Why is Java not a pure OOP Language?

Java

Java is a OOP language and it is not a pure Object Based Programming Language.

Many languages are Object Oriented. There are seven qualities to be satisfied for a programming language to be pure Object Oriented. They are:

1. Encapsulation/Data Hiding
2. Inheritance
3. Polymorphism
4. Abstraction
5. All predefined types are objects
6. All operations are performed by sending messages to objects
7. All user defined types are objects.

Java is not because it supports Primitive datatype such as int, byte, long... etc, to be used, which are not objects.

Contrast with a pure OOP language like Smalltalk, where there are no primitive types, and boolean, int and methods are all objects.