Java Fundamentals

A comprehensive overview of fundamental computer science terms and Java programming concepts. External links are provided in case of special interest in a particular topic. With specific programming definitions/keywords, please note that this article explains the fundamentals of Java, and many of the external links point to Wikipedia, which will usually be generalizing on behalf of all languages.

Computer Science Terminology

General

Abstract class: A base class that passes general shared methods with no implementation down to other classes.

Argument: A data item specified in a method call, passed as a parameter. An argument can be a literal value, a variable, or an expression.

Assign: To throw away the old value of a variable and replace it with a new one.

Behavioral: Characterize the ways in which classes or objects interact and distribute responsibility.

Block: A sequence of statements, local class declarations and local variable declaration statements within braces.

Casting: Explicit conversion from one data type to another.

• Upcasting: Permits an object of a subclass type to be treated as an object of any superclass type.
• Downcasting: Permits an object of a superclass type to be treated as an object of any subclass type.

Class: The blueprint for an object to be instantiated from containing attributes, data structures, and methods. This is also a Java keyword, and cannot be used as the name for a variable.

Composition: Creates an object of another class to use. (A “has a” relationship.)

Creational: Involved with the process of creating objects.

Database: A structured set of data held in a computer, esp. one that is accessible in various ways.

Declare: A declaration states the type of a variable, along with its name. A variable can be declared only once. It is used by the compiler to help programmers avoid mistakes such as assigning string values to integer variables. Before reading or assigning a variable, that variable must have been declared.

Encapsulation: Keeps data hidden and allows for adaptability through organization / code reuse.

Enumerations: Identifiers that behave as constants in the language.

Equality: One way for primitives, four for objects a==b, a!=b will only be true if two references point to the same underlying object.

Equivalence: When !(a