打开和关闭SqliteDatabase

Question

I'm moving from java to android development. Previously I worked on Hybernates in java. So android sqlite database handling is bit confusing me. I'm using a singleton database helper class and created methods for opening and closing daabase inside my helper class itself like as follows...

public class DatabaseManager extends SQLiteOpenHelper {
 private static DatabaseManager instance;
 public static DatabaseManager getInstance(Context context) {
    if (instance == null)
        instance = new DatabaseManager(context);
    return instance;
}
public static DatabaseManager getInstance() {
    return instance;
}
 @Override
public void onCreate(SQLiteDatabase db) {
    //CREATING TABLES...
}
 public SQLiteDatabase getReadableDatabase(String logMsg) {
    Log.d(TAG, "Readable database opening from :" + logMsg);
    return super.getReadableDatabase();
}

public SQLiteDatabase getWritableDatabase(String logMsg) {
    Log.d(TAG, "Writable database opening from :" + logMsg);
    return super.getWritableDatabase();
}

public void closeDb(SQLiteDatabase db, String logMsg) {
    db.close();
    Log.d(TAG, "Closing db from :" + logMsg);
}
}

Now my situation I'm working on a messaging application. In that there will be some listeners running back, they insert/retrieve data inside one of those tables of application's db. And I'm planning in my activity to use a content provider to load listview with ResourceCursorAdapter from messages table. If I open and close database during background and in activity(onResume,onPause) will it cause in problems? If this is not the right approach how should i handle this situation? Thanks in advance....

Answer 1

It's best not to keep the database open for too long. As many of the lifecycle events may or may not occur, it's best to just open the database when needed, do all the operations in the database and close immediately.

Therefore you don't really need the 3 last methods in your class unless you're planning to use them to centralise some other operations (like you did with logging).