java chapter 2
constant
describes values that cannot be changed during the execution of an application.
literal constant
a value that is taken literally at each use. See also unnamed constant.
numeric constant
a number whose value is taken literally at each use.
unnamed constant
a constant value that has no identifier associated with it. See also literal constant.
data type
describes the type of data that can be stored in a variable, how much memory the item occupies, and what types of operations can be performed on the data.
primitive type
a simple data type. Java’s primitive types are byte, short, int, long, float, double, char, and boolean.
reference types
data types that hold memory addresses where values are stored.
reference types
data types that hold memory addresses where values are stored.
variable declaration
a statement that reserves a named memory location.
strongly typed language
a language in which all variables must be declared before they can be used.
camel casing
a naming style in which an identifier begins with a lowercase letter and subsequent words within the identifier are capitalