyway, and your context and host will be the same.
try using this method
dismissAllowingStateLoss();
instead of
dismiss();
I have an activity with 3 fragments, currently I use ViewPager. I want to implement MVP and communicate between activity presenter and fragment presenters i.e:
Passing data from activity presenter to fragment presenters
Sending event from fragment presenters to activity presenter
...
But I don't know how to do it in official way. I can use BusEvent but I don't think it's a good practice.
Communication between fragments and activity or vice-versa can be done by using
nnn's answer or you could use ViewModel and LiveData witch provides a cleaner way and respect the lifecycle from fragments and activities which can save from writing a few lines of code in attempt to prevent a a non-visible fragment from receiving data on the background.
First you extend the ViewModel class, initialize the Livedata and some helper methods.
public class MyViewModel extends ViewModel {
private MutableLiveData<String> toFragmentA, toFragmentB;
private MutableLiveData<List<String>> toAllFragments;
public MyViewModel() {
toFragmentA = new MutableLiveData<>();
toFragmentB = new MutableLiveData<>();
toAllFragments = new MutableLiveData<>();
}
public void changeFragmentAData(String value){
toFragmentA.postValue(value);
}
public void changeFragmentBData(String value){
toFragmentB.postValue(value);
}
public void changeFragmentAllData(List<String> value){
toAllFragments.postValue(value);
}
public LiveData<String> getToFragmentA() {
return toFragmentA;
}
public LiveData<List<String>> getToAllFragments() {
return toAllFragments;
}
public LiveData<String> getToFragmentB() {
return toFragmentB;
}
}
Then you initialize the ViewModel on your activity.
public class MainActivity extends AppCompatActivity {
private ViewPager viewPager;
private TabLayout tabLayout;
MyViewModel mViewModel;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mViewModel = ViewModelProviders.of(this)
.get(MyViewModel.class);
viewPager.setAdapter(new Adapter(getSupportFragmentManager()));
}
}
reading the data in the fragments:
#Override
public void onActivityCreated(#Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
mViewModel = ViewModelProviders.of(getActivity()).get(MyViewModel.class);
mViewModel.getToAllFragments().observe(this, new Observer<List<String>>() {
#Override
public void onChanged(List<String> s) {
myList.addAll(s);
//do something like update a RecyclerView
}
});
mViewModel.getToFragmentA().observe(this, new Observer<String>() {
#Override
public void onChanged(String s) {
mytext = s;
//do something like update a TextView
}
});
}
to change the values of any of the live datas you can use one of the methods in any of the fragments or in the activity:
changeFragmentAData();
changeFragmentBData();
changeFragmentAllData();
Whats happing behind the scenes:
when you use mViewModel = ViewModelProviders.of(this).get(MyViewModel.class) you are creating a n instance of ViewModel and binding it to the lifecycle of the given activity of fragment so the view model is destroid only the the activity or fragement is stopped. if you use mViewModel = ViewModelProviders.of(getActivity()).get(MyViewModel.class)you are bindig it to the lifecycle if the parentactivity`
when you use mViewModel.getToFragmentA().observe() or mViewModel.getToFragmentB().observe() or mViewModel.getToAllFragments().observe() you are connecting the LiveData in MyViewModel class to the given fragment or activity an the value of the onChange() method is updated in all the classes that are observing the method.
I recomend for personal expirience a bit of research about Livedata end ViewModel which ou can on youtube or this link
As per my understanding, for your UseCase, suppose ActivityA have a viewPager having 3 Fragments(FragmentA, FragmentB, FragmentC).
ActivityA have ActivityPresenterA
FragmentA have FragmentPresenterA
As per MVP, FragmentPresenterA should be responsible for all the logical and business flows of FragmentA only and should communicate with FragmentA only. Therefore, FragmentPresenterA can not directly communicate with ActivityPresenterA.
For communication from Fragment to Activity, presenter should not be involved and this should be done as we would communicate in non-MVP architecture, i.e. with the help of interface.
