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Communication Between DialogFragment and Fragment

I am trying to pass information from my alert dialog to my second fragment (I am using tabbed activity layout).
I want to pass information from alert dialog to fragment when I click on my ImageView, but my app keep crashing until I implement my interface inside MainActivity.java. My main mission here is to open alert dialog which contains several buttons. When I click first button I want to print "Test br 3" but it does not work inside my Fragment, it only works inside my MainActivity.java where method prints "Test br 2".
My Main Activity
public class MainActivity extends AppCompatActivity implements ExercisesAlertDialog.DataTransfer {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
SectionsPagerAdapter sectionsPagerAdapter = new SectionsPagerAdapter(this, getSupportFragmentManager());
ViewPager viewPager = findViewById(R.id.view_pager);
viewPager.setAdapter(sectionsPagerAdapter);
TabLayout tabs = findViewById(R.id.tabs);
tabs.setupWithViewPager(viewPager);
}
#Override
public void ApplyData() {
System.out.println("Test br 2");
}
My Fragment
public class Frag2 extends Fragment implements ExercisesAlertDialog.DataTransfer {
ImageView plusbtn;
#Nullable
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.frag2, container, false);
plusbtn = (ImageView) v.findViewById(R.id.plusbtn);
plusbtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
ExercisesDialog();
}
});
return v;
}
public void ExercisesDialog()
{
ExercisesAlertDialog exercisesAlertDialog = new ExercisesAlertDialog();
exercisesAlertDialog.show(getFragmentManager(), "Exercises Dialog");
}
#Override
public void ApplyData() {
System.out.println("Test br 3");
}
My Alert Dialog
public class ExercisesAlertDialog extends AppCompatDialogFragment {
ImageButton one, two;
private DataTransfer listener;
public int first;
#Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
final AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
LayoutInflater inflater = getActivity().getLayoutInflater();
View v = inflater.inflate(R.layout.workout_custom_menu, null);
builder.setView(v);
builder.setTitle("Choose your Workout");
builder.setPositiveButton("Cancel", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
dismiss();
}
});
one = (ImageButton) v.findViewById(R.id.first);
two = (ImageButton) v.findViewById(R.id.second);
one.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
first = 1;
if(first ==1)
{
listener.ApplyData();
}
}
});
return builder.create();
}
public interface DataTransfer
{
void ApplyData();
}
#Override
public void onAttach(Context context) {
super.onAttach(context);
try {
listener = (DataTransfer) context;
}
catch (ClassCastException e)
{
throw new ClassCastException(toString() + "Must implement DataTransfer");
}
}
}

I changed getChildFragmentManager() instead of getFragmentManager() in the show() call. Second thing is onAttach() to listener = (DataTransfer) getParentFragment(); instead of context.

How to Access Activity(except mainactivity) from Fragment?

