SQLiteDatabase usage pattern [duplicate]

Question

I currently use the following pattern when accessing my SQLite database (possibly from different threads):

try(SQLiteDatabase db = new MySqliteOpenHelper(context).getWritableDatabase()) {
    ...
}

Until now I thought that it was clean and thread-safe, but I got some crashes due to "Database is locked".

Why is this pattern wrong and how should I change it?

what's MySqliteOpenHelper ? Which part do you think is thread safe? — Blackbelt
– Blackbelt, Commented Jan 27, 2017 at 16:54

Ryan · Accepted Answer · 2017-01-27 17:00:25Z

1

MySqliteOpenHelper is not a singleton. To create a singleton in that class do the following in MySqliteOpenHelper.

1 Add a static instance variable of type MySqliteOpenHelper

2 Add a method called getInstance(Context) (body as shown below)

public synchronized static getInstance(Context context){
    if(instance == null){
        instance = new MySqliteOpenHelper(context);
    }
    return instance;
}

This is thread safe as you will always be using one object.

edited Jan 27, 2017 at 17:00

answered Jan 27, 2017 at 16:59

Ryan

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10 Comments

sdabet Over a year ago

But I've read that SQLiteOpenHelper is supposed to handle thread safety, isn't it?

Ryan Over a year ago

I've never read anything similar, do you have a source?

sdabet Over a year ago

stackoverflow.com/a/6675272/569558 : "You shoud use locking-related SQLiteHelper methods to provide thread safety."

Ryan Over a year ago

That's saying SQLiteDatabase is thread safe not SQLiteOpenHelper

sdabet Over a year ago

You're right, but then why do I need to handle thread-safety myself if SQLiteDatabase handles it?

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