It saves your battery by two ways:
1. The best screens doesn't need energy to paint black pixels
2. This live wallpaper actually does nothing. Nothing is nothing. Not "loading a black image". The back it's blank, so your CPU will be thinking in other things, increasing your phone performance and decreasing the battery drain.
This is an Open Source project, so you can browse the source code and do cool things with it. You can also distribute the binaries of this project without worries. You'll find the source code at http://code.google.com/p/black-npe-live-wallpaper
When installed, look for "Without ViewHolder", "With ViewHolder" and "With Cached ViewHolder" icons in your launcher. They are 3 ListViews, with different ArrayAdapter. What's the more efficient?
This app is released under GPLv3, so don't hesitate to look its code, edit it, distriute it and show it in your classrooms. You'll find the explanation and the source code at http://kcy.me/5l8j
The banana magic icon of this app had been downloaded from http://ztreasureisle.wikia.com/wiki/Emerald_Island and is released under Creative Commons (CC-BY-SA)
And the big picture at Android Market had been found at Wikipedia: http://upload.wikimedia.org/wikipedia/commons/8/89/Green_yellow_bananas_dsc07775.jpg
With this app you'll see how many bikes are available at Bicing's stations, have a list of your favourite stations and a map of the whole city.
If you're using this app, rate it!
- The data about the stations availability is provided by Citybikes (http://citybik.es)
- The data about the cycle lanes has been extracted from the PDF offered by Bicing (http://bicing.cat)