DatabaseHelper.java

class DatabaseHelper extends SQLiteOpenHelper {
 /*This Constructor should be private to prevent direct instantiation. */
 private DatabaseHelper(Context context) {
 super(context, DATABASE_NAME, null, DATABASE_VERSION);
 }
/* Here I have created synchronized function which will ensure only one instance of Helper class will exists */
 public static synchronized DatabaseHelper getInstance(Context context) {
 // pass application context here
 if (sInstance == null) {
 sInstance = new DatabaseHelper(context.getApplicationContext());
 } return sInstance; }
//Call following function if you want to enable foreign key support
 /* @Override
 public void onConfigure(SQLiteDatabase db) {
 super.onConfigure(db);
 db.setForeignKeyConstraintsEnabled(true);
 } */
 @Override
 public void onCreate(SQLiteDatabase db) {
 //Create and Execute Create Table Query }
 @Override
 public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
 if (oldVersion != newVersion) {
 /* Drop all old tables and recreate them by calling onCreate(db) */ }}}