Android Nullpointerexception And Getdatabaselocked

Im trying to store a particular columns data in a method and call that method in another classes String [] where a spinner will access that array to display the columns rows for th

Solution 1:

The database doesn't get locked. The "locked" thinkg is just a NPE in a method called getDatabaseLocked() and it's caused by a nullContext passed to SQLiteOpenHelper in constructor that manifests itself with getWritableDatabase() or getReadableDatabase().

To fix the NPE in getDatabaseLocked(), make sure ourContext in open() is not null. As of now, you've never initialized ourContext and it's always null. Uncomment the //ourContext = c; in constructor and move it above the establishDb(), remove the other no-argument constructor and pass in a Context for example as suggested by Merlevede.

The NPE stacktrace in your question is when you call getCpNames() with open() commented out and are trying to call a method on a nullourDatabase object reference. Uncomment the open() there once it's fixed. The stacktrace also says you're trying to call getCpNames() in object initialization phase e.g. when initializing a member variable. That might be too early, for example an activity cannot be used as a Context until onCreate().

Some other things in your code you'd hit next:

• in onCreate(): + KEY_COST + " TEXTNOT NULL) - add space between TEXT and NOT

• in getData(): you're closing the cursor and database in the loop where you're accessing the cursor. Do it after the loop. The code shouldn't compile as you're not returning anything from a non-void function in case moveToFirst() returns false.

Solution 2:

Try updating your getInstance() code with this:

publicstaticCarParkDbgetInstance(Context c) // <-- added context as parameter
{
    synchronized(CarParkDb.class)
    {
        if (instance == null)
        {
            instance = newCarParkDb(c); // <-- used context in constructor
        }   
        return instance;
    }
}

The problem seems to be that you're using a constructor (for CarParkDb) that does nothing. You have another constructor that takes a Context as parameter and initializes some of the objects that you're using later.