Why SQLite handling has to happen on activity or service class?

Question

I am looking for a way to openOrCreateDatabase from another non-activity class and all tutorials and SO questions I found so far, are against that.

Why?

Method openOrCreateDatabase can be called only from Service or Activity or I can call it as a static method SQLiteDatabase.openOrCreateDatabase.

However, this method's second parameter, requires CursorFactory, which in most tutorials is: MODE_PRIVATE. I can't use MODE_PRIVATE from a non-activity class. Some suggest to use context.MODE_PRIVATE, but I wanted to avoid such dependency of passing a context from every activity that I want to use the DB.

What is the best way to have only one DB connection and DB handling in one class across all activities?

what doesn;t work? see https://docs.oracle.com/javase/tutorial/java/javaOO/classvars.html — pskink, Mar 06 '16 at 12:10
If I do this: SQLiteHandler.MODE_PRIVATE it says it is undefined... — Ondrej Tokar, Mar 06 '16 at 12:11
Anyway maybe you understood my question wrong, I was asking what is the right way to access database from a centralized data layer... — Ondrej Tokar, Mar 06 '16 at 12:12
`SQLiteDatabase.openOrCreateDatabase()` requires `String path` / `File file` and `SQLiteDatabase.CursorFactory factory`, there is no `int` parameter like `MODE_*` — pskink, Mar 06 '16 at 12:16
Just take a look at this: http://www.codeproject.com/Articles/783073/A-Simple-Android-SQLite-Example the first code paragraph. — Ondrej Tokar, Mar 06 '16 at 12:20

score 2 · Accepted Answer · edited May 23 '17 at 12:00

Do you access your SQLiteDatabase through a singleton?

private static DatabaseHelper sInstance = null;

public static synchronized DatabaseHelper getInstance(Context context) {

    if (sInstance == null) {
        sInstance = new DatabaseHelper(context.getApplicationContext());
    }
    return sInstance;
 }

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

If so, then the above still requires a Context argument, but if you're averse to passing one around then you can use this technique:

public class App extends Application {

    private static App instance;

    public static App get() { 
        return instance; 
    }

    @Override
    public void onCreate() {
        super.onCreate();
        instance = this;
    }
}

So you could access your database with DatabaseHelper.getInstance(App.get());

That is what I decided to use few minutes ago, great, thank you :) — Ondrej Tokar, Mar 06 '16 at 12:37

Why SQLite handling has to happen on activity or service class?

1 Answers1