Java vocabulary

import

A Java keyword used at the beginning of a source file that can specify classes or entire packages to be referred to later without including their package names in the reference.

public

A Java keyword used in a method or variable declaration. It signifies that the method or variable can be accessed by elements residing in other classes.

private

A Java keyword used in a method or variable declaration. It signifies that the method or variable can only be accessed by other elements of its class.

void

A Java keyword used in method declarations to specify that the method does not return any value.

if

A Java keyword used to conduct a conditional test and execute a block of statements if the test evaluates to true.

new

A Java keyword used to create an instance of a class.

int

A Java keyword used to define a variable of type integer.

return

A Java keyword used to finish the execution of a method. It can be followed by a value of the type required by the method definition.

Class

A class definition defines instance and class variables and methods, as well as specifying the interfaces the class implements and the immediate superclass of the class. A class name always starts with a capital letter.

field

A data member of a class. Also known as an instance variable. They are always declared private.

method

A function defined in a class.

Constructor

A piece of code that creates an object. In the Java programming language, constructors have the same name as their class and also start with a capital letter. Constructors are invoked using the new keyword. There can be more than one constructor to a class.

Compiler

A program to translate source code into code to be executed by a computer. The Java compiler translates source code written in the Java programming language into bytecode for the Java virtual machine.

primitive type

A variable data type in which the variable's value is of the appropriate size and format for its type: a number, a character, or a boolean value.

instance

An object of a particular class. In programs written in the Java programming language, an instance of a class is created using the new operator followed by the class name.

instance variable

Any item of data that is associated with a particular object. Each instance of a class has its own copy of the instance variables defined in the class. Also called a field.

Comments

Explanatory text that is ignored by the compiler. In programs written in the Java programming language, comments are delimited using // or /* ...*/

boolean

Refers to an expression or variable that can have only a true or false value.

Keyword

Java sets aside words as keywords - these words are reserved by the language itself and therefore are not available as names for variables or methods. They all start with a lower case letter.

parameter

Parameters are the variables that are listed as part of a method declaration. Each parameter must have a unique name and a defined data type.

Concatenation

The actual meaning is 'to link together'. Concatenating Strings means to join different Strings together to form a new String. Using an empty String, denoted by "", will convert a number to a String so it can be displayed. The symbol used to join Strings is the + sign.

Object

The principal building blocks of object-oriented programs. Each object is a programming unit consisting of data (instance variables) and functionality (instance methods).

double

a data type used to denote a number with a decimal place e.g 2.15