logcat

Filter adb logcat, tag logs with Log.d, and show one tag exclusively with -s.

Android logcat: http://developer.android.com/tools/help/logcat.html.

Pipe logcat through grep:

adb logcat | grep <>

Write a debug line from an activity:

Log.d("<Activity>","what you want to log");

Then read that tag only:

adb logcat -s <Activity>

-s shows that tag exclusively.