Same applies for Activity to Fragment communication.
For communication between Activity and Fragment read here
You can use one presenter for that case.
Used your Activity Presenter to get all the data that your fragments need.
then create an interface class and implement it to your fragments.
For example:
Create a public interface for your PageAFragment (this interface will the bridge of your data from activity to fragment). and use the method of your interface to handle the result from your presenter to view.
This is the example of interface class that I created for received data. for the parameter you can choose what you want it depends on your need, but for me I choose model.
public interface CallbackReceivedData {
void onDataReceived(YourModel model);
}
In MainActivity Class check the instance of fragment that attached into your activity. put your checking instance after you commit the fragment.
public class MainActivity extends AppCompatActivity{
private CallbackReceivedData callbackReceivedData;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//after commit the fragment
if (fragment instanceof PageAFragment){
callbackReceivedData = (CallbackReceivedData)fragment;
}
}
//this is the example method of MainActivity Presenter,
//Imagine it, as your view method.
public void receivedDataFromPresenter(YourModel model){
callbackReceivedData.onDataReceived(model);
}
}
I assumed that the receivedDataFromPresenter is the received method of our view and get data to presenter.
And now we will pass the data from presenter to callbackReceivedData
In PageAFragment implement the CallbackReceivedData and Override the onDataReceived method. Now you can passed the data from activity to your fragment.
public class PageAFragment extends Fragment implements CallbackReceivedData{
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public void onDataReceived(YourModel model) {
}
}
Note: Alternative way, you can use Bundle and pass the data with the use of setArguments.
If you want to send Event from Fragment to Activity you can follow this Idea.
Create an Interface class and implement it to your MainActivity and Override the method from interface to your activity, for My case I do it something like this.
Here's my CallbackSendData Class.
public interface CallbackSendData {
void sendDataEvent(String event);
}
Implement CallbackSendData interface to your MainActivity and Override the sendDataEvent method.
public class MainActivity extends AppCompatActivity implements CallbackSendData{
private CallbackReceivedData callbackReceivedData;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//after commit the fragment
if (fragment instanceof PageAFragment){
callbackReceivedData = (CallbackReceivedData)fragment;
}
}
//this is the example method of MainActivity Presenter,
//Imagine it, as your view method.
public void receivedDataFromPresenter(YourModel model){
callbackReceivedData.onDataReceived(model);
}
#Override
public void sendDataEvent(String event){
//You can now send the data to your presenter here.
}
}
And to your PageAFragment you need to use attach method to cast your interface. The attach method called once the fragment is associated with its activity. If you want to understand the lifecycle of fragment just click this link: https://developer.android.com/reference/android/app/Fragment.html.
public class PageAFragment extends Fragment implements CallbackReceivedData{
private CallbackSendData callbackSendData;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public void onDataReceived(YourModel model) {
//Received the data from Activity to Fragment here.
}
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup
container, #Nullable Bundle savedInstanceState) {
return inflater.inflate(R.layout.PagerAFragment, container,
false);
}
#Override
public void onViewCreated(View view, #Nullable Bundle
savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
Button Eventbutton;
Eventbutton = view.findViewById(R.id.event_button);
Eventbutton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
callbackSendData.sendDataEvent("send Data sample");
}
});
}
#Override
public void onAttach(Context context) {
super.onAttach(context);
try{
callbackSendData = (CallbackSendData) context;
}catch (ClassCastException e){
e.printStackTrace();
}
}
}
And now you can use the CallbackSendData to send the data from activity to fragment.
Note: It's much easier if you are using Dependency Injection to your project, you can use Dagger2 library.
Goodluck.
To communicate between a Fragment and an Activity (whether between their presenters or their classes), you need an interface that your activity implements (like ShoppingInteractor).
This way you can call ((ShoppingInteractor)getActivity()).doSomething() in the fragments. If you want your activity's presenter to handle the task, you need to call the presenter in the doSomething inside the activity.
