CSCI 1301 Final Exam

computer systems

consist of hardware and software

program

a set of instructions for the computer to carry out

software

all the different kinds of programs used to give instructions to the computer

CPU (processor)

the device inside your computer that follows a program's instructions

memory

holds data for the computer to process, and holds the result of the computer's intermediate calculations

main memory (RAM)

volatile memory that holds the current program and much of the data that the program is manipulating; 100,000x faster than auxiliary memory;

auxiliary memory (secondary memory)

non-volatile memory that continues to exist when the computer's power is off.

byte

the smallest addressable unit of memory; consists of 8 bits

memory location

the address of adjacent bytes

operating system

a supervisory program that oversees the entire operation of the computer

high-level languages

must be translated into a language that the computer hardware can understand; typically easy to understand and write; (ex: Java)

machine language

the language that the computer can directly understand

assembly language

a symbolic form of machine language that is easier for people to read

low-level languages

only needs minor translation before it can be run on the computer

compiler

a program that translates a high-level language to a low-level language;

Java compiler

translates the Java language (high-level) into Java bytecode (low-level)

Java bytecode

a 'machine language' for a hypothetical virtual computer known as the Java Virtual Machine

Java Virtual Machine (JVM)

an interpreter that is responsible for translating Java bytecode into machine language and running the code

class loader

connects bytecode of various classes

applets

little applications meant to be sent to another location on the Internet and run there

statements

instructions within a method that define a task and make up the body of the method

variables

used in a program to store data such as numbers and letters; assigned a memory location

data type

specifies a set of possible values and the operations defined for those values

syntax

the grammatical rules for writing computer languages

value

the number, letter, or other data item inside a variable

variable declaration

includes a type name, & a variable name, and ends with a semicolon;

primitive type

variables of this type are more simple than objects, and hold data of several specified types

byte (type)

Primitive type:
Integer
-128 to 127
[1 byte]

short (type)

Primitive type:
Integer
-32,768 to 32,767
[2 bytes]

int (type)

Primitive type:
Integer
-2,147,483,648 to 2,147,483,647
[4 bytes]

long (type)

Primitive type:
Integer
[8 bytes]

float (type)

Primitive type:
Floating-point
[4 bytes]

double (type)

Primitive type:
Floating-point
[8 bytes]

char (type)

Primitive type:
Single character
[2 bytes]

boolean (type)

Primitive type:
true/false
[1 bit]

floating-point number

A number having a fractional part, such as 2.5

identifier

the name of a variable in Java; can only contain letters, digits, and underscore

assignment statement

A statement that assigns a particular value to a variable

assignment operator

=

constants (literals)

a variable that does not change in value

byte, short, int, long, float, double

type the order of primitive type assignment compatibility, left to right, with commas:

typecasting

changes the data type of a value from its normal type to some other type; truncates if going backwards in assignment compatibility

unary operator

an operator that only has one operand; + - ++ -- !

binary operator

an operator that has two operands; * / + -

highest precedence (operators)

unary operators (+ - ++ -- !)
[precedence?]

second highest precedence (operators)

binary arithmetic operators (* / %)
[precedence?]

lowest precedence (operators)

binary arithmetic operators (+ -)
[precedence?]

concatenation

an operation to combine strings; uses +

index

the position in a string or array

substring

a portion of a string

escape characters

special characters indicated with a backslash (\n, \t)

delimiters

specified characters (usually whitespace) that separate multiple inputs in a Scanner class

boolean expression

an expression that is evaluated as either true or false

conditional operator

?; used with the ternary operator : to assign a value; can replace an if-else statment

short-circuit evaluation

an evaluation made when Java only evaluates the beginning of an expression to determine if it is true or false. Use & and | instead of && and || to avoid

loop

a portion of a program that repeats a group of statements

iteration

one repetition of the loop body

while loop

a type of loop that repeats its body while the controlling expression is true (can preform 0 iterations)

do-while loop

a type of loop that repeats its body the controlling expression is true (body is always executed at least once)

infinite loop

a loop that iterates its body without ever ending

for loop

a loop that uses 3 expressions in its implementation to iterate the loop a specified number of times; used to count up or down

for each loop

a for loop that uses : to iterate over each value in an array

local variable

a variable that only has meaning inside the body it is declared in

scope

the portion of a program in which a variable has meaning

sentinel value

a value that a user can input to signal the end of a loop/input

object

an instance of a class

class

specifies the attributes/data (instance variables) that objects have

UML Class Diagram

a diagram designed to help outline a class

instance variables

the data items that belong to an object;

public

an access modifier that places no restrictions on how instance variables are used

methods

invoked or called to perform actions on an object; some return a value and some are void

void methods

methods that perform some action other than returning a value

return;

the line used in a non-void method to give back a value where it was called; ends a method's execution

this

the keyword used as a name for the receiving object in a method

block

a compound statement that declares a local variable

formal parameters

in a method, these parameters represent the actual argument in the method definition

actual parameters

in a method, these parameters represent the argument, or the value that is plugged into the method

byte, short, int, long, float, double

the order that automatic typecasting occurs in:

information hiding (abstraction)

designing a method so that it can be used without much understanding; separating the why from the how

precondition statement

a comment that states the conditions that must be true before a method is invoked

postcondition statement

a comment that describes all the effects produced by a method invocation

private

an access modifier that makes something inaccessible outside of the method it is declared in; instance variables should always be this

accessor method (getter)

a method that allows you to look at data contained in an instance variable

mutator method (setter)

a method that allows you to change the data stored in private instance variables

encapsulation

the process of hiding all the details of a class definition that are not necessary to understanding how objects of the class are used

implementation

the _____ of a class consists of all the private and public elements/methods of the class

+ (UML)

signifies public in a UML Diagram

- (UML)

signifies private in a UML Diagram

reference

the address of a memory location is a _____ to the object

reference type (class type)

a type whose variables hold references as opposed to actual values of objects

constructor

a special method that is called using the new operator; can initialize instance variables to your specifications

default constructor

a constructor with no defined parameters; must be included if another constructor is defined

static variable

belongs to a class as a whole and not an individual object; objects share this constant

final

this modifier prevents a static variable from being changed

local, instance, static

Java variable types:

static methods

methods that perform actions unrelated to an object; invoked using the class name; cannot reference an instance variable

wrapper class

these special classes convert each primitive type to a class type; Integer n = new Integer(42);

boxing

the automatic conversion/type casting from a primitive type to its corresponding class; Integer n = 42;

unboxing

the automatic conversion of an object of a wrapper class to a value of its associated primitive type; int i = n;

array

a collection of items of the same type