Pass Data from Fragment to Fragment Through Button Click

Question

In my Android app, I have two fragments. One fragment has an onClickListener and essentially what I am trying to do is create a counter/log of sorts. Every time a button is clicked, I want to update an integer, and then pass String.valueOf(integer) to a TextView in another fragment.

Here is the first Fragment, with the onClickListener:

 public class StartingFragment extends Fragment implements View.OnClickListener {

        public static final String TEA_TYPE_POS = "tea_navdrawer_position";
        public static int COUNT = 0;
        private TeaCounterFragment mTeaCounterFragment;

        // onCreateView method - Returning the layout file
        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
            // Inflating the layout
            View v = inflater.inflate(R.layout.starting_fragment, container, false);


            /* From this point, you do everything in regards to the "v" object */
            Button tea_type1 = (Button) v.findViewById(R.id.tea_type1);
            Button tea_type2 = (Button) v.findViewById(R.id.tea_type2);
            Button tea_type3 = (Button) v.findViewById(R.id.tea_type3);
            Button tea_type4 = (Button) v.findViewById(R.id.tea_type4);
            Button tea_type5 = (Button) v.findViewById(R.id.tea_type5);
            Button tea_type6 = (Button) v.findViewById(R.id.tea_type6);
            Button tea_type7 = (Button) v.findViewById(R.id.tea_type7);
            Button set_timer = (Button) v.findViewById(R.id.set_your_own_timer);




            tea_type1.setText("Oolong");
            tea_type1.setOnClickListener(this);

            tea_type2.setText("White");
            tea_type2.setOnClickListener(this);

            tea_type3.setText("Blooming");
            tea_type3.setOnClickListener(this);

            tea_type4.setText("Black");
            tea_type4.setOnClickListener(this);

            tea_type5.setText("Herbal");
            tea_type5.setOnClickListener(this);

            tea_type6.setText("Green");
            tea_type6.setOnClickListener(this);

            tea_type7.setText("Mate");
            tea_type7.setOnClickListener(this);

            set_timer.setText("Set Your Own Timer");
            set_timer.setOnClickListener(this);

            /* Do your manipulation to your views here, onClick listeners and such */

            // Return the "v" object
            return v;
        }

        @Override
        public void onClick(View view) {
            switch (view.getId()) {
            /*
             * Use the View interface with OnClickListener to get the Button ID's
             * Then you can run a switch on the Buttons (because normally switches
             * cannot be run on buttons
             */

                case R.id.tea_type1:
                    Builder oolongBuilder = new AlertDialog.Builder(StartingFragment.this.getActivity(),
                            AlertDialog.THEME_HOLO_LIGHT);

                    oolongBuilder.setPositiveButton("Hot",
                            //Starts OolongTeaActivity for hot tea when clicked
                            new DialogInterface.OnClickListener() {

                                @Override
                                public void onClick(DialogInterface arg0, int arg1) {
                                    Intent i = new Intent(StartingFragment.this.getActivity(),
                                            OolongTeaActivity.class);
                                    StartingFragment.this.getActivity().startActivity(i);
                                }
                            });

                    oolongBuilder.setNeutralButton("Iced",

                            new DialogInterface.OnClickListener() {

                                @Override
                                public void onClick(DialogInterface dialog, int which) {
                                    Intent i = new Intent(StartingFragment.this.getActivity(),
                                            ColdOolongTeaActivity.class);
                                    StartingFragment.this.getActivity().startActivity(i);

                                }
                            });

                    oolongBuilder.setTitle("Oolong Tea");
                    oolongBuilder.setMessage("How Do You Like Your Tea?");

                    AlertDialog oolongDialog = oolongBuilder.create();
                    oolongDialog.show();

                    COUNT++;
                    Fragment fragment = new Fragment();
                    final Bundle bundle = new Bundle();
                    bundle.putString("id_User", String.valueOf(COUNT));
                    Log.i("BUNDLE", bundle.toString());
                    fragment.setArguments(bundle);

                    break;

And the Fragment to which I want the valueOf(integer) to go.

public class TeaCounterFragment extends Fragment {

    public TeaCounterFragment() {

    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

        View rootView = inflater.inflate(R.layout.fragment_tea_counter, container, false);

        TextView oolongCounterText = (TextView) rootView.findViewById(R.id.counter_tv);

        Bundle args = getArguments();
        if (args  != null && args.containsKey("id_User")){
            String userId = args.getString("id_User");
            oolongCounterText.setText(userId);
        }

        return rootView;
    }

I've realized that the TextView will set back to its original state, but if I can at least get it to update after a button click, then I can figure out how to save it permanently at a later time.

