Android: opening and closing SQLite database

Question

I'm developing and android application in which I often use access the local database. This database can be accessed from differents therads, so I have a coordination problem for the database. I use the following open() and close() method.

public void open(){ 
    mDb=mDbHelper.getWritableDatabase();
}

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

So, usually, when I need to access the db for some operations I open the database, then I perform some operation, and finally I close the database. The code I typically use for this purpose is the following:

    try {
        dbManager.open();
                    // database operation
    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }finally{
        try {
            dbManager.close();
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

But, if for this piece of code is used from differnts threads (supposing thread A and thread B) the following situation may occurs:

A thread: performs open()
B thread: perfroms open()
A thread: perfroms some operation
A thread: performs close()
B thread: try to perform some operation but it fails!

So, the only solution I can guess I to perform open() when my application starts and close() when my application is stopped. I'm not sure that this can be this a good solution?

In effect, the documentation of getWritableDatabase() method (called from my open()) says:

Make sure to call close() when you no longer need the database

So, anyone can suggest me an alternative solution?

don't close db, just close only the cursor to that data – umesh Apr 23 '13 at 14:10 — umesh, Apr 23 '13 at 14:10
synchronize access or do db ops on one thread only – MaciejGórski Apr 23 '13 at 14:15 — MaciejGórski, Apr 23 '13 at 14:15
... or build ContentProvider ... – Selvin Apr 23 '13 at 14:16 — Selvin, Apr 23 '13 at 14:16

score 2 · Accepted Answer · edited May 23 '17 at 12:06

2

You can use the singletone instance and gennerally you can do not close database (but keep transaction closed). There is some information:

Android SQLite DB When to Close

edited May 23 '17 at 12:06

Community

1
1

answered Apr 23 '13 at 15:12

matreshkin

2,199
18
28

score 1 · Answer 2 · answered Apr 23 '13 at 14:25

1

Create a wrapper class, add an atomic integer member and every time you open the database, increment the member, when you close it, decrement the member and if the member is zero, actually close the db.

answered Apr 23 '13 at 14:25

Buda Gavril

21,409
40
127
196

1

no, you will have an atomic integer to know when to really close the db and you will call close on wrapper and inside the wrapper, only if that int is 0 you will actually close the db – Buda Gavril Apr 24 '13 at 06:58

Android: opening and closing SQLite database

2 Answers2

Linked