I first thought you meant the computer desktop background LOL
Taking specific courses for Android development seems like a waste; the difference between Android and Java are very minor and Java will look better on your resume than Android.
Sorry I disgree with the above statement somewhat. Mobile Development is on the increase and has been the past couple years, since the iPhone really kicked mobile development in high gear. While it is true that you are much more likely to get a job as a Java developer, you can't disgard the fact that Android development jobs are increasing.
I did a quick search for Android Mobile as search keywords on Monster.com, Dice.com, and Careerbuilder.com and got the following results as of today.
- Monster.com - 33 jobs
- Dice.com - 534 jobs
- Careerbuilder.com - 251 jobs
Java is definitely needed for Android development, if you don't plan to develop using something like AppInventor or any of the other frameworks available for Android development that don't require developing directly with Java. Just don't discount the availability of employers looking for people with Android development skills.