How to implement RecyclerView with CardView rows in a Fragment with TabLayout

问题:

I would like to implement a ListFragment in an Activity that uses a TabLayout, so that I can swipe between the different lists. In the end it should become a booking application so that you can choose between different disciplines and book a certain time slot withing it. However so far I only achieve to do either a ListActivity OR the tabbed activity (the standard one from android studio) but not both. Would be glad if someone could help on this. The tabbed activity:

public class Diciplines extends AppCompatActivity {      /**      * The {@link android.support.v4.view.PagerAdapter} that will provide      * fragments for each of the sections. We use a      * {@link FragmentPagerAdapter} derivative, which will keep every      * loaded fragment in memory. If this becomes too memory intensive, it      * may be best to switch to a      * {@link android.support.v4.app.FragmentStatePagerAdapter}.      */     private SectionsPagerAdapter mSectionsPagerAdapter;      /**      * The {@link ViewPager} that will host the section contents.      */     private ViewPager mViewPager;      @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_diciplines);          Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);         setSupportActionBar(toolbar);         // Create the adapter that will return a fragment for each of the three         // primary sections of the activity.         mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());          // Set up the ViewPager with the sections adapter.         mViewPager = (ViewPager) findViewById(R.id.container);         mViewPager.setAdapter(mSectionsPagerAdapter);           FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);         fab.setOnClickListener(new View.OnClickListener() {             @Override             public void onClick(View view) {                 Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)                         .setAction("Action", null).show();             }         });      }       @Override     public boolean onCreateOptionsMenu(Menu menu) {         // Inflate the menu; this adds items to the action bar if it is present.         getMenuInflater().inflate(R.menu.menu_diciplines, menu);         return true;     }      @Override     public boolean onOptionsItemSelected(MenuItem item) {         // Handle action bar item clicks here. The action bar will         // automatically handle clicks on the Home/Up button, so long         // as you specify a parent activity in AndroidManifest.xml.         int id = item.getItemId();          //noinspection SimplifiableIfStatement         if (id == R.id.action_settings) {             return true;         }          return super.onOptionsItemSelected(item);     }       /**      * A {@link FragmentPagerAdapter} that returns a fragment corresponding to      * one of the sections/tabs/pages.      */     public class SectionsPagerAdapter extends FragmentPagerAdapter {          public SectionsPagerAdapter(FragmentManager fm) {             super(fm);         }          @Override         public Fragment getItem(int position) {             // getItem is called to instantiate the fragment for the given page.             // Return a PlaceholderFragment (defined as a static inner class below).             return PlaceholderFragment.newInstance(position + 1);         }          @Override         public int getCount() {             // Show 3 total pages.             return 3;         }          @Override         public CharSequence getPageTitle(int position) {             switch (position) {                 case 0:                     return "SECTION 1";                 case