Java is a modern language with increasingly popularity. The designers knew what didn't work too well in previous languages and fixed it when designing Java. Java runs in virtual machines installed on different platforms making the language platform independent (as long as there is a JVM for the platform, which there generally is). The structure of the language is very well planned, it's hard to do something wrong (like dreaded memory leaks in c++ programs) and very easy to use special things like i.e. multiple threads.
The more I use the language the more I love it. The language is extremely consistent and encourages neat and maintainable programming code. There are many free compilers, the best (and free) compiler in my opinion is Eclipse.