Sending Data From Fragment to Fragment Using TabLayout

Question

I've been having difficulties sending data from one fragment to another when utilizing a TabLayout. I've read copious amounts of online posts pertaining to how to do this and have had no success when implementing them myself.

I have four fragments set up in my application. I'm trying to send data gathered from an EditText element in the fourth fragment to the TextView element of the second fragment.

I don't get any errors, but the text does not show up in the second fragment. I don't know how to proceed from here. Thanks!

Fourth Fragment (sending Fragment)

public class settings extends Fragment {
    SendMessage SM;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View rootView = inflater.inflate(
                R.layout.setl, container, false);
        return rootView;


    }

    @Override
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        Button btnPassData = (Button) view.findViewById(R.id.btnPassData);
        final EditText inData = (EditText) view.findViewById(R.id.inMessage);
        btnPassData.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                SM.sendData(inData.getText().toString().trim());
            }
        });

    }

    public interface SendMessage {
        void sendData(String message);
    }

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);

        try {
            SM = (SendMessage) getActivity();
        } catch (ClassCastException e) {
            throw new ClassCastException("Error in retrieving data. Please try again");
        }
    }
}

Second Fragment (receiving fragment)

public class tt extends Fragment {

    TextView txtData;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View rootView = inflater.inflate(
                R.layout.ttl, container, false);

        return rootView;



    }

    @Override
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        txtData = (TextView)view.findViewById(R.id.txtData);


    }

    public void displayReceivedData(String message) {
        txtData.setText("Data received: "+ message);

    }
}

Main Activity

public class MainActivity extends AppCompatActivity implements settings.SendMessage {

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        getWindow().setFlags(WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS, WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS);
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main_test);
        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 sendData(String message) {
        String tag = "android:switcher:" + R.id.view_pager + ":" + 1;
        tt f = (tt) getSupportFragmentManager().findFragmentByTag(tag);
        f.displayReceivedData(message);
    }
}

Answer 1

Something might be breaking in other part of your app.

Below is code of your working example.

class MainActivity

public class MainActivity extends AppCompatActivity implements Setting.SendMessage {

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        getWindow().setFlags(WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS, WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS);
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        SectionsPagerAdapter sectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager(),this );
        ViewPager viewPager = findViewById(R.id.viewpager);
        viewPager.setAdapter(sectionsPagerAdapter);
        TabLayout tabs = findViewById(R.id.sliding_tabs);
        tabs.setupWithViewPager(viewPager);
    }

    @Override
    public void sendData(String message) {
        String tag = "android:switcher:" + R.id.viewpager + ":" + 1;
        tt f = (tt) getSupportFragmentManager().findFragmentByTag(tag);
        f.displayReceivedData(message);
    }
}

class Setting

 public class Setting extends Fragment {
        SendMessage SM;
        @Nullable
        @Override
        public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
            View rootView = inflater.inflate(
                    R.layout.setl, container, false);
            return rootView;
        }

        @Override
        public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
            super.onViewCreated(view, savedInstanceState);

            Button btnPassData = (Button) view.findViewById(R.id.btnPassData);
            final EditText inData = (EditText) view.findViewById(R.id.inMessage);
            btnPassData.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    SM.sendData(inData.getText().toString().trim());
                }
            });

        }
        public interface SendMessage {
            void sendData(String message);
        }

        @Override
        public void onAttach(Context context) {
            super.onAttach(context);
            try {
                SM = (SendMessage) getActivity();
            } catch (ClassCastException e) {
                throw new ClassCastException("Error in retrieving data. Please try again");
            }
        }
    }

class tt

public class tt extends Fragment {

    TextView txtData;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View rootView = inflater.inflate(
                R.layout.tt, container, false);
        return rootView;
    }

    @Override
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        txtData = (TextView)view.findViewById(R.id.txtData);
    }

    public void displayReceivedData(String message) {
        txtData.setText("Data received: "+ message);

    }
}

class SectionsPagerAdapter

public class SectionsPagerAdapter  extends FragmentPagerAdapter {
    final int PAGE_COUNT = 2;
    private String tabTitles[] = new String[] { "Tab1", "Tab2"};
    private Context context;

    public SectionsPagerAdapter(FragmentManager fm, Context context) {
        super(fm);
        this.context = context;
    }

    @Override
    public int getCount() {
        return PAGE_COUNT;
    }

    @Override
    public Fragment getItem(int position) {
        if(position==0){
            return new Setting();
        }
        else
            return new tt();
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return tabTitles[position];
    }
}