db

public class NotesAdapter extends RecyclerView.Adapter<NotesAdapter.MyViewHolder> {

    private Context context;
    private List<Note> notesList;

    public class MyViewHolder extends RecyclerView.ViewHolder {
        public TextView note;
        public TextView dot;
        public TextView timestamp;

        public MyViewHolder(View view) {
            super(view);
            note = view.findViewById(R.id.note);
            dot = view.findViewById(R.id.dot);
            timestamp = view.findViewById(R.id.timestamp);
        }
    }


    public NotesAdapter(Context context, List<Note> notesList) {
        this.context = context;
        this.notesList = notesList;
    }

    @Override
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View itemView = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.note_list_row, parent, false);

        return new MyViewHolder(itemView);
    }

    @Override
    public void onBindViewHolder(MyViewHolder holder, int position) {
        Note note = notesList.get(position);

        holder.note.setText(note.getNote());

        // Displaying dot from HTML character code
        holder.dot.setText(Html.fromHtml("&#8226;"));

        // Formatting and displaying timestamp
        holder.timestamp.setText(formatDate(note.getTimestamp()));
    }

    @Override
    public int getItemCount() {
        return notesList.size();
    }

    /**
     * Formatting timestamp to `MMM d` format
     * Input: 2018-02-21 00:15:42
     * Output: Feb 21
     */
    private String formatDate(String dateStr) {
        try {
            SimpleDateFormat fmt = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
            Date date = fmt.parse(dateStr);
            SimpleDateFormat fmtOut = new SimpleDateFormat("MMM d");
            return fmtOut.format(date);
        } catch (ParseException e) {

        }

        return "";
    }
}
////////////////////////////////////////////////////////////////////
MainActivity main;

main.db.somequery;
////////////////////Dbhelper////////
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

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

import info.androidhive.sqlite.database.model.Note;

public class DatabaseHelper extends SQLiteOpenHelper {

    // Database Version
    private static final int DATABASE_VERSION = 1;

    // Database Name
    private static final String DATABASE_NAME = "notes_db";


    public DatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    // Creating Tables
    @Override
    public void onCreate(SQLiteDatabase db) {

        // create notes table
        db.execSQL(Note.CREATE_TABLE);
    }

    // Upgrading database
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // Drop older table if existed
        db.execSQL("DROP TABLE IF EXISTS " + Note.TABLE_NAME);

        // Create tables again
        onCreate(db);
    }

    public long insertNote(String note) {
        // get writable database as we want to write data
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();
        // `id` and `timestamp` will be inserted automatically.
        // no need to add them
        values.put(Note.COLUMN_NOTE, note);

        // insert row
        long id = db.insert(Note.TABLE_NAME, null, values);

        // close db connection
        db.close();

        // return newly inserted row id
        return id;
    }

    public Note getNote(long id) {
        // get readable database as we are not inserting anything
        SQLiteDatabase db = this.getReadableDatabase();

        Cursor cursor = db.query(Note.TABLE_NAME,
                new String[]{Note.COLUMN_ID, Note.COLUMN_NOTE, Note.COLUMN_TIMESTAMP},
                Note.COLUMN_ID + "=?",
                new String[]{String.valueOf(id)}, null, null, null, null);

        if (cursor != null)
            cursor.moveToFirst();

        // prepare note object
        Note note = new Note(
                cursor.getInt(cursor.getColumnIndex(Note.COLUMN_ID)),
                cursor.getString(cursor.getColumnIndex(Note.COLUMN_NOTE)),
                cursor.getString(cursor.getColumnIndex(Note.COLUMN_TIMESTAMP)));

        // close the db connection
        cursor.close();

        return note;
    }

    public List<Note> getAllNotes() {
        List<Note> notes = new ArrayList<>();

        // Select All Query
        String selectQuery = "SELECT  * FROM " + Note.TABLE_NAME + " ORDER BY " +
                Note.COLUMN_TIMESTAMP + " DESC";

        SQLiteDatabase db = this.getWritableDatabase();
        Cursor cursor = db.rawQuery(selectQuery, null);

        // looping through all rows and adding to list
        if (cursor.moveToFirst()) {
            do {
                Note note = new Note();
                note.setId(cursor.getInt(cursor.getColumnIndex(Note.COLUMN_ID)));
                note.setNote(cursor.getString(cursor.getColumnIndex(Note.COLUMN_NOTE)));
                note.setTimestamp(cursor.getString(cursor.getColumnIndex(Note.COLUMN_TIMESTAMP)));

                notes.add(note);
            } while (cursor.moveToNext());
        }

        // close db connection
        db.close();

        // return notes list
        return notes;
    }

    public int getNotesCount() {
        String countQuery = "SELECT  * FROM " + Note.TABLE_NAME;
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery(countQuery, null);

        int count = cursor.getCount();
        cursor.close();


        // return count
        return count;
    }

    public int updateNote(Note note) {
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();
        values.put(Note.COLUMN_NOTE, note.getNote());

        // updating row
        return db.update(Note.TABLE_NAME, values, Note.COLUMN_ID + " = ?",
                new String[]{String.valueOf(note.getId())});
    }

    public void deleteNote(Note note) {
        SQLiteDatabase db = this.getWritableDatabase();
        db.delete(Note.TABLE_NAME, Note.COLUMN_ID + " = ?",
                new String[]{String.valueOf(note.getId())});
        db.close();
    }
}
////////////////////////////////////////adapter
public class NotesAdapter extends RecyclerView.Adapter<NotesAdapter.MyViewHolder> {

    private Context context;
    private List<Note> notesList;

    public class MyViewHolder extends RecyclerView.ViewHolder {
        public TextView note;
        public TextView dot;
        public TextView timestamp;

        public MyViewHolder(View view) {
            super(view);
            note = view.findViewById(R.id.note);
            dot = view.findViewById(R.id.dot);
            timestamp = view.findViewById(R.id.timestamp);
        }
    }


    public NotesAdapter(Context context, List<Note> notesList) {
        this.context = context;
        this.notesList = notesList;
    }

    @Override
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View itemView = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.note_list_row, parent, false);

        return new MyViewHolder(itemView);
    }

    @Override
    public void onBindViewHolder(MyViewHolder holder, int position) {
        Note note = notesList.get(position);

        holder.note.setText(note.getNote());

        // Displaying dot from HTML character code
        holder.dot.setText(Html.fromHtml("&#8226;"));

        // Formatting and displaying timestamp
        holder.timestamp.setText(formatDate(note.getTimestamp()));
    }

    @Override
    public int getItemCount() {
        return notesList.size();
    }

    /**
     * Formatting timestamp to `MMM d` format
     * Input: 2018-02-21 00:15:42
     * Output: Feb 21
     */
    private String formatDate(String dateStr) {
        try {
            SimpleDateFormat fmt = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
            Date date = fmt.parse(dateStr);
            SimpleDateFormat fmtOut = new SimpleDateFormat("MMM d");
            return fmtOut.format(date);
        } catch (ParseException e) {

        }

        return "";
    }
}