Android: Cannot perform this operation because the connection pool has been closed

Question

I was reading through StackOverflow about this question and I still haven't found a solution. I notice that sometimes, my app throws this error:

   java.lang.IllegalStateException: Cannot perform this operation because the connection pool has been closed.         at android.database.sqlite.SQLiteConnectionPool.throwIfClosedLocked(SQLiteConnectionPool.java:962)         at android.database.sqlite.SQLiteConnectionPool.waitForConnection(SQLiteConnectionPool.java:599)         at android.database.sqlite.SQLiteConnectionPool.acquireConnection(SQLiteConnectionPool.java:348)         at android.database.sqlite.SQLiteSession.acquireConnection(SQLiteSession.java:894)         ... 

I have a file called DatabaseHelper.java using this approach to get an instance of it:

public static DatabaseHelper getInstance(Context context) {     if (mInstance == null) {         mInstance = new DatabaseHelper(context.getApplicationContext());     }     return mInstance; } 

Then I have methods like this one (that it crashed in the line cursor.moveToFirst() with that error). It almost never crashes, but sometimes it does.

public Profile getProfile(long id) {     SQLiteDatabase db = this.getReadableDatabase();      String selectQuery = "SELECT * FROM " + TABLE_PROFILES + " WHERE " + KEY_PROFILES_ID + " = " + id;     Cursor cursor = db.rawQuery(selectQuery, null);      // looping through all rows and adding to list     Profile profile = new Profile();     if (cursor.moveToFirst()) {         doWhatEver();     }     cursor.close();     db.close();      return profile; } 

So that's it, in all the methods I use:

SQLiteDatabase db = this.getReadableDatabase(); (or Writable) 

And then I close the cursor and the db. In this case, the error got throw in the line:

cursor.moveToFirst(); 

I do not see why the error says the db is closed if I am calling this.getReadableDatabase() before. Please support! Thank you :)

Answer 1

Remove

db.close(); 

If you try another operation after closing the database, it will give you that exception.

The documentation says:

Releases a reference to the object, closing the object...

Also, check out Android SQLite closed exception about a comment from an Android Framework engineer which states that it is not necessary to close the database connection, however this is only when it is managed in a ContentProvider.