Java

1D array

an array that stores data in one direction, where each position in the array is called an index. Stores elements of the same data type and is a static data structure

2D array

an array that stores data in two directions and is hence indexed with two numbers. Stores elements of the same data type and is a static data structure

Abstract data type

a mathematical model for data types, defined by its behaviour from the point of view of the user

Abstraction (N19 P1)

the process of taking away or removing characteristics from something in order to reduce it to a set of essential characteristics

Accessor (M25 P2)

methods that return the value of a private variable;
Allows accessing private variables from outside the class

Actions

methods

Aggregation

(N20 P2) when one class is contained inside another and used (classX includes fields of classY, but classY objects can exist in isolation of classX)

Argument

the value passed into a function or method when called

ArrayList

a dynamic data structure that stores data in one direction. Stores elements of the same data type

Binary search

a search algorithm that starts at the middle of a sorted set of data and removes half of the data by comparing the median value to the desired value

Boolean

used to represent data that can only take 2 values, using 1 bit of data

Bubble sort

a sort algorithm that moves through a set of data repeatedly, swapping elements that are in the wrong order

Char

16-bit Unicode character used to store any character

Class

a template, or blueprint, from which Java objects are created

Collection

a data structure designed to contain multiple elements of any data type and methods which make this data useful

Composition

a class holds a reference to another class as an instance variable. They can’t exist without each other

Constructor

sets up space in memory and constructs the state and value during object creation

Coupling

two classes that are dependent on each other are ‘coupled’. Coupling can be strong or weak. These are directional.

Default constructor (M24 P2) - instantiates an object of a class with null or default values without using any parameters

Dependency

a class depends on another class to use parts of that class

Doubly linked list*

a linked data structure that consists of a set of sequentially linked records called nodes. Each node contains two pointers (to the previous and the next node in the sequence) and one data field

Encapsulation (M18 P2)

allows the program to make instance variables of a class private so that the main program / other classes can’t accidentally access the data in the object

Fields

variables within a class

Final (M18 P2)

prevents variables from being modified

For loop

a control flow statement that repeatedly executes a block of code a predetermined number of times or while a condition remains true

Identifier (N19 P2)

the unique name of a program element

If and else statement

a control flow structure that executes a block of code if a condition is true, and an alternative block if it is false

Inheritance (N19 P2)
When a new class is derived from an existing class;
The new class inherits all variables, properties, methods, behaviours and data from the existing class;
The derived class is called a child / sub-class, the original class is called a parent / super class

Instance

a specific object constructed from a class

Instantiation

creating new objects within a class; another name for construction

Integer

a primary data type used to represent whole numbers in 32 bits

Library

collection of prewritten compiled code that is public for programmers

Linear search

a search algorithm that checks each element in order until the desired value is found or all elements checked

Linked list*

a linked data structure that consists of a set of sequentially linked records called nodes. Each node has a pointer (to the next node in the sequence) and one data field

Local variable

a variable that only exists while the code it belongs to is executing

Logic error

when the compiler runs the program but the program behaves unexpectedly

Long

64‑bit data type used to represent a wider range than integer

Method

a set of instructions that can be called for execution using the method name

Method overriding

replaces a method from the inherited class (M19 P2)

Method signature (M18 P2)

The signature/method name that defines the parameters and their types

Modern programming languages

programming languages that have been developed or significantly updates since the late 1990s to solve the limitations of older ‘legacy’ languages

Modulation

splitting a program into smaller modules that can be tackled individually

Mutator (M19 P2)

a method that sets the value of private variables in an object or class

Naming conventions

standardised rules for naming variables, functions, classes, and other entities to enhance code readability, maintainability, and consistency across projects

Object (M18 P2)

an abstract entity, its components are data and/or actions

Object reference (N19 P2, M19 P2)

a pointer to a memory location where the object is stored

OOP

a programming model focused on objects and their associated data and actions

Parameter

a variable named in the function or method definition

Parameter variable (M24 P2)
A value / variable passed when the function / method is called
It is found in the parameter list of the method signature

Polymorphism

the ability of objects to take on many forms, usually through inheritance

Primitive data type

data types that are fundamental in the programming language

Private

variables that are only accessible within the class

Protected modifier (M18 P2)

allows access to variables from within the package in which they are created

Public modifier (M18 P2)

allows access to the field/method from outside the class / allows unlimited access

Queue*

a linear abstract data structure following the First-In-First-Out (FIFO) principle

Real

represents decimal numbers using 32‑bit floats or 64‑bit doubles

Selection sort

repeatedly finds the smallest item and swaps it with the current index

Stack*

a linear data structure that follows the Last-In-First-Out (LIFO) principle

Static variable (M18 P2)

a variable that acts on the class as a whole and not on individual objects

String

represents a sequence of characters; not a primary data type

Syntax error

a mistake where programming language rules are not followed, preventing compilation

UML diagram

a graphical representation of classes, interfaces, and objects in an OO system are stored

Variable (N22 P1)

Unique identifiers that retrieve values from the memory addresses at which they are stored. They define areas in memory in which values are stored. Names given to computer memory locations which are used to store data values in a program

Void

indicates that a method/function returns nothing

While loop

repeatedly executes a block of code as long as a Boolean condition remains true