Main

package com.bertho.gmyl;


import android.os.Bundle;
import android.support.design.widget.TabLayout;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;

import com.bertho.gmyl.fragments.EngagedFragment;
import com.bertho.gmyl.fragments.RequestFragment;
import com.bertho.gmyl.fragments.SigninFragment;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity implements EngagedFragment.SubmitListener {

    private static final String TAG = MainActivity.class.getSimpleName();

    private Toolbar toolbar;
    private TabLayout tabLayout;
    private ViewPager viewPager;
    ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.engine_main);

        toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        //getSupportActionBar().setDisplayHomeAsUpEnabled(true);

        viewPager = (ViewPager) findViewById(R.id.viewpager);

        setupViewPager(viewPager);

        tabLayout = (TabLayout) findViewById(R.id.tabs);
        tabLayout.setupWithViewPager(viewPager);
    }

    private void setupViewPager(ViewPager viewPager) {
        adapter.addFrag(new SigninFragment(), "SIGN-IN");
        adapter.addFrag(new EngagedFragment(), "ENGAGED ID");
        adapter.addFrag(new RequestFragment(), "LOCATION");
        viewPager.setAdapter(adapter);
    }

    @Override
    public void onSubmit() {
        if(viewPager != null && viewPager.getCurrentItem() == 2){

            if(adapter != null){
                Fragment fragment = adapter.getItem(viewPager.getCurrentItem());
                if(fragment != null){
                    RequestFragment requestFragment = (RequestFragment) fragment;
                    requestFragment.setRecyclerView();
                }
            }
        }
    }

    class ViewPagerAdapter extends FragmentPagerAdapter {
        private final List<Fragment> mFragmentList = new ArrayList<>();
        private final List<String> mFragmentTitleList = new ArrayList<>();

        public ViewPagerAdapter(FragmentManager manager) {
            super(manager);
        }

        @Override
        public Fragment getItem(int position) {
            return mFragmentList.get(position);
        }

        @Override
        public int getCount() {
            return mFragmentList.size();
        }

        public void addFrag(Fragment fragment, String title) {
            mFragmentList.add(fragment);
            mFragmentTitleList.add(title);
            viewPager.setAdapter(adapter);
        }

        @Override
        public CharSequence getPageTitle(int position) {
            return mFragmentTitleList.get(position);
        }
    }

}