Android: Error: must implement OnFragmentInteractionListener

Question

I am getting runtime error : must implement OnFragmentInteractionListener

This is my fragment class file which renders two tabs, tab1 and tab2:

package com.ercess.ercess_app;

import android.net.Uri;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.support.annotation.Nullable;
import android.view.View;
import android.view.ViewGroup;
import android.os.Bundle;
import android.support.design.widget.TabLayout;
import android.support.v4.view.ViewPager;
import android.widget.TableLayout;

public class MyEventsFragment extends Fragment implements Tab1.OnFragmentInteractionListener,Tab2.OnFragmentInteractionListener{

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

        TabLayout tabLayout = v.findViewById(R.id.tablayout);
        tabLayout.addTab(tabLayout.newTab().setText("Tab 1"));
        tabLayout.addTab(tabLayout.newTab().setText("Tab 2"));
        //tabLayout.addTab(tabLayout.newTab().setText("Tab 3"));
        tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);

        final ViewPager viewPager = v.findViewById(R.id.pager);
        final PagerAdapter adapter = new PagerAdapter(getFragmentManager(),tabLayout.getTabCount());
        viewPager.setAdapter(adapter);
        viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));

        tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                viewPager.setCurrentItem(tab.getPosition());
            }

            @Override
            public void onTabUnselected(TabLayout.Tab tab) {

            }

            @Override
            public void onTabReselected(TabLayout.Tab tab) {

            }
        });

        return v;
    }


    @Override
    public void onFragmentInteraction(Uri uri) {

    }
}

This is the java code for tab1 which I want to render from the fragment:

package com.ercess.ercess_app;

import android.net.Uri;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.support.annotation.Nullable;
import android.view.View;
import android.view.ViewGroup;
import android.os.Bundle;
import android.support.design.widget.TabLayout;
import android.support.v4.view.ViewPager;
import android.widget.TableLayout;

public class MyEventsFragment extends Fragment implements Tab1.OnFragmentInteractionListener,Tab2.OnFragmentInteractionListener{

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

        TabLayout tabLayout = v.findViewById(R.id.tablayout);
        tabLayout.addTab(tabLayout.newTab().setText("Tab 1"));
        tabLayout.addTab(tabLayout.newTab().setText("Tab 2"));
        //tabLayout.addTab(tabLayout.newTab().setText("Tab 3"));
        tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);

        final ViewPager viewPager = v.findViewById(R.id.pager);
        final PagerAdapter adapter = new PagerAdapter(getFragmentManager(),tabLayout.getTabCount());
        viewPager.setAdapter(adapter);
        viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));

        tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                viewPager.setCurrentItem(tab.getPosition());
            }

            @Override
            public void onTabUnselected(TabLayout.Tab tab) {

            }

            @Override
            public void onTabReselected(TabLayout.Tab tab) {

            }
        });

        return v;
    }


    @Override
    public void onFragmentInteraction(Uri uri) {

    }
}

This is my logcat:

09-11 18:05:15.231 6765-6765/? E/libprocessgroup: failed to make and chown /acct/uid_10060: Read-only file system
09-11 18:09:40.144 6765-6765/com.ercess.ercess_app **E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.ercess.ercess_app, PID: 6765
    java.lang.RuntimeException: com.ercess.ercess_app.Welcome@3c6aa0fb must implement OnFragmentInteractionListener
        at com.ercess.ercess_app.Tab1.onAttach(Tab1.java:83)**
        at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1404)
        at android.support.v4.app.FragmentTransition.addToFirstInLastOut(FragmentTransition.java:1195)
        at android.support.v4.app.FragmentTransition.calculateFragments(FragmentTransition.java:1078)
        at android.support.v4.app.FragmentTransition.startTransitions(FragmentTransition.java:117)
        at android.support.v4.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2408)
        at android.support.v4.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManager.java:2366)
        at android.support.v4.app.FragmentManagerImpl.execSingleAction(FragmentManager.java:2243)
        at android.support.v4.app.BackStackRecord.commitNowAllowingStateLoss(BackStackRecord.java:654)
        at android.support.v4.app.FragmentStatePagerAdapter.finishUpdate(FragmentStatePagerAdapter.java:168)
        at android.support.v4.view.ViewPager.populate(ViewPager.java:1244)
        at android.support.v4.view.ViewPager.populate(ViewPager.java:1092)
        at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1622)
        at android.view.View.measure(View.java:17547)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5535)
        at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436)
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:722)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:613)
        at android.view.View.measure(View.java:17547)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5535)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:436)
        at android.view.View.measure(View.java:17547)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5535)
        at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436)
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:722)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:613)
        at android.view.View.measure(View.java:17547)
        at android.support.v4.widget.DrawerLayout.onMeasure(DrawerLayout.java:1119)
        at android.view.View.measure(View.java:17547)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5535)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:436)
        at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:143)
        at android.view.View.measure(View.java:17547)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5535)
        at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436)
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:722)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:613)
        at android.view.View.measure(View.java:17547)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5535)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:436)
        at android.view.View.measure(View.java:17547)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5535)
        at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436)
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:722)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:613)
        at android.view.View.measure(View.java:17547)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5535)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:436)
        at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2615)
        at android.view.View.measure(View.java:17547)
        at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2015)
        at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1173)
        at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1379)
        at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1061)
        at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootIm

Answer 1

I was having the exact same problem, then i figured what was wrong. I forgot to uncheck include fragment fancy methods and and include interface callbacks while creating one of the tabs. You might have done the same

Answer 2

It would be better to make your calling activity implement these interfaces. Right now EventsFragment is a... fragment. Fragments should not communicate directly.

All Fragment-to-Fragment communication is done either through a shared ViewModel or through the associated Activity. Two Fragments should never communicate directly.

More info: https://developer.android.com/training/basics/fragments/communicating

Answer 3

When implements an interface, you must override the function defined in the interface, so check the Tab1 class file to find the function signature and override it in your MyEventsFragment file

Or you could press alt + enter when cursor in Tab1.OnFragmentInteractionListener,Tab2.OnFragmentInteractionListener, IDE(android studio )will prompt for you how to do.