Android Software Design Question - regarding singleton pattern

[MarkoSan]

Dear Sirs and Madams!

In my app I have a class, which sole purpose is communicating and transferring data from/to mysql database via server side php scripts. That works ok, but now I have a demand: CDatabaseManager class (object) should be visible to all classes (objects) in application and there should be only one instance (object) of this class. How do I achieve this?

Sincerely,
Marko

[badtea]

You could make your database access class into a ContentProvider, although that might be overkill. ContentProviders are mainly for sharing information between multiple apps. If you only need the information within a single app, you don't need a ContentProvider...but I think you could if you wanted to.

You could use a factory to ensure that only one instance of your database class is returned. The factory would have a static instance of your database class. All your other classes would call the factory to get access to the database.

Here's a simple example of a factory.

public class CDatabaseManagerFactory {

private static CDatabaseManager mDatabaseManager = null;

public static CDatabaseManager getInstance() {
        if (mDatabaseManager == null) {
            mDatabaseManager = new CDatabaseManager();
        }
        return mDatabaseManager;
    }
}

Your other classes would make database calls by doing something like this:

CDatabaseManagerFactory.getInstance().doDatabaseCall()