It's not uncommon for Javas to be either aggressive or 'wild'-fearful, pace the wire furthest from you and freak out bad when there are visitors. I'd say many are just a little more aloof than Indias, willing to come up, at least for familiar persons and maybe becoming more aloof with strangers around. Some can be really tame though. I don't raise any of my chicks very closely due to being allergic to bird dander. Mostly stand back and admire them as a result. That said, out of a clutch of 5 chicks, typically there will be one that wants nothing to do with me from almost day one, 2 "can tolerate me" very much lookee but no touchee, one fairly tame, willingly approaching me especially if I have food or treats, and one very tame, running up to and following me around like a puppy dog and refuse to get out of my way(but awful easy to teach tricks & charming...). I see all personalities any way they are raised- brooder, hen or peahen raised, however with the brooder raised groups, the 'very tame' ones are much more tame than those raised by hens. My friends who do the hatching for me now(again due to bird dander allergy) plays and handles the chicks a lot, most of the Java(and spalding) chicks started by them are tame to very very tame- walk up your arm as soon as you open the brooder.
Many feel they cannot be let loose at all, or too expensive to risk it. I've let some be raised free range, they stayed around but they did wander much farther than any of the Indias did.. had to put a stop to it when they started to spend parts of their days in neighbor's yards.... Had one breeder male somehow get out of his pen.. tried to herd him back in, normally I don't even try to, but he was already on far side of neighbor's yard and was never free range at all so I got worried enough to try herding him back towards my yard. Big mistake as he of course flew off in the opposite direction, way high up and far, far away.... He came back though, all I did this time was open a pen door, he walked right back in. Whew.....
Spaldings are a much better bet, if you have concerns about cold or you intend to let them loose and you're not on many acres... Keep in mind, due to the mix, some of the "Java problems" can show up in spaldings too.. some are just as shy/nervous, some can become aggressive. Not all though, none of my spaldings have ever tried to attack me even though some are so high percentage green blood they look very 'Java'. I've had and met very sweet/tame spaldings in both sexes.
One more con, is both Javas and mid-high range males can become fighters, not really tolerating other males well. They're always the bosses in mixed groups with Indias.
