Here you'll find some of the implementations in android like...
The splash screen of android for 3 second
Splash screen also have sound
How to use web-fonts
How to add full-screen mode in android
Hide title bar and Status bar
Match username and password and then go to next activity
Pass data value to the next activity
Custom Toast
Show attempt if user enter the wrong password
If attempt match disable login button
Some condition for EditText
Change app icon and app name
Set screen orientation for activity
Add back button to activity
Fetch login data to the next activity
Flipper example (Change image as specifies seconds like animation)
Menu Activity (Go to any activity as specified in a listview or Open any activity with listview)
Back button with AlertDialog
Browser App
Go button
Forward button
Clear History
Refresh button
Load default web page
Search any website
Option menu
Wallpaper App
Open camera and set wallpaper
Sms application
Show and hide layouts
Include multiple layouts in single layouts