Create DataBase in Android using SQL Lite

public class DatabaseHandler extends SQLiteOpenHelper {       // All Static variables     // Database Version     private static final int DATABASE_VERSION = 1;       // Database Name     private static final String DATABASE_NAME = "contactsManager";       // Contacts table name     private static final String TABLE_CONTACTS = "contacts";       // Contacts Table Columns names     private static final String KEY_ID = "id";     private static final String KEY_NAME = "name";     private static final String KEY_PH_NO = "phone_number";       public DatabaseHandler(Context context) {         super(context, DATABASE_NAME, null, DATABASE_VERSION);     }       // Creating Tables     @Override     public void onCreate(SQLiteDatabase db) {         String CREATE_CONTACTS_TABLE = "CREATE TABLE " + TABLE_CONTACTS + "("                 + KEY_ID + " INTEGER PRIMARY KEY," + KEY_NAME + " TEXT,"                 + KEY_PH_NO + " TEXT" + ")";         db.execSQL(CREATE_CONTACTS_TABLE);     }       // Upgrading database     @Override     public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {         // Drop older table if existed         db.execSQL("DROP TABLE IF EXISTS " + TABLE_CONTACTS);           // Create tables again         onCreate(db);     }       /**      * All CRUD(Create, Read, Update, Delete) Operations      */       // Adding new contact     void addContact(Contact contact) {         SQLiteDatabase db = this.getWritableDatabase();           ContentValues values = new ContentValues();         values.put(KEY_NAME, contact.getName()); // Contact Name         values.put(KEY_PH_NO, contact.getPhoneNumber()); // Contact Phone           // Inserting Row         db.insert(TABLE_CONTACTS, null, values);         db.close(); // Closing database connection     }       // Getting single contact     Contact getContact(int id) {         SQLiteDatabase db = this.getReadableDatabase();           Cursor cursor = db.query(TABLE_CONTACTS, new String[] { KEY_ID,                 KEY_NAME, KEY_PH_NO }, KEY_ID + "=?",                 new String[] { String.valueOf(id) }, null, null, null, null);         if (cursor != null)             cursor.moveToFirst();           Contact contact = new Contact(Integer.parseInt(cursor.getString(0)),                 cursor.getString(1), cursor.getString(2));         // return contact         return contact;     }       // Getting All Contacts     public List getAllContacts() {         List contactList = new ArrayList();         // Select All Query         String selectQuery = "SELECT  * FROM " + TABLE_CONTACTS;           SQLiteDatabase db = this.getWritableDatabase();         Cursor cursor = db.rawQuery(selectQuery, null);           // looping through all rows and adding to list         if (cursor.moveToFirst()) {             do {                 Contact contact = new Contact();                 contact.setID(Integer.parseInt(cursor.getString(0)));                 contact.setName(cursor.getString(1));                 contact.setPhoneNumber(cursor.getString(2));                 // Adding contact to list                 contactList.add(contact);             } while (cursor.moveToNext());         }           // return contact list         return contactList;     }       // Updating single contact     public int updateContact(Contact contact) {         SQLiteDatabase db = this.getWritableDatabase();           ContentValues values = new ContentValues();         values.put(KEY_NAME, contact.getName());         values.put(KEY_PH_NO, contact.getPhoneNumber());           // updating row         return db.update(TABLE_CONTACTS, values, KEY_ID + " = ?",                 new String[] { String.valueOf(contact.getID()) });     }       // Deleting single contact     public void deleteContact(Contact contact) {         SQLiteDatabase db = this.getWritableDatabase();         db.delete(TABLE_CONTACTS, KEY_ID + " = ?",                 new String[] { String.valueOf(contact.getID()) });         db.close();     }       // Getting contacts Count     public int getContactsCount() {         String countQuery = "SELECT  * FROM " + TABLE_CONTACTS;         SQLiteDatabase db = this.getReadableDatabase();         Cursor cursor = db.rawQuery(countQuery, null);         cursor.close();           // return count         return cursor.getCount();     }   }