well...nothing is purely oop or procedural. But some have more support for oop concepts and doing oop stuff. Java has many classes that supports oop porgramming methods which makes the programmer's life eay. So many say it is an oop language. You can write programs in procedural way in Java too if you want.
One of the main difference betwen oop and procedural programming is that in OOP, you can create OBJECTS and work with them easiliy which makes your life easier. in procedural programming, there are no so called Objects. So it is like you have to repeat most of the things again and again. Well...this is not a big explnation. You should know whatis an object to understand this.
this book called "head first java" answers your question with examples very nicely in their first pages. You should read it. At least first few pages to get a real answer.