just figuring this out now, but, the whole chain in eclipse is byzantine.
...
went back to the android webpage, got the android SDK installer downloaded. ran it. it says i don't have a java JDK (why doesn't the android SDK download and install it while it's downloading the android SDK?)
went to the sun--sorry, oracle--webpages, got the java JDK installer downloaded. ran it. it installed with the only hitch being that i had to kill eclipse because it was using some files the java JDK installer wanted to munge.
ran the android SDK installer again. it says i don't have a JDK. nice. i just installed one. probably redundantly, at that.
according to this
64 bit - Huh? JDK not found? (on Windows 7 64-bit) - Super User the android SDK installer is stupid and looks only for the 32-bit JDK. great. that page also suggests downloading the android SDK as a zip file. okay.
the page
Installing the SDK | Android Developers gives no hint at all as to what's an appropriate location to unzip the files, just says to use a "safe" one. bril.
nowhere in that page does it say whether the android SDK is 32- or 64-bit compatible, so choosing between Program Files and Program Files(x86) is a crapshoot. or should it go in one of the subdirs eclipse created in my home folder. that doesn't seem right; the ADT installer created a .android folder, but if ADT expects to be installed after the android SDK that folder can't have existed before. unless the android SDK installer that didn't work would have created if it worked. but again since the .zip installation page is mute about appropriate locations, it's impossible to tell.
long story short: the android ADT installer should have been up-front about its dependencies, and the android SDK installer should have mentioned it only looks for 32-bit java JDKs, and the android SDK installation webpage should be more informative and less verbose. i'm learning way too much about the hierarchy of android dev tools, here, and wondering how anyone dumb enough to build and release a fart-noise app ever got this working.