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I read this question and wondered if the same would apply to my situation.

I want to write accelerometer values (x, y and z) from an Android phone to a database and retrieve it with another app on a tablet to display a graph of the values changing over time. This does not have to happen in real time.

So basically my questions are:

1) can two different applications on two different Android devices use the same SQLite database?

and

2) how do I specify an IP so that the one app on the phone writes to a specified database and the other app on the tablet reads from that same specified database?

I can already read the Accelerometer values and I know how to create a graph, but I'm having trouble with the database component of my project since everything I come across seems to be storing the values on the device's SD card or in a database that is only accessible to the device itself and no other applications or devices.

I've read about specifying a static IP by first obtaining a ContentResolver: 

ContentResolver cr = getContentResolver();

then adapting the settings: 

Settings.System.putString(cr, Settings.System.WIFI_USE_STATIC_IP, "1"); 
Settings.System.putString(cr, Settings.System.WIFI_STATIC_IP, "6.6.6.6");

and then enabling the permissions: WRITE_SETTINGS and WRITE_SECURE_SETTINGS.

but I'm not sure where exactly to write this or how to use it correctly.

Please direct me to where I can find some more information regarding setting up SQLite databases and how it can be used by two different applications on two different Android devices?

Thank you in advance.

P.S. I'll update this question with some of my code soon.

Community
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marienke
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  • Don't mess with the network settings when you can avoid it, your users will hate you for that -- either 1) display the IP address when your app starts on the tablet and ask for it on the phone app, or 2) use something entirely automagic like zero-conf networking via [JmDNS](http://jmdns.sourceforge.net/) (more work) – Philipp Reichart Sep 21 '11 at 12:57

3 Answers3

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can two different applications on two different Android devices use the same SQLite database?

No more than two Web servers running on two different continents can use the same MySQL database. Only processes running on a device with filesystem access to a file can read and write to that file.

how do I specify an IP so that the one app on the phone writes to a specified database and the other app on the tablet reads from that same specified database?

You don't. Android is not a server platform.

At best, you might be able to pull this off if both devices are on the same WiFi LAN, and you write a Web service that exposes a database from one device. This, of course, exposes you to the same security issues that you would have with a Web server, without the benefit of firewalls and the like.

I want to write accelerometer values (x, y and z) from an Android phone to a database and retrieve it with another app on a tablet to display a graph of the values changing over time. This does not have to happen in real time.

Hence, you do not need two devices to access the same database. You need them to work with the same data.

So, you could have the phone send the data to some server via a Web service, and have the tablet retrieve the data from that server via the Web service.

Or, have the phone send data to the tablet via Bluetooth.

Or, if you feel the security is adequate, have the tablet expose a Web service via WiFi that the phone uses (though this really scares me, particularly if the tablet might join some other network, such as by being moved).

In neither case does the phone nor the tablet necessarily even have a database, let alone try to directly share it.

CommonsWare
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  • Agree with this and was preparing similar answer. As for tablet exposing web service, it's worth taking a look at [nanohttpd][1], there's an example how to subclass and customize it. – Pēteris Caune Sep 21 '11 at 13:02
  • Ok thank you so much. I spoke to a guy working with me and he suggested something similar. He said that I should write data values from the phone to an xml file and then send the xml file to the tablet via email/bluetooth/ftp. The tablet can then simply use the file to create the resulting graph. This will not require a database and any issues with two devices sharing one database's info. Thank you for your replies. – marienke Sep 22 '11 at 10:58
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Although not SQLite, I believe this can be achieved using PouchDB, where you would host one shared remote database which would then sync to two seperate databases for each application.

https://pouchdb.com/

lky
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A SQlite database is private to the application which creates it. If you want to share data with other applications you can use a Content Provider.

Vijay
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