AP Java Unit 2: Class Structure and Design

assignment

using assignment operator = to initialize or change value stored in a variable

data type

format of data that can be stored in a variable (int, double, etc.)

declaration

giving a name and data type to a variable

intialization

giving a starting value to a variable using assignment operator =

literal

source code representation of a value, like number or text

primitive type

basic data type that Java predefines

reference type

data type that contains a pointer to the memory location of an object

variable

container that stores a value in memory

ArithmeticException

error caused by dividing by zero

compound assignment operator

shortcut syntax to perform an operation and store the result (+=, /=, etc.)

compound expression

combination of expressions

expression

combination of data and operators that evaluate to single value

operand

data that is operated on

truncate

to cut off data from end

access modifier

keyword used to set visibility of classes, variables, constructors, and methods

encapsulation

object-oriented programming concept where the instance variables of a class are hidden from other classes

instance variable

variable defined in a class that represents an attribute of an object

actual parameter

value given to an attribute when initializing an object

call by value

copying the value of the actual parameter to the constructor's formal parameter

default value

predefined value used by a program when the user doesn't provide a value

formal parameter

values to be passed to a constructor or method

local variable

variable declared and accessible within a specific block of code

no-argument constructor

constructor with no parameters

overloading

defining two or more constructors/ methods with the same name but different signatures

parameterized constructor

constructor with a specific number of arguments to be passed to assign values to an object's instance variables

NullPointerException

error when a reference doesn't point to an object

null

indicated that the variable doesn't refer to any object

application program interface (API)

library of prewritten classes

library

collection of methods or reusable components of code

DRY principle

stands for "Don't Repeat Yourself" and aims to reduce repetition in code

refactor

improve readability, reusability, or structure of program code without altering functionality

return keyword

exits method and provides the value to where the method is called

accessor method

gives value stored in an instance variable

return by value

copy of value given to where method is called

return type

type of value to be given from method

Boolean expression

logical statement that gives true or false value

Sentinel Value

special value used to notify program to stop accepting input

mutator method

changes value stored in instance variable

relational operator

operator used to compare values or expressions

escape sequence

starts with a \ to indicate how to display a String

override

define a method in a subclass with the same method signature as a method inherited from a superclass

this keyword

used to refer to the current object in a method or constructor

scope

where a variable can be used