Question

Imagine a app showing the user statistics. I could have an Object like:

public class Statistic {
     private int id,value;
}

Where the value should persist between different app executions. Using an database for the persistent system the databaseAdapter could have a:

public void saveStatisticValue(int id,int newValue);
public int getStatisticValue(int id);

Using that calls to the DataBase Adapter in the getter/setter method of the object could impact in the app performance if called from the UI thread due to the database delay. For example if I want to show an Activity with all the Statistics, the database delay of the getter of each Statistic object could result in a ANR.

public class Statistic {

    ....

    public synchronized void setValue(int newValue) {
        dbAdapter.saveStatisticValue(this.getId(),newValue);
    }
    public synchronized int getValue() {
        return dbAdapter.getStatisticValue(this.getId());
    }

    ....

 }

Is there some kind of approach for reduce the database impact for this kind of models?

Thanks

Answer 1

As you already has observed, the geter/setter method to the Models should be asynchronized.

For example , the API to getter_statics could be :

Request getStatics(RequestCallback callback);

interface RequestCallback {
        void notify(int id ,int value);
}

The requestCallback will be called in the same thread as the getStatics has been called, usually it is the UI thread.

Two class are provided in Android facilitate you to implement this common pattern: Handler and SyncTask. Please read the document to get a thorough understanding.

You can also to check out this article.