Can someone show me a simple working implementation of PagerSlidingTabStrip?

Question

Here is the library: https://github.com/astuetz/PagerSlidingTabStrip I'm trying to implement it but my app keeps crashing on startup. I've tried to understand the sample app that is posted but don't think I'm doing something right. Here is my code:

MainActivity.java

import android.graphics.Color;
import android.graphics.drawable.ColorDrawable;
import android.graphics.drawable.Drawable;
import android.graphics.drawable.LayerDrawable;
import android.graphics.drawable.TransitionDrawable;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.util.TypedValue;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;

import com.astuetz.PagerSlidingTabStrip;


public class MainActivity extends FragmentActivity {

    private final Handler handler = new Handler();

    private PagerSlidingTabStrip tabs;
    private ViewPager pager;
    private MyPagerAdapter adapter;

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

        tabs = (PagerSlidingTabStrip) findViewById(R.id.tabs);
        pager = (ViewPager) findViewById(R.id.pager);
        adapter = new MyPagerAdapter(getSupportFragmentManager());

        pager.setAdapter(adapter);

        tabs.setViewPager(pager);
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, 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();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    @Override
    protected void onSaveInstanceState(Bundle outState){
        super.onSaveInstanceState(outState);
    }
    @Override
    protected void onRestoreInstanceState(Bundle savedInstanceState){
        super.onRestoreInstanceState(savedInstanceState);
    }

    private Drawable.Callback drawableCallback = new Drawable.Callback() {
        @Override
        public void invalidateDrawable(Drawable who) {
            getActionBar().setBackgroundDrawable(who);
        }

        @Override
        public void scheduleDrawable(Drawable who, Runnable what, long when) {
            handler.postAtTime(what, when);
        }

        @Override
        public void unscheduleDrawable(Drawable who, Runnable what) {
            handler.removeCallbacks(what);
        }
    };

    public class MyPagerAdapter extends FragmentPagerAdapter{
        private final String[] TITLES = {"T1","T2"};

        public MyPagerAdapter(FragmentManager fm){
            super(fm);
        }

        public CharSequence getPageTitle(int position){
            return TITLES[position];
        }
        @Override
        public Fragment getItem(int i) {
            return null;
        }

        @Override
        public int getCount() {
            return TITLES.length;
        }
    }
}

And here is activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    tools:context="edu.purdue.test.app.MainActivity">

    <com.astuetz.PagerSlidingTabStrip
        android:id="@+id/tabs"
        android:layout_width="match_parent"
        android:layout_height="48dip" />

    <android.support.v4.view.ViewPager
        android:id="@+id/pager"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/tabs"
        tools:context=".MainActivity" />


</RelativeLayout>

Answer 1

You're not instantiating any of the fragments you wish to become tabs in the FragmentPagerAdapter, getItem method. Instead you're returning null and therefore there are no views to fill the viewpager. I can see you've checked out his sample project, maybe take a closer look at the fragments you're trying to add to the viewpager. The above answer looks like a sound implementation.