I created my test project where i code to communicate between two fragments but actully I want to access activity from fragment.
Here is code to connect fragment to fragment, its working absolutely right without any error but now i want to change this code to connect activity from fragment instead of fragment to fragment communication.
So Please change this code to access activities from fragment. I stuck on this issue for than a week.So Guys please resolve this.
here is my mainaactivity:
public class MainActivity extends AppCompatActivity implements FragmentA.FragmentAListener, FragmentB.FragmentBListener {
private FragmentA fragmentA;
private FragmentB fragmentB;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
fragmentA = new FragmentA();
fragmentB = new FragmentB();
getSupportFragmentManager().beginTransaction()
.replace(R.id.container_a, fragmentA)
.replace(R.id.container_b, fragmentB)
.commit();
}
#Override
public void onInputASent(CharSequence input) {
fragmentB.updateEditText(input);
}
#Override
public void onInputBSent(CharSequence input) {
fragmentA.updateEditText(input);
}
Here is my FragmentA.java:
public class FragmentA extends Fragment {
private FragmentAListener listener;
private EditText editText;
private Button buttonOk;
public interface FragmentAListener {
void onInputASent(CharSequence input);
}
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_a, container, false);
editText = v.findViewById(R.id.edit_text);
buttonOk = v.findViewById(R.id.button_ok);
buttonOk.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
CharSequence input = editText.getText();
listener.onInputASent(input);
}
});
return v;
}
public void updateEditText(CharSequence newText) {
editText.setText(newText);
}
#Override
public void onAttach(Context context) {
super.onAttach(context);
if (context instanceof FragmentAListener) {
listener = (FragmentAListener) context;
} else {
throw new RuntimeException(context.toString()
+ " must implement FragmentAListener");
}
}
#Override
public void onDetach() {
super.onDetach();
listener = null;
}
}
Here is my FragmentB.java:
public class FragmentB extends Fragment {
private FragmentBListener listener;
private EditText editText;
private Button buttonOk;
public interface FragmentBListener {
void onInputBSent(CharSequence input);
}
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_b, container, false);
editText = v.findViewById(R.id.edit_text);
buttonOk = v.findViewById(R.id.button_ok);
buttonOk.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
CharSequence input = editText.getText();
listener.onInputBSent(input);
}
});
return v;
}
public void updateEditText(CharSequence newText) {
editText.setText(newText);
}
#Override
public void onAttach(Context context) {
super.onAttach(context);
if (context instanceof FragmentBListener) {
listener = (FragmentBListener) context;
} else {
throw new RuntimeException(context.toString()
+ " must implement FragmentBListener");
}
}
#Override
public void onDetach() {
super.onDetach();
listener = null;
}
}
Here is my Fertilizers.java file which i want to access from FragmentA.:
public class Fertilizers extends AppCompatActivity {
RecyclerView mRecyclerView;
List<FertilizerData> myFertilizersList;
FertilizerData mFertilizersData;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_fertilizers);
mRecyclerView = (RecyclerView)findViewById(R.id.recyclerView);
GridLayoutManager gridLayoutManager;
gridLayoutManager = new GridLayoutManager(Fertilizers.this, 1);
mRecyclerView.setLayoutManager(gridLayoutManager);
myFertilizersList = new ArrayList<>();
mFertilizersData = new FertilizerData("Urea Fertilizer","Urea is a concent","Rs.1900",R.drawable.urea);
myFertilizersList.add(mFertilizersData);
myFertilizersList.add(mFertilizersData); }
}
please write here a block of code to call Fertilzers Activity from FragmentA, I,ll be very thankful to you.

Calling getActivity() in your fragment gives you the calling activity so if MainActivity started your fragment then you would do
(MainActivity(getActivity())).something_from_your_main_activity

Solution found by itself regarding this issue.
FragmentHome.java class should look like this:
public class FragmentHome extends Fragment {
private Button button;
public FragmentHome(){
}
public interface OnMessageReadListener
{
public void onMessageRead(String message);
}
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_home, container, false);
button = (Button)v.findViewById(R.id.bn);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent intent = new Intent(getActivity(), Fertilizers.class);
intent.putExtra("some"," some data");
startActivity(intent);
}
});
return v;
}
}
FertilizersActivity.java should look like this:
public class Fertilizers extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_fertilizers);
Bundle bundle = getIntent().getExtras();
if (bundle != null){
if(bundle.getStringArrayList("some") !=null){
Toast.makeText(getApplicationContext(),"data:" + bundle.getStringArrayList("some"),Toast.LENGTH_LONG).show();
}
}
}
}