You can do the same with the fragments with another interface and call the fragment's interactor inside the activity.
You can even have a Presenter getPresenter() inside these interfaces to have access to the actual presenter. (((ShoppingInteractor)getActivity()).getPresenter().sendData(data)). Same goes for the fragments.
If you want to use MVP, the first step is to create one presenter for each View, I mean, If you have 3 fragments, then would have 3 presenters. I think that is a bad idea to create one presenter for 4 views (activity and 3 fragments).
Dynamic data:
Here is an example using rxjava2, dagger2 and moxy.
Conditionalities:
Presenters do not depend on the life cycle of the view
One presenter - one view. The views do not share the presenters among themselves and one view has only one presenter.
The solution is similar to the EventBus, but instead uses Subject with a limited lifetime. It is in the component that is created when the activity starts and is destroyed when it exits. Both activity and fragments have an implicit access to it, they can change the value and respond to it in their own way.
Example project: https://github.com/Anrimian/ViewPagerMvpExample
Static data:
Just use arguments in the fragment and that's it.
So i have a FragmentPagerAdapater called SectionsPagerAdapter and a fragment called TeamFragment where I display data from a specific team. So basically I don't want to create different fragments for each team. That is an overkill. I just want 1 fragment which basically connects to the backend then collects the data based on the team then displays that data. But I dont know how to pass the Team name(a string type) from SectionsPagerAdapter to the TeamFragment so that in TeamFragment, I can easily know what to retrieve from the backend. My backend in parse.com. Please help me figure this out and learn. Thanks
So this is was solved my problem. In my sectionsPagerAdapter class i had the below code
Bundle args = new Bundle();
args.putString("TeamName", team);
TeamFragment teamFragment = new TeamFragment();
teamFragment.setArguments(args);
In onCreateView of my TeamFragment, i had the following
Bundle bundle = this.getArguments();
mTeam = bundle.getString("TeamName");
hope this can help someone else. Thanks
Communicating data into fragments is typically done through a simple setter function that is called by the activity that instantiates or contains the fragment:
public class MyActivity extends FragmentActivity {
#Override
protected void onCreate(Bundled savedInstanceState) {
// ...
TeamFragment fragment =
(TeamFragment) (getSupportFragmentManager().findFragmentById(fragmentId));
fragment.setTeamName(teamName);
// ...
}
For communicating data back to the activity, is typically done using a fragment-specific "Listener" interface. This listener can be attached using the same method (by calling a method on the fragment in the parent activity to register the listener) or it can be done by requiring that the parent Activity implement the listener interface, and casting the parent activity to this listener interface in onAttach() (though the latter approach is not as clean of an approach). Example:
public class MyActivity extends FragmentActivity {
#Override
protected void onCreate(Bundled savedInstanceState) {
// ...
TeamFragment fragment =
(TeamFragment) (getSupportFragmentManager().findFragmentById(fragmentId));
fragment.setTeamName(teamName);
fragment.setTeamSelectedListener(new TeamSelectedListenerImpl());
// ...
}
Or:
public class TeamFragment extends Fragment {
public interface TeamSelectedListener {
// ...
}
// ...
#Override
protected void onAttach(Activity activity) {
teamSelectedListener = (TeamSelectedListener) activity;
}
// ...
}
public class MyActivity
extends FragmentActivity
implements TeamFragment.TeamSelectedListener {
// ...
}
Please please don't minus my question i confused when googling.
I used Android Tab Layout with Swipeable Views in my code for when user pressed setting button on an activity.
now I need send message from TopRatedFragment.java that extends from fragment to the activity that call the mainActivity of "Android Tab Layout with Swipeable Views".
