Updating ListView inside Fragment after String was added to SQLite database from another SearchActivity

Question

I am trying perform the following task:

Basically, one part of my code has a SearchView which accepts a query from the user that is then looked up in a Dictionary class instantiated in my SearchActivity. These words are then stored to an array, which is in turn stored in a database, and then displayed in a ListView on a Fragment class. Everything seems to be working great aside from the fact that, when I return to the original activity (with the emulator's integrated back button), the ListView in the Fragment class is not updated.

However, when I initialize my activity again, the ListView in the Fragment class is indeed up-to-date.

I have tried the popular solutions suggested in this thread ( ViewPager PagerAdapter not updating the View ), but none of them worked. A dodgy partial-solution I attempted was setting a new adapter in each single one of the setOnTabSelectedListener listeners, but that just consumed too many resources and the ListView only updated when I clicked on the TabLayout.

Here is my code, for reference:

BookSwipe.java (this is the activity that manages the Fragments and the TabLayout)

public class BookSwipe extends AppCompatActivity {
TextView tvTitle;
TextView tvAuthor;
WebView wbDescription;
ImageView ivCover;

CustomAdapter adapter;

String bookTitle;

public void startActivity(Intent intent) {
    // check if search intent
    if (Intent.ACTION_SEARCH.equals(intent.getAction())) {
        intent.putExtra("KEY", bookTitle);
    }

    super.startActivity(intent);
}

@Override
protected void onCreate(Bundle savedInstanceState) {
    TabLayout tabLayout;
    final ViewPager viewPager;


    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_book_swipe);


    Bundle bundle = getIntent().getExtras();

    bookTitle = bundle.getString("data");

    System.out.println(bookTitle);

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

    adapter = new CustomAdapter(getSupportFragmentManager(), getActionBar());
    viewPager.setAdapter(adapter);

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


    tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
        @Override
        public void onTabSelected(TabLayout.Tab tab) {

            viewPager.setCurrentItem(tab.getPosition());
            -- viewPager.setAdapter(adapter);

        }

        @Override
        public void onTabUnselected(TabLayout.Tab tab) {
            viewPager.setCurrentItem(tab.getPosition());
            -- viewPager.setAdapter(adapter);
        }

        @Override
        public void onTabReselected(TabLayout.Tab tab) {
            viewPager.setCurrentItem(tab.getPosition());
            -- viewPager.setAdapter(adapter);
        }
    });
}

public boolean onCreateOptionsMenu(Menu menu) {

    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.options_menu, menu);

    SearchManager searchManager =
            (SearchManager) getSystemService(Context.SEARCH_SERVICE);
    SearchView searchView =
            (SearchView) menu.findItem(R.id.search2).getActionView();
    searchView.setSearchableInfo(
            searchManager.getSearchableInfo(getComponentName()));

    return true;

}

public String getBookTitle() {
    return bookTitle;
}

public void setBookTitle(String bookTitle) {
    this.bookTitle = bookTitle;
}


private class CustomAdapter extends FragmentStatePagerAdapter {

    private String[] fragments = {"Information", "Words", "Quotes"};

    public CustomAdapter(FragmentManager supportFragmentManager, ActionBar actionBar) {
        super(supportFragmentManager);
    }

    @Override
    public Fragment getItem(int position) {
        switch (position) {
            case 0:
                return new BookProfileFragment(bookTitle);
            case 1:
                return new BookWordsFragment(bookTitle);
            case 2:
                return new BookQuotesFragment(bookTitle);
            default:
                return null;
        }
    }

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

    @Override
    public CharSequence getPageTitle(int position) {
        return fragments[position];
    }

    @Override
    public int getItemPosition(Object object) {
        return POSITION_NONE;
    }
}

}

SearchActivity.java (this displays the definition of the word)

public class SearchActivity extends AppCompatActivity implements Constants {

TextView dfnDisplay;
private static String LIST_SEPARATOR = "__,__";
public String query;
public String mValue;

MyDBHandler dbHandler;
SQLiteDatabase newDB;

ArrayList stringArray = new ArrayList<>();

Cursor cursor;

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

    dfnDisplay = (TextView) findViewById(R.id.displayDfn);


    handleIntent(getIntent());


}

public void saveBtnAction(View view) {


    stringArray.add(query);
    BookWordsFragment.refreshList(stringArray);
    String sendString = convertListToString(stringArray);
    dbHandler.addWords(mValue, sendString);

}


protected void onNewIntent(Intent intent) {

    handleIntent(intent);
}

private void handleIntent(Intent intent) {

    mValue = intent.getStringExtra("KEY");
    System.out.println(mValue);

    dbHandler = new MyDBHandler(this.getApplicationContext(), null, null, 1);
    newDB = dbHandler.getWritableDatabase();