Android ListView with detail page null object

I am creating a listview from the contents of my api, if I click on a listview item I want to show a new view with more details for that clicked item, currently the listview gets shown properly but if I click on an item the app crashed and I get this error message:
> java.lang.RuntimeException: Unable to start activity
> ComponentInfo{de.dev.app/de.dev.app.ui.quote.ArticleDetailActivity}:
> java.lang.NullPointerException: Attempt to invoke virtual method
> 'java.lang.String de.dev.app.jokeapp.entities.Joke.getTitle()' on a null
> object reference ... Caused by: java.lang.NullPointerException:
> Attempt to invoke virtual method 'java.lang.String
> de.dev.app.entities.Joke.getTitle()' on a null object reference
> at
> de.dev.app.ui.quote.ArticleDetailFragment.onCreateView(ArticleDetailFragment.java:100)
The error points to this lines in my ArticleDetailFragment.java:
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflateAndBind(inflater, container, R.layout.fragment_article_detail);
if (!((BaseActivity) getActivity()).providesActivityToolbar()) {
((BaseActivity) getActivity()).setToolbar((Toolbar) rootView.findViewById(R.id.toolbar));
}
collapsingToolbar.setTitle(jokeItem.getTitle()); // points here
author.setText(jokeItem.getTitle());
quote.setText(jokeItem.getTitle());
jokeHeader.setText(jokeItem.getTitle());
jokeContent.setText(jokeItem.getContent());
return rootView;
}
This is my onAttach method:
#Override
public void onAttach(Context context) {
super.onAttach(context);
Bundle bundle = getArguments();
if(bundle == null) {
getActivity().finish();
return;
}
jokeItem = (Joke)bundle.getSerializable("joke");
}
This is my ArticleDetailFragment looks like:
public class ArticleDetailFragment extends BaseFragment {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments().containsKey(ARG_ITEM_ID)) {
// load dummy item by using the passed item ID.
dummyItem = DummyContent.ITEM_MAP.get(getArguments().getString(ARG_ITEM_ID));
}
SharedPreferences preferences = this.getActivity().getSharedPreferences("pref", Context.MODE_PRIVATE);
tokenManager = TokenManager.getInstance(preferences);
service = RetrofitBuilder.createServiceWithAuth(ApiService.class, tokenManager);
setHasOptionsMenu(true);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflateAndBind(inflater, container, R.layout.fragment_article_detail);
if (!((BaseActivity) getActivity()).providesActivityToolbar()) {
// No Toolbar present. Set include_toolbar:
((BaseActivity) getActivity()).setToolbar((Toolbar) rootView.findViewById(R.id.toolbar));
}
collapsingToolbar.setTitle(jokeItem.getTitle());
author.setText(jokeItem.getTitle());
return rootView;
}
#Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
inflater.inflate(R.menu.sample_actions, menu);
super.onCreateOptionsMenu(menu, inflater);
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.action_settings:
// your logic
return true;
}
return super.onOptionsItemSelected(item);
}
#Override
public void onAttach(Context context) {
super.onAttach(context);
Bundle bundle = getArguments();
if(bundle == null) {
getActivity().finish();
return;
}
jokeItem = (Joke)bundle.getSerializable("joke");
}
}
My ArticleDetailActivity
public class ArticleDetailActivity extends BaseActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_detail);
if (getSupportActionBar() != null) {
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
}
ArticleDetailFragment fragment = ArticleDetailFragment.newInstance(getIntent().getStringExtra(ArticleDetailFragment.ARG_ITEM_ID));
getFragmentManager().beginTransaction().replace(R.id.article_detail_container, fragment).commit();
}
#Override
public boolean providesActivityToolbar() {
return false;
}
}
Calling the ArticleDetailActivity in my ListActivit like this:
public class ListActivity extends BaseActivity implements ArticleListFragment.Callback {
...
#Override
public void onItemSelected(Joke joke) {
Intent detailIntent = new Intent(this, ArticleDetailActivity.class);
// detailIntent.putExtra(ArticleDetailFragment.ARG_ITEM_ID, id);
startActivity(detailIntent);
}
...

Call DetailActivity like this from your ListActvity,
Intent detailIntent = new Intent(this, ArticleDetailActivity.class);
// detailIntent.putExtra(ArticleDetailFragment.ARG_ITEM_ID, id);
Bundle bundle = new Bundle();
bundle.putSerializable("joke", joke);
detailIntent.putExtras(bundle);
startActivity(detailIntent);
and change your ArticleDetailActivity change like this, we need to send data to fragment
public class ArticleDetailActivity extends BaseActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_detail);
// Show the Up button in the action bar.
if (getSupportActionBar() != null) {
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
}
ArticleDetailFragment fragment = new ArticleDetailFragment();
fragment.setArguments(getIntent().getExtras());
getFragmentManager().beginTransaction().replace(R.id.article_detail_container, fragment).commit();
}
#Override
public boolean providesActivityToolbar() {
return false;
}
}

Add this line of code to your ArticleDetailFragment class
#BindView(R.id.title)
TextView title;

