Primitive Data Types and Classes

Java has many data types built into it, and you (as a programmer) can define as many more as you need. Other than the primitive data types, all data types are classes. In other words, data is either primitive data or object data. The only type of data a programmer can define is an object data type (a class). Every object in Java is an instance of a class. The class definition has to exist first before an object can be constructed.