应用变量的效率？

Question

I have a database from where i need to extract quite a lot of data. Now i get that data when required, ie I have made a class that handles database interactions and whenever an activity requires data it will call that class for the data. So at a time an Activity only has the bare minimum amount of data in memory (ie the data that it is using). But everytime i change an activity i have to perform database access to fetch data for the new activity.

Method 2

As opposed to this i have this other alternative, in which i make an application object and then perform database access in the beginning and then store all the data that i would require (in all the activities) in the application object. Whenever i need the data, i refer to the application object. The downside of this that i will be holding too much extra data that i am not using at a given instant.

Which of the above 2 approaches is better?

Thank you in advance.

Answer 1

It depends on your requirements and their priorities. If the time required for solution 2 is too long for you to accept then optimize (eg by using method 2, but in general I would advise against storing potentially all of your database in memory ... assuming the amount of memory will suffice).

Did you try solution 1. If the problem is only to read the data from database, it should not take too long to load the data for one activity. If complex calculations are involved you might be pressed to optimize. But don't optimize just in case!

Answer 2

我之所以喜欢第一种方法，是因为除非多个应用程序都可以访问数据库，否则调用数据库并不昂贵。