Handling Multiple Fragments when orientation changes

I have a MainActivity, and I want to attach a fragment with 3 buttons in it to that activity. On clicking button 1 it should replace this fragment with another fragment. But when I change orientation the current fragment and the old fragment are both getting attached. Can someone help me solve this ?
Following is my MainActivity.java:
public class MainActivity extends AppCompatActivity implements OnButtonsClickListener {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
getSupportFragmentManager().beginTransaction()
.add(R.id.mainactivity, new FragmentHomepage(), "aboutMe")
.commit();
}
#Override
public void button1Action() {
FragmentAboutMe fragmentAboutMe=new FragmentAboutMe();
getSupportFragmentManager().beginTransaction()
.add(R.id.mainactivity,fragmentAboutMe)
.commit();
}
#Override
public void button2Action() {
Intent intent =new Intent(this,ActivityMasterDetail.class);
startActivity(intent);
}
#Override
public void button3Action() {
Intent intent =new Intent(this,ActivityViewPager.class);
startActivity(intent);
}
}
This is my FragmentHomepage.java:
public class FragmentHomepage extends Fragment {
private static final String ARG_SECTION_NUMBER ="section number";
OnButtonsClickListener onButtonsClickListener;
public static FragmentHomepage newInstance(int sectionNumber){
FragmentHomepage fragmentHomepage=new FragmentHomepage();
Bundle args=new Bundle();
args.putInt(ARG_SECTION_NUMBER,sectionNumber);
fragmentHomepage.setArguments(args);
return fragmentHomepage;
}
public FragmentHomepage(){}
#Override
public void onAttach(Context context) {
super.onAttach(context);
try {
onButtonsClickListener= (OnButtonsClickListener) context;
} catch (Exception e) {
e.printStackTrace();
}
}
#Override
public void onActivityCreated(#Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
final Button button1= (Button) getActivity().findViewById(R.id.aboutMe);
final Button button2= (Button) getActivity().findViewById(R.id.task2);
final Button button3= (Button) getActivity().findViewById(R.id.task3);
button1.setOnClickListener(new Button.OnClickListener() {
#Override
public void onClick(View v) {
onButtonsClickListener.button1Action();
}
});
button2.setOnClickListener(new Button.OnClickListener() {
#Override
public void onClick(View v) {
onButtonsClickListener.button2Action();
}
});
button3.setOnClickListener(new Button.OnClickListener() {
#Override
public void onClick(View v) {
onButtonsClickListener.button3Action();
}
});
}
#Nullable
#Override
public View onCreateView(final LayoutInflater inflater,
ViewGroup container,
Bundle savedInstanceState) {
View rootView=null;
rootView =inflater.inflate(R.layout.fragment_homepage,container,false);
return rootView;
}
}
and my second activity is as follows
(in FragmentAboutMe.java):
public class FragmentAboutMe extends Fragment {
int counters=0;
#Override
public void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if(savedInstanceState==null)counters=0;
else counters=savedInstanceState.getInt("count");
}
#Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putInt("count",13);
}
#Nullable
#Override
public View onCreateView(LayoutInflater inflater,
ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_aboutme,container,false);
}
}

In your onCreate() method put a check whether the fragment is already present. Android automatically restores the fragment manager state upon orientation change and hence upon orientation change, the fragment which you added on button click would automatically be added. Thus if you will add new fragment in onCreate() without check, this would result in adding the 2 fragments. This is causing the issue.
FragmentManager fm = getSupportFragmentManager();
if (fm.findfragmentById(R.id.mainactivity) == null) {
FragmentHomepage fragment = new FragmentHomepage ();
fm.beginTransaction().add (R.id.mainactivity, fragment).commit();
}

You would want to save the state. You would need to extend Fragment to store the objects that need saving.
Override the onConfigurationChanged(..) and it should work out.
When I had to handle screen orientation changes, I recall having used this reference [link].

There are two ways.
Either you need to save the state in the bundle in onSaveInstanceState() method. Also save the states of fragment.
When activity recreate itself then check the value of bundle inside onCreate() or onRestoreInstanceState() method. Now initialize all the objects as before.
Else
set the value of activity inside manifest file as
android:configChanges="layoutDirection|orientation|screenLayout|screenSize"
and override the method.
#Override
public void onConfigurationChanged(Configuration newConfig) {
}
Second technique will not allow the activity to restart on orientation change.

Android - How to send data from main activity to loaded fragment

I want to have a function that is constant between all my Fragments placed in MainActivity. I am not sure how to pass the data to the active Fragment since the Fragment will be unaware of the function being run.
I have tried creating an interface in the MainActivity and have the Fragment implement the MainActivity.OnDataPass. but not sure how to initiate the interface in the MainActivity I keep getting a NullPointerException.
In my main activity:
public class Mainactivity extends FragmentActivity{
OnDataPass dataPasser;
BroadcastReceiver receiver;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
receiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
String str = intent.getStringExtra("data");
dataPasser.onDataPass(str);
}
};
}
public interface OnDataPass {
public void onDataPass(String data);
}
}
In my Fragment
public class Storage extends Fragment implements Mainactivity.OnDataPass{
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
mrootview = (ViewGroup) inflater.inflate(R.layout.storage, container, false);
return mrootview;
}
#Override
public void onDataPass(String data) {
Log.v(TAG, data);
}
}
am I even on the right track or is there a better way to send data to the fragment?

You are pretty far already:
public class Mainactivity extends FragmentActivity{
OnDataPass dataPasser;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//When you create your fragment, keep a reference of it in the dataPasser variable
dataPasser = /* your storage fragment class or any other fragment that implements onDataPass*/
......
receiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
String str = intent.getStringExtra("data");
dataPasser.onDataPass(str);
}
};
}
public interface OnDataPass {
public void onDataPass(String data);
}
}