well as you all know (or most of you do) I naturally grow cladophora (algae) in the tank which is very similar to moss balls...there are huge clumps of the algae throughout the tank (I do prune it at times, but believe it or not, once it is pruned consistently over a period of weeks, it will literally grow the way I pattern or shape it)
as long as the plant has a stem, yes you can....
Take a top cutting, snip off a length of stem with several nodes or leaves; cut between the nodes with a good pair of scissors; take cuttings from the fastest growing or healthiest stem...next, strip away the leaves from one or two nodes at the base of the cutting to allow the plant to root more quickly; roots will form from the stripped node; make sure it is beneath substrate when planting...next, push the cutting into the substrate so that the lower leaves are just resting on the substrate surface; roots should grow from the base and the plant will establish itself rather quickly, although don't panic if the lower leaves die off
in regards to doing this with java moss, it is quite impossible...but the key to any type of moss (algae is similar, that is, cladophora) is the way in which it is pruned or shaped, as you shape it it will spread out all over your tank, and as long as you shape it like the way you want it, it will know its bounds.. if you do shape it on a regular basis (once a week), you will see, in time, it will remain in place...for instance, I purposely permitted the algae/cladophora (somewhat like java moss) to spread all over the rocks and wood, and it stayed right there on those surfaces...every so often I will have some grow on the gravel, but by compressing it down, it has remained very low and in place
so the key to java moss is pruning or shaping it
in regards to stemmed plants, you can replant as often as you like...if any yellowing does occur, it is best to cut off those leaves for the decay will pollute the water and cause the rest of the plant to struggle, attempting to repair the loss leaf with its starches and proteins rather than grow faster, greener and more height
let us know if you have any other comments