How to take my programming skills to another level?

Question

Hello,
I am an on/off programming enthusiast for about 2 years. I have programmed in Pascal, C, C++, VB.net, C# and finally Java. I really do not spend all that much time learning these languages as it is in programming the syntax is easy to learn. Moving from one language to the next has prevented me from exploring the class libraries that each offers so I have since languished in mundane tasks.
I have decided to settle in Java because I want to start android programming and because I can also write desktop apps and because it is way faster to write programs in them than for say C. I really know a lot of the programming stuff like polymorphism and inheritance but I don't think I have ever used them. So here's my problem; I am not a programmer by education so I do not take classes in programming nor do I work as a programmer. I am not considering writing an OS anytime soon but I would like to create useful apps like for example using the free muPDF library to create a PDF reader or making a spectrum analyser etc etc. How can I do it and what should I do ?
Thanks.

Answer 1

I would probably start with http://www.tutorialspoint.com/java/ and once you have some comfort in these lessons move on to http://www.learnjavaonline.org/ for some interactive lessons, or can use them in tandem. For a lot of API programing I truly enjoy http://www.codecademy.com/.

Answer 2

In addition to the above answer, I would also take the time to pick up an algorithms book or even a design patterns book. You'd be surprised at how much better your code will be if you have this background!

Answer 3

You need to keep yourself updated on different programming language in order to be on track on what you do. Programming is a never ending learning where everyday, there's something new to learn.