I want to add a "Check for update" button in apps so that when someone clicks it, it will display a toast message / progress dialog for checking the app's version.
If new version is found the apps will auto download it to the phone and let user to manually install the updated apps.
Or any others method will do as long as it can check for latest version and notify the user to update.
Update: Now you can do this inside your app using https://developer.android.com/guide/playcore/in-app-updates
To save time writing for check new version update for android app, I written it as library and open source at https://github.com/winsontan520/Android-WVersionManager