Objects

Java has very many data types built into it, and you (as a programmer) can create as many more as you want. However, all data in Java falls into one of two categories: primitive data and objects. There are only the eight primitive data types. Any data type you invent will be a type of object.

Much more will be said about objects in the future (since Java is a object oriented programming language.) The following will be all you need to know, for now:

• A primitive data value uses a small, fixed number of bytes.
• There are only eight primitive data types.
• A programmer can not create new primitive data types..


• An object is a big block of data. An object may use many bytes of memory.
• An object usually consists of many internal pieces.
• The data type of an object is called its class.
• Many classes are already defined in the Java Development Kit.
• A programmer can create new classes to meet the particular needs of a program.

A (crude) analogy is that a primitive data value is like a nut or a bolt, but an object is like a whole machine. If you want to learn more about objects right away, it would not hurt to jump ahead to the Chapter On Objects and read a few pages.