Taming them initially is not so easy. It only works with very young birds, just out of the nest. The brownish bird in the photo below is a juvenile normal gray Java. It you don't get them at that age, taming is impossible - unless you hand feed them from the nest (which I'm sure is another hassle).
I tamed the original ones using the method described in the old TFH book Java Temple Birds" (1960), which involves wing-clipping and then working with them, away from other birds in a small room, like a parakeet. They definitely fight it longer than parakeets. But eventually they give up and sit on your finger. I did this initially with 3 birds all in separate cages and all tamed separately (but the cages were next to each other, except in the initial training sessions, which took place in a small room). Once they were tame, I rewarded them by letting them perch on my arm together. So eventually, they wanted to come out as soon as I'd walk into the room. Eventually, their wing feathers grew back and by that time, they were totally tame and would fly to me like a little flock.
As I have a real problem with the concept of wing-clipping any bird (but especially finches), I subsequently tried introducing a new fully-flighted baby to my flock, to see if he would become tame because he wanted to be with the other birds - and it works! But again, it must be a young baby and only one at a time. If young enough, they tame quite quickly this way because they want to be with the other bird. Now, my 3 current "second-generation" Javas were all tamed this way, one by one, with no wing-clipping. But I've also had 2 instances where taming them has been unsuccessful - I think because the birds were either a little too old or I didn't put enough time into it. And in those cases, you need to give that wild bird to someone else because he will have the effect of making your tame birds more afraid.
Once they are fully tame, they are fantastic pets with lots of personality. They get almost fearless and they do get attached to you. My flock will fly over to me when I'm watching TV and just park themselves on my shoulders for half an hour before they fly somewhere else. They have a very predictable pattern and where they like to fly in the two rooms they have access to. And mine know how to go back to their cage when it's time. When I had my original flock in my old house with the screened porch, I would leave them out there for hours in the summer and, when it was time to come in, I could literally hold my arm out and call them and all three would land on my arm and come back into the house!
The photo (in my original post) where they appear to be outside was taken on my screened porch, where I let them fly in the summer. The photos below were in my home office, where they don't fly to, too often.
I wrote an article on how to tame them and I submitted it to the Finch Information Center but I don't know if they put it out there yet. If you e-mail me, I can send you a copy. But I absolutely don't recommend trying to tame Javas unless you are really committed and you have a peaceful house without alot of noise, small children or cats. The initial taming process takes a few weeks, during which you must work at it at least once a day (but better with 2 or 3 training sessions per day).
Java Sparrows are apparently very popular in Japan, where people have them as tame pets like we have parakeets. I think they tame them by hand-feeding them for the last week or so before they fledge. Go here (it's in japanese)
http://www.annie.ne.jp/~linda/ and explore - the red text seems to be hypertext - eventually you will find photos.
