I'm working on LinkedIn ingratiation in my Android app, and I've completed this using simple Webview which will ask for Email and password every time,
what i want to do is getting the Login credential from LinkedIn app (if already installed in device), as in Facebook. But i'm not able to find any tutorial about it. Plz help me out.
Thanks
You can not and should not. On Android all apps have a private area to store their data. Unless you have root you can't read another app's data (unless the info is saved to public storage which in this case it is not).
What you should be doing is getting your own authorization by asking the user directly for details and permission and using that. I believe LinkedIn uses OAuth2.0 so look into logging in using that.