Question

I need multiple tables in my application. For this I’ve created separate subclasses of SQLiteOpenHelper to insert/remove/update data for different tables. My question is how can I make sure all these subclasses uses same instance of SQLiteDatabase across the entire code. Though I’ve made each subclass a singleton. However, I couldn’t work around the issue of using a common SQLiteDatabase instance across the entire code.

PS: I don’t want to use a ContentPovider or create a single SQLiteOpenHelper subclass as this would complicate my code.

Answer 1

I don’t really see where you’re struggling at using a common SQLiteOpenHelper. You just have to duplicate what you do for one table ! Create a custom class that extends SQLiteOpenHelper and do the duplication.

public class SQLiteCustomBase extends SQLiteOpenHelper {

    private static final String CREATE_BDD_1 = "CREATE TABLE ...";
    private static final String CREATE_BDD_2 = "CREATE TABLE ...";

    public SQLiteCustomBase(Context context, String name, CursorFactory factory, int version) {
        super(context, name, factory, version);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(CREATE_BDD_1);
        db.execSQL(CREATE_BDD_2);
    }

    @Override
    public void onOpen(SQLiteDatabase db) {}

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE " + Vars.TABLE_1 + ";");
        db.execSQL("DROP TABLE " + Vars.TABLE_2 + ";");
        onCreate(db);
    }
}

and then in the class where you perform some database actions :

public class HandlerClass {
    private SQLiteDatabase db;
    private SQLiteCustomBase customBase;

    public HandlerClass(Context context){
        customBase = new SQLiteCustomBase(context, Vars.NAME_DB, null, Vars.VERSION_DB);
    }

    public void open(){
        db = customBase.getWritableDatabase();
    }

    public void openForRead(){
        db = customBase.getReadableDatabase();
    }

    public void close(){
        db.close();
    }

    public SQLiteDatabase getDB(){
        return db;
    }
}

void myMethods()
{
    bdd.insert(Vars.TABLE_1, null, values);
    bdd.insert(Vars.TABLE_2, null, values);
}
etc.