Android Different Types of Testing

I know there are some unit testing & integration testing for Android apps

What are details we will get by Testing ?

Could you please anybody explain Testing in Android as simple as possible.Some sample code snippet may be really helpful.

How to ensure that my code will not ends with UI freeze. ? Is there any testing method/procedure/tool for that ?

How to use traceview & Systrace ?

I have googled it a lot.But serach hits are few for Testing compared to Android programming .

I need some simple explanation thats why i am here .Lot of thanks in advance.I wish maximum number of answers. . . . .