What are the prerequisites for learning Java?

In fact, you can directly start learning Java without any prior knowledge of programming language.

But, the syntax in Java is similar to the syntax of the C programming language, therefore, Knowing C language helps to get hold of Java quickly.

Having introduced to object-oriented principles before starting Java, also helps in the understanding of the language so, having an idea on object-oriented languages such as C++ also helps.

In short, if you know C or C++ it will be a little bit easier to cope with Java technology.