    String query2 = "SELECT " + COLUMN_WORDS + " FROM " + TABLE_BOOKS + " WHERE " + COLUMN_BOOK_TITLE + "=\"" + mValue + "\"";
    cursor = newDB.rawQuery(query2, null);

    if (cursor.moveToFirst()) {
        while (cursor.isAfterLast() != true) {

            String itemname = cursor.getString(cursor.getColumnIndex("words"));
            System.out.println(itemname);
            if(itemname != null){
                stringArray = (ArrayList) convertStringToList(itemname);
            }

            break;
        }
    }

    if (Intent.ACTION_SEARCH.equals(intent.getAction())) {
        query = intent.getStringExtra(SearchManager.QUERY);
        dfnDisplay.setText(English.processDefinition(query));
        dfnDisplay.setMovementMethod(new ScrollingMovementMethod());
    }
}


public static String convertListToString(List<String> stringList) {
    StringBuffer stringBuffer = new StringBuffer();
    for (String str : stringList) {
        stringBuffer.append(str).append(LIST_SEPARATOR);
    }

    int lastIndex = stringBuffer.lastIndexOf(LIST_SEPARATOR);
    stringBuffer.delete(lastIndex, lastIndex + LIST_SEPARATOR.length() + 1);

    return stringBuffer.toString();
}

public static List<String> convertStringToList(String str) {

    List<String> list = new ArrayList(Arrays.asList(str.split(LIST_SEPARATOR)));

    return list;
} }

BookWordsFragment.java (this is the fragment where the ListView is stored)

public class BookWordsFragment extends Fragment implements Constants {

MyDBHandler dbHandler;
SQLiteDatabase newDB;
Cursor cursor;

public static ArrayAdapter wordListAdapter;
public ListView wordList;

public String bookTitle;

static List<String> stringArray = new ArrayList<>();



public BookWordsFragment() {

}

public BookWordsFragment(String bookTitle){
    this.bookTitle = bookTitle;
}


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {

    View rootView = inflater.inflate(R.layout.fragment_book_words, container, false);


    wordList = (ListView) rootView.findViewById(R.id.savedWordsList);



    stringArray = populateArray();

    wordListAdapter = new CustomListAdapter(getActivity(), R.layout.custom_list, stringArray);
    wordList.setAdapter(wordListAdapter);


    if(!stringArray.isEmpty()){

    }

    wordListAdapter.notifyDataSetChanged();

    return rootView;
}


public List<String> populateArray(){

    List<String> list = new ArrayList();

    dbHandler = new MyDBHandler(this.getActivity(), null, null, 1);
    newDB = dbHandler.getWritableDatabase();

    String query2 = "SELECT " + COLUMN_WORDS + " FROM " + TABLE_BOOKS + " WHERE " + COLUMN_BOOK_TITLE + "=\"" + bookTitle + "\"";
    cursor = newDB.rawQuery(query2, null);

    if (cursor.moveToFirst()) {
        while (cursor.isAfterLast() != true) {

            String itemname = cursor.getString(cursor.getColumnIndex("words"));
            System.out.println("THIS IS : " + itemname);

            if(itemname != null){
                list = SearchActivity.convertStringToList(itemname);
                System.out.println(stringArray);
            }

            break;
        }
    }

    return list;
}

public static void refreshList(ArrayList stringArrayCopy){
    stringArray = stringArrayCopy;
    wordListAdapter.notifyDataSetChanged();
}

@Override
public void onResume() {
    super.onResume();
    wordListAdapter.notifyDataSetChanged();
}

}

Here are some pictures for reference: Displaying the Fragment Displaying the definition in SearchActivity

Thank you very much in advance.

EDIT:

Here is the code for my CustomListAdapter, as requested in the comments

class CustomListAdapter extends ArrayAdapter {

    private Context mContext;
    private int id;
    private List<String> items ;

    public CustomListAdapter(Context context, int textViewResourceId , List<String> list )
    {
        super(context, textViewResourceId, list);
        mContext = context;
        id = textViewResourceId;
        items = list ;
    }

    @Override
    public View getView(int position, View v, ViewGroup parent)
    {
        View mView = v ;
        if(mView == null){
            LayoutInflater vi = (LayoutInflater)mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            mView = vi.inflate(id, null);
        }

        TextView text = (TextView) mView.findViewById(R.id.textView);

        if(items.get(position) != null )
        {
            text.setTextColor(Color.BLACK);
            text.setText(items.get(position));
            text.setTextSize(30);

        }

        return mView;
    }


}

Answer 1

Create a method in your CustomListAdapter class like :

public void setList(ArrayList<String> wordsList) {
    items = wordsList; //items is the list you have as a field in adapter.
    notifyDatasetChanged();
}

In your Fragments onResume() ,

@Override
public void onResume() {
    super.onResume();
    stringArray = populateArray();
    wordListAdapter.setList(stringArray);
}

EDIT :

You have to make a little change in Adapter. Add these below methods :

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

@Override
public String getItem(int position) {
    return items.get(position);
}