I am a beginner for Java programming. I started to self study by referring java documentation. But it is too complicated. But I followed language basics. After that I am in a trouble to select that , which java technologies to study. My dream is to be a java developer. Anyone can guide me?
After that I am in a trouble to select that , which java technologies to study
Presumably you have in fact managed to create some simple programs and now you have reached the point where you want to study some part of java without attempting to learn everything at once.
If you like pretty pictures you can learn swing although you probably shouldn't spend too much time on that since most new development won't use that. Despite that learning the basics of graphics can still be helpful. And it is possible that you will encounter this at some point.
Alternatively to that is you could learn how sockets work. Build a chat program (swing could help with that but not necessary.)