android - Logcat window clearing immediately on run -

when run android app, logcat window fills , clears. have system.out.println()'s aren't showing up, nothing showing , have no idea why.

edit: using android studio

i have had lot of issues logcat in android studio, here's few items:

1. in run configuration (just left of play button, select "edit configuration" drop-down, can configure couple of options related logcat, including whether or not android studio clear on startup
2. if debugger disconnects lose connection logcat. (some kinds of errors seem force disconnect debugger. i'm not entirely sure why.)
3. if never clear logcat, android studio attempt display entire logcat since last time restarted device/emulator. can take long time, , may display blank screen while it's processing.
4. by default, android studio try filter out messages unrelated app. in experience, never works right. think it's easier search tag you're looking for.
5. i haven't tried system.out.println() in android studio, typical android way print debug messages log.d. log located in android.util.log. android studio import automatically if type log , press alt+enter.

my guess problem isn't it's clearing logcat, it's not clearing logcat , android studio choking on large of log file. either select auto-clearing run configuration window or try walking away few minutes , see if logcat ever comes back