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Study guide: Object-oriented language basics, Part 1

Brush up on Java terms, learn tips and cautions, and review homework assignments

By Jeff Friesen, JavaWorld.com, 04/06/01

Glossary of terms

behaviors

Activities that some entity (such as a car) is capable of performing. Also known as functions.

class

Source code blueprint for objects.

class instance

A synonym for object.

creation operator

The new keyword, which allocates an object's memory and initializes that memory to default values. Note: The Java Language Specification does not refer to new as an operator. However, many developers do refer to new in that capacity.

doclets

Small documentation programs that the Javadoc tool processes.

dot operator

The period character (.). Note: The Java Language Specification does not refer to the period character as a dot operator. Instead, the JLS refers to it as a separator because it separates a class name or a reference variable name from a field variable or a method.

encapsulation

A primary object-oriented programming principle. The integration of state variables and behaviors into objects.

functions

Named bodies of code.

information hiding

A concept that facilitates program maintenance by hiding state variables and behaviors that don't need to be externally accessed.

object

A class instance.

pointers

Variables that contain the addresses of other variables.

references

Abstract object identifiers.

starting class

The first program class that the JVM loads.

state

The data values of some entity.

Tips and cautions

These tips and cautions will help you write better programs and save you from agonizing over why the compiler produces error messages.

Tips

• You might find it helpful to visualize objects as circles that are referenced by reference type variables.

Cautions

• You cannot use a reserved word to name a class. If you do, the compiler reports an error.
• The compiler reports an error if you declare two or more classes (in the same source file) with keyword public.
• Attempts to create objects from abstract classes result in compiler errors.

Homework

Read what The Java Language Specification says about classes and objects.

Experiment with the javadoc tool and explore the SDK documentation to find out what it has to say about javadoc.