I've looked at the Android developer documentation, and it does say that two Fragments should not communicate directly, but I don't see why the method I'm using right now shouldn't work.

EDIT: Attempted another way of solving this problem, but I get a NullPointerException. I decided to create an interface in one Fragment, and through the NavDrawer (MainActivity) class, I tried to update the TextView.

pastebin.com/1dx5rEVv (MainActivity) --- pastebin.com/7wKW1zq1 (StartingFragment)

At this point, I just want to update the TextView (and keep it even after the app is closed completely) using either approach, or an approach that hasn't already been used.

Answer 1

You can easily pass Data by using a Variable in Parent Activity of Fragments. Make that variable as static

public static Bundle myBundle = new Bundle();

Now update it from first fragment as

 YourParentActivityName.myBundle.putString("id_User", String.valueOf(COUNT));

Now in Second fragment you can get this value by

String myValue = YourParentActivityName.myBundle.get("id_User");

Answer 2

I think the problem why your "TextView will set back to its original state" is that overtime the button is clicked, you instantiate a new TeaCounterFragment.

On your First Fragment, create a TeaCounterFragment and instantiate it on your onCreate function.

public class YourFirstFragment extends Fragment {

    private TeaCounterFragment mTeaCounterFragment;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        if (savedInstanceState == null) {
            mTeaCounterFragment = new TeaCounterFragment();
            getFragmentManager().beginTransaction()
                    .add(R.id.container, mTeaCounterFragment)
                    .commit();
        }
    }
}

And on the onClick of the first fragment, just add this on your desired update on the TeaCounterFragment.

@Override
public void onClick(View view) {
    ...
    COUNT++;
    mTeaCounterFragment.UpdateCount(COUNT);
    ...
}

On the TeaCounterFragment, create a public function to update your UI and modify your onCreateView with this.

public class TeaCounterFragment extends Fragment {

    private TextView mTeaCounterText;

    public TeaCounterFragment() {

    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

        View rootView = inflater.inflate(R.layout.fragment_tea_counter, container, false);
        mTeaCounterText = (TextView) rootView.findViewById(R.id.counter_tv);
        return rootView;
    }

    public void UpdateCount(int count)
    {
        mTeaCounterText.setText(String.valueOf(count));
    }
}

Hope this solves your problem.

Answer 3

You are creating an object of Fragment Class. You need to create of TeaCounterFragment class.

        TeaCounterFragment fragment = new TeaCounterFragment ();
        final Bundle bundle = new Bundle();
        bundle.putString("id_User", String.valueOf(COUNT));
        Log.i("BUNDLE", bundle.toString());
        fragment.setArguments(bundle);

Another mistake might be you are not using this created fragment object to present your view. Ensure you are using the same instance to present the view.

Answer 4

After defining an interface in the Fragment class, you also need to make sure the interface is implemented by the activity using the onAttach method in your fragment like this:

@Override
public void onAttach(Activity activity) {
    super.onAttach(activity);
    try {
        listener = (updateFragment) activity;
    } catch (ClassCastException e) {
        throw new ClassCastException(activity.toString()
                + " must implement the interface");
    }
}

Then, to update the fragment from your activity, do this:

@Override
public void onButtonClick(String message) {

TeaCounterFragment fragment = new TeaCounterFragment();
final Bundle bundle = new Bundle();
bundle.putString("id_User", String.valueOf(COUNT));
Log.i("BUNDLE", bundle.toString());
fragment.setArguments(bundle);

FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.fragment_replace, fragment);
transaction.addToBackStack(null);
transaction.commit();
}