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Actually, i am fetching XML from the web, parsing it and display it on the screen. The problem which i am getting is that the activity tries to load the data from web each time the activity is called.(Actually, my mobile app requires frequent trips to the server) So i am in search of the below solution:

On Re-launch of an activity, the data from web should not be loaded again. 
creating a class that i can use to transparently make application faster by
selectively caching items in memory.  And thus, making users very happy and 
This class can even apply individual refresh times to each cached item.

So, i think i need to store the data in Cache or something like that.

Is there any way/technique to implement such thing ? so that it need not to load every-time on Re-launch of an activity.

Paresh Mayani
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3 Answers3

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You could try using a Service for loading the data in the background at given intervals.

Christian
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  • ya it can be done using Service, but on re-launch of an activity, it should not go to fetch data from the web (data should be loaded from the cache or something like it, i think by doing so, the data loading speed is increased so user need not to wait for more) – Paresh Mayani Nov 12 '10 at 06:36
  • As stated in the comment below the activity should ask the service for the data and the service would then return the data in the cache. If the cache is empty the service loads it first and the activity will have to wait. The next time the activity starts the activity gets the data directly since it is then cached by the service. – Christian Nov 12 '10 at 07:16
  • this is also the better idea but i needs to have large data to be fetched from the web and thanx for the support – Paresh Mayani Nov 13 '10 at 09:13
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Well what I would have done is to make a table , lets say call it "Table_Web_XML" , and appropriate fields in it to store specific web data .

When starting the Activity I would have first check if there is data in the database. If the table is empty (meaning the Activity is loading for the first time ) , I would load it from the web and display on the screen and save in database.

On the other hand if there is data in the table, then i would load it on the screen, and would start a service in background that would update my database table if there is any changes in it on the Web . What this would do is for system response point of view, the data will always be loaded fast, when the activity is repeatedly opened, and background service will ensure new and latest content on subsequent requests :) . Hope it helps.

Muhammad Shahab
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  • ya it can be do, but there are many xml files so for each xml, should i create table for each? – Paresh Mayani Nov 12 '10 at 07:03
  • If your purpose it to load your application fast , sure you can create more tables in a single database. The trade off here is to compromise on few kilobytes of disk space for each table. – Muhammad Shahab Nov 12 '10 at 08:00
  • thanx for the support, but how do i do it? if you have any example/code then pls suggest me or show me a way !! – Paresh Mayani Nov 12 '10 at 12:14
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Not sure what the performance would be with this suggestion, but the by far easiest if you just want to avoid fetching the XML files every time your activity re-launches, is to save them to Internal Storage. When your activity (re-)launches, you'll start by checking if the files exist locally before you fetch them from the web.

You would of course need come kind of logic to tell whether an XML file is "out of date" (you could have a simple database table with file names and last-fetched dates), and you would probably also like to have some kind of clean-up logic to delete files when you no longer need them so they don't fill up unnecessary space.

Julian
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