Java Glossary

My concern is to maintain this java glossary, as simple as possible. For this reason I will define a very few terms here (no more than 70).

Class :

See :

• Base Class / Super Class / Parent Class
• Derived Class / Sub Class / Extended Class / Child Class
• Java Class
• Top Level Class
• Nested Class
• Inner Class

Base Class / Super Class / Parent Class :

Derived Class / Sub Class / Extended Class / Child Class :

IS-A relationship :

• The relationship shared by base classes and derived classes.

extends :

• The keyword used by a class to inherit another class and by an interface to inherit another interface.

implements :

• The keyword used by a class to implement an interface.

Java Class :

• In JAVA, a class represents a description (i.e template) of an object. A class is defined in a .java source file and compiled into a .class file. The purpose of a Java Class is to define the state and the behavior that objects of its type support.

Java Source Code :

• The aim of a java source code file is to define classes and interfaces.
• Basically, it is a text file with the extension .java.

Constructor :

• A constructor is a special method within a class that gets invoked when an object is instantiated. The purpose of a constructor is to initialize the fields of the object.
• A constructor must match the name of the class and cannot declare a return value.

Fully qualified name of a class :

• Consider the String class from Java API. It is defined in the package java.util. The fully qualified name of the String class is : java.util.String.

Identifier :

• A name for a java component. In Java Programming Language, there are rules for identifiers. Beyond the rules, developers created conventions for identifiers. Make use of them!
• Keep in mind that in Java, identifiers are case-sensitive.

Inheritance :

 

Keywords :

 

Object :

• The objects exist at runtime. They are created by the JVM when the new keyword is encountered. The object will have its own state and behavior. Sometimes, developers refers to an object by using the term: instance of a class.

Top-level class :

• A top-level class is a class which isn’t defined within any other class.

Nested class :

• A nested class is a class which is defined within another class.
• It is also called inner class.

Inner class :

• see nested class.