android singleton helper and read before delete/write

Question

I have singleton database helper to access db. This part has no problem. However, I doubt that async threads of reading and writing/deleting ends up with problem.

If one thread is reading, and the other one is deleting; I am suspicious about reading one cannot read the value before deletion. Can anybody confirm this? And what should be the solution way for achieving this with singleton helper?

Any help is appreciated, thanks

public CategoryDatabaseConnection(Context context) {
        mDbOpenHelper = CategoryDatabaseOpenHelper.getInstance(context, null, null, 0);
        mOpenCounter = mDbOpenHelper.mOpenCounter;
    }

    public void open() throws SQLException {
        // open database in reading/writing mode
        int value = mOpenCounter.incrementAndGet();
         if(value == 1 || mDatabase==null) {
                // Opening new database
             mDatabase = mDbOpenHelper.getWritableDatabase();
            }
    }

this answers your question http://stackoverflow.com/a/3689883/1061944 — Murtaza Khursheed Hussain, Dec 18 '14 at 10:24
@MurtazaHussain well,as far as I examine that one only talks about sync insertions with one helper. I wonder what if one is deleting and the other one is reading — tugce, Dec 18 '14 at 10:58
there is link below on that answer which states about locking. I think you should read it thoroughly. — Murtaza Khursheed Hussain, Dec 18 '14 at 11:00

score 0 · Answer 1 · answered Dec 18 '14 at 11:13

0

You database helper must be synchronized so that only one thread can access it at a time.

To implement synchronization just put keywod synchronized before your class.

Ex.

public static synchronized singletonDBHelper()
{
 // your code
}

answered Dec 18 '14 at 11:13

Vipin Sharma

594
5
19

Yes it is synchronized – tugce Dec 18 '14 at 11:20
you can also set priority of threads. Thread with higher priority will given preference. – Vipin Sharma Dec 18 '14 at 11:25

android singleton helper and read before delete/write

1 Answers1