You can do this by implementing a call back
create an interface first
public interface CommunicationInterface {
public void onSuccess();
public void onFailed();
}
then in your activity implement the interface
public class YourActivity extends ActionBarActivity implements CommunicationInterface {
//default functions
#Override
public void onSuccess() {
//stuff you want to do in the acivity
}
#Override
public void onFailed() {
//stuff you want to do in the acivity
}
}
Now in the fragment
public class yourfragment extends Fragment {
CommunicationInterface callback;
//stuffs that usually come in yor fragment and like OncreateView etc
#Override
public void onActivityCreated(#Nullable Bundle outState) {
super.onActivityCreated(outState);
//after all the stuff you want to do in your fragment then implement //call back function to communicate with the activity
callback= (CommunicationInterface) getActivity();
callback.onSuccess();//according to your purpose use where ever you like
callback.onFailed();//according to your purpose use where ever you like
}
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
callback= (CommunicationInterface) activity;
}
}
Take a close look on this reference:
Creating event callbacks to the activity
The android docs recommend using this pattern of having the parent activity implement an interface of the fragment (Basically calling methods on it)
class MyFragment extends Fragment {
interface Listener {
public void onSomeEvent();
}
private void somethingHappeninInTheFragment() {
// let the activity know
((Listener) getActivity()).onSomeEVent();
}
}
class MyActivity extends Activity implements MyFragment.Listener {
// etc
#Override
public void onSomeEvent() {
// handle the message from the fragment
}
}
Explained with a more concrete example here: http://developer.android.com/guide/components/fragments.html#EventCallbacks
Here's the solution:
Step 1 : From your fragment.
Intent i = new Intent(getActivity(), YourActivity.class);
i.putExtra("key", "Your value1");
i.putExtra("key2", "Your value2");
i.putExtra("key3", "Your value3");
getActivity().startActivity(i);
Step 2 : In your Activity where you want the result
Intent getResults = getIntent();
String firstValue = getResults.getStringExtra("key1");
String secondValue = getResults.getStringExtra("key2");
String thirdValue = getResults.getStringExtra("key3");
Use those values your needs are.
Hope this helps.. :)
Hy,
My activity must receive an object using sockets ..
This activity has within fragment A and fragment B.
I wish that every time the activity receiving the object, send it to fragment A.
how can I do?
I think this is a perfect example of where an event bus would be very handy. Check out Square's Otto. If you create an event bus and make it available to your activity and to your fragments (either via a static class or using dependency injection) you can send myObject via the bus without the need to serialize it.
Here's some example code. First I create a statically accessible global event bus in OttoBus.java. This is the bus on which we'll pass messages back and forth between the activity and the fragments. In the Activity I assume you'll have some kind of method that receives the data from the socket. The received data will be put in a SocketDataReceivedEvent object and sent on the bus. In your Fragment you register the fragment on the bus when the Fragment is started and unregister it when it's stopped (to avoid leaking). The Fragment must also have a method to handle the SocketDataReceivedEvent. This method can be named whatever you like as long as it's annotated with #Subscribe and takes a SocketDataReceivedEvent as it's only parameter.
---- OttoBus.java
import com.squareup.otto.Bus;
public class OttoBus {
private static Bus bus = new Bus();
public static void register(Object o) {
bus.register(o);
}
public static void post(Object data) {
bus.post(data);
}
public static void unregister(Object o) {
bus.unregister(o);
}
}
---- SocketDataReceivedEvent.java
public class SocketDataReceivedEvent {
public Object data;
public SocketDataReceivedEvent(Object data) {
this.data = data;
}
}
---- YourActivty.java
public class YourActivity extends Activity {
public void receiveSomethingOnSocket(Object theDataYouReceived) {
OttoBus.send(new SocketDataReceivedEvent(theDataYouReceived));
}
}
---- YourFragment.java
public class YourFragment extends Fragment {
#Override
public void onStart() {
super.onStart();
OttoBus.register(this);
}
#Override
public void onStop() {
super.onStop();
OttoBus.unregister(this);
}
#Subscribe
public void onSocketData(final SocketDataReceivedEvent e) {
// do something with e.data
}
}