Java is often referred to as an object-oriented language, but it is not a purely object-oriented language. Although it was designed to be object-oriented from the ground up, there are several features of Java that make it fall short of being a purely object-oriented language.

Firstly, Java has primitive data types, such as int and boolean, which are not objects. These types do not have methods and cannot be used with the dot operator that is used to access an object's methods and properties. This means that Java code requires a mix of object-oriented and non-object-oriented programming techniques.

Secondly, Java has static methods and variables, which are associated with a class rather than an instance of the class. This means that they can be accessed without creating an object, and they do not belong to any particular instance of the class. This is a non-object-oriented feature of Java.

Finally, Java also has interfaces, which are like abstract classes that define a set of methods that a class must implement. However, interfaces cannot contain implementation code, which is a non-object-oriented feature.

In conclusion, Java is a mostly object-oriented language, but it is not purely object-oriented. Its use of primitive data types, static methods and variables, and interfaces means that it requires a mix of object-oriented and non-object-oriented programming techniques.