The article considers the implementation of Java enum types, starting from the API and ending with examples of the usage of inheritance in enums. The article is recommended reading for all java-programmers, regardless of experience.

The article information is constructed in such a way, that everybody will understand how to use them, even those who knows nothing about regular expressions.

In Java nested class - a class that is declared within another class declaration. Nested classes are divided into static and non-static . Strictly non-static nested classes have another name - inner classes.

The article presents the classification of collections in Java.