Q:

Android Log Memory Usage

My question is simple.  In Android app, when we write  

Log.d("TAG","log message");

and run this app on device, where does this log goes?  We can see this log in logcat in Eclipse. 

A:

The log is saved on the device, sommewhere.  You can access it with 'adb logcat' commands in adb. 
Note that, when publishing the app, you should not log debug messages.  Errors only.