Original Java code for the Main Activity of Data Jacket. The current version uses Kotlin instead.

MainActvityDataJacket.java

package com.marlonjones.datajacketapp;

import android.content.Intent;
import android.support.design.widget.TabLayout;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;

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.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;

import android.widget.TextView;

import com.afollestad.materialdialogs.MaterialDialog;

public class MainActivity extends AppCompatActivity {

    private SectionsPagerAdapter mSectionsPagerAdapter;

    private ViewPager mViewPager;
    private final String[] mTabsTitle = {"ADDED", "ALL APPS"};

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main_normal);
        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
        mViewPager = findViewById(R.id.container);
        mViewPager.setAdapter(mSectionsPagerAdapter);
        TabLayout tabLayout = findViewById(R.id.tabs);
        tabLayout.setupWithViewPager(mViewPager);

    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        int id = item.getItemId();

        if (id == R.id.action_settings) {
            Intent settingsIntent = new Intent (this, SettingsActivity.class);
            startActivity(settingsIntent);
        }
        if (id == R.id.action_about){
            new MaterialDialog.Builder(this)
                    .title(R.string.about)
                    .content(R.string.about_contents)
                    .positiveText(R.string.dismiss)
                    .show();
        }
        return super.onOptionsItemSelected(item);
    }


    public static class PlaceholderFragment extends Fragment {

        private static final String ARG_SECTION_NUMBER = "section_number";

        public PlaceholderFragment() {
        }


        public static PlaceholderFragment newInstance(int sectionNumber) {
            PlaceholderFragment fragment = new PlaceholderFragment();
            Bundle args = new Bundle();
            args.putInt(ARG_SECTION_NUMBER, sectionNumber);
            fragment.setArguments(args);
            return fragment;
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
            View rootView = inflater.inflate(R.layout.fragment_main, container, false);
            TextView textView = rootView.findViewById(R.id.section_label);
            textView.setText(getString(R.string.section_format, getArguments().getInt(ARG_SECTION_NUMBER)));
            return rootView;
        }
    }


    public class SectionsPagerAdapter extends FragmentPagerAdapter {

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

        @Override
        public Fragment getItem(int position) {
            switch(position) {
                case 0:
                    return new ItemFragmentSaved();
                case 1:
                    return new AllAppsFragment();
            }
            return null;
        }

        @Override
        public int getCount() {
            return 2;
        }

        @Override
        public CharSequence getPageTitle(int position) {
            switch (position) {
                case 0:
                    return "ADDED";
                case 1:
                    return "ALL APPS"; //If name matches in Added, then grey out that app or remove from list
            }
            return null;
        }
    }
}