Java Final

Character class

class whose instances can hold a single character value. This class also defines methods that can manipulate or inspect single-character data.

String class

a built-in Java class used to work with string data.

StringBuilder class

an efficient built-in Java class for storing and manipulating changeable data composed of multiple characters

StringBuffer class

a thread safe class for storing and manipulating changeable data composed of multiple characters.

anonymous object

ab unnamed object

String variable

a named object of the String class.

immutable

describes objects that cannot be changed

lexicographical comparison

a comparison based on the integer Unicode values of characters.

concatenation

the process of joining a variable to a string to create a longer string

wrapper

a class or object that is “wrapped around” a simpler element

threads of execution

units of processing that are scheduled by an operating system and that can be used to create multiple paths of control during program execution.

buffer

a memory location that holds data temporarily—for example, when creating a StringBuilder object or during input and output operations

capacity

an attribute of an ArrayList whose value is the number of items it can hold without having to increase its size. Also, with a StringBuilder object, the actual length of the buffer, as opposed to that of the string contained in the buffer.

array

a named list of data items that all have the same type

element

one variable or object in an array

subscript/ index

an integer (contained within square brackets in Java) that indicates one of an array’s variables, or elements

out of bounds

describes a subscript that is not within the allowed range for an array

initialization list

a series of values provided for an array when it is declared

populating an array

the act of providing values for all of the elements in an array

enhanced for loop/ foreach loop/ flag

a language construct that cycles through an array without specifying the starting and ending points for the loop control variable

searching an array

the process of comparing a value to a list of values in an array, looking for a match.

parallel array

an array with the same number of elements as another, and for which the values in corresponding elements are related.

range match

the process of comparing a value to the endpoints of numerical ranges to find a category to which the value belongs.

passed by value

describes what happens when a variable is passed to a method and a copy is made in the receiving method

passed by reference

describes what happens when a reference (address) is passed to a method

Unified Modeling Language (UML)

a graphical language used by programmers and analysts to describe classes and object-oriented processes

class diagram

a visual tool that provides an overview of a class. It consists of a rectangle divided into three sections—the top section contains the name of the class, the middle section contains the names and data types of the attributes, and the bottom section contains the methods

base class/ superclass/ parent class

a class that is used as a basis for inheritance

derived class/ subclass/ child class

a class that inherits from a base class

containment

the relationship between classes when one class contains fields that are members of another class. See has-a relationship, composition, and aggregation

aggregation

a type of containment in which a class contains one or more members of another class that would continue to exist without the object that contains them

extends

a keyword used to achieve inheritance in Java

upcast

to change an object to an object of a class higher in its inheritance hierarchy

subtype polymorphism

the ability of one method name to work appropriately for different subclasses of a parent class

override annotation

a directive that notifies the compiler of the programmer’s intention to override a parent class method in a child class

super

a Java keyword that always refers to a class’s immediate superclass

protected access

describes an intermediate level of security between public and private; a class’s protected members can be used by a class and its descendants, but not by outside classes

fragile

describes classes that are prone to errors

virtual method calls

method calls in which the method used is determined when the program runs, because the type of the object used might not be known until the method executes

inlining

an automatic process that optimizes performance by replacing calls to methods with implementations

volatile storage

memory that requires power to retain information

random access memory (RAM)

temporary, volatile storage

nonvolatile storage

storage that does not require power to retain information

computer file

a collection of stored information in a computer system

permanent storage devices

hardware storage devices that retain data even when power is lost

text files

files that contain data that can be read in a text editor because the data has been encoded using a scheme such as ASCII orUnicode

data files

files that consist of related records that contain facts and figures, such as employee numbers, names, and salaries

program/ application files

files that store software instructions

binary files

files that contain data that have not been encoded as text; their contents are in binary format

root directory

the main directory of a storage device, outside any folders

folders / directories

elements in a storage organization hierarchy

path

the complete list of the disk drive plus the hierarchy of directories in which a file resides

path delimiter

the character used to separate path components

factory methods

methods that assist in object creation

absolute path

a complete file path that does not require any other information to locate a file on a system

relative path

a path that depends on other path information to be complete

static import feature

a feature in Java that allows you to use static constants without their class name

TOCTTOU bug

an acronym that describes an error that occurs when changes take place from Time Of Check To Time Of Use

character

any letter, number, or special symbol (such as a punctuation mark) that comprises data

field

a data variable declared in a class outside of any method; in reference to storage, a group of characters that has some meaning

record

a collection of fields that contain data about an entity

sequential access file

a data file that contains records that are accessed one after the other in the order in which they were stored

comma-separated values (CSV)

fields that are separated with a comma

open a file

the action that creates an object and associates a stream of bytes with it

close the file

to make a file no longer available to an application

stream

a pipeline or channel through which bytes flow into and out of an application

flushing

an operation to clear bytes that have been sent to a buffer for output but that have not yet been output to a hardware device

batch processing

processing that involves performing the same tasks with many records, one after the other

real-time

describes applications that require a record to be accessed immediately while a client is waiting

interactive program

a program in which the user makes direct requests

random/ direct/ instant access files

files in which records can be located in any order

file channel

an object that is an avenue for reading and writing a file

seekable

describes a file channel in which operations can start at any specified position

wrapped

to be encompassed in another type

key field

the field in a record that makes the record unique from all others