How to enable offline reading in my application?

Question

Context
I have a news activity which contains a ListView . Each item in the list contains some text and one image. Now every time the user opens the activity, the application makes a request to the server for getting data. Unfortunately if the user doesn't have an active internet connection, I simply put a Toast saying "Please check your internet connection"

Requirements
I would like to show news article from the last session if the user doesn't have an active internet connection. I define session as the time when user launches the activity and exits it by pressing back button.

Libraries used
I am using Retrofit Library for making Http Requests and Picasso for loading images.

What I have tried so far
While exploring Retrofit, I found out that retrofit by default caches the response for some time. So without any internet connection also I am able to get the data. In Picasso also, I found that we can save the image to any location on the device.

How to go for its Implementation ?
Since it will be a big change in my application, I wanted to know what is the best way to enable offline reading using the above two libraries? How do other applications manage to do so? Also if I can get some references or some blogs regarding this implementation, then it would be great.

Simply setup BroadcastReciever that listens for network change and if no internet available you should show data persisted on disk. — Nishant Srivastava, Dec 21 '15 at 08:51

score 1 · Answer 1 · edited May 23 '17 at 11:52

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Use the internal storage of the application.

Parse the image to a byteArray and the text to a single String so you can easily convert this also to a byteArray.

Name the files so you can easily retrieve them and link them back together.

edited May 23 '17 at 11:52

Community

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answered Dec 21 '15 at 10:23

TheTool

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score 0 · Answer 2 · answered Dec 21 '15 at 08:45

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You can storage the last updated data on local, with SharedPreferences or json file. Instead of show toast, you can load the last updated data from local.

answered Dec 21 '15 at 08:45

Javi Chaqués

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SharedPreference is not the best choice because it's more for preferences than datas. – Cocorico Dec 21 '15 at 08:56
You can write a .json file and load it when the user doesn't have an active internet connection. – Javi Chaqués Dec 21 '15 at 09:29
Yes, you can write .json files in it, but it's a bad design. You have to read and parse all the json files to make orederby or other things. So, I recommand to start now with DB. I think he will later make other operations with items like find owner, order them, modify them and other stuff, so start now with DB is a good choice or you're assuming you will not do complex operation on items. – Cocorico Dec 21 '15 at 09:48

score 0 · Answer 3 · answered Dec 21 '15 at 08:51

Picasso is a good choice for images, it saves images locally and reuse it automatically later.

For your items, I suggest to use a small local DataBase : in Android, we use SQLiteDataBase. here is a small tutorial : http://www.androidhive.info/2011/11/android-sqlite-database-tutorial/

So, I suggest you this pattern

user opens activity
system retrieves data from database
in parallel, system starts to download the new items.
When new items have been downloaded, you should notice user like 9gag or Facebook apps do.

How to enable offline reading in my application?

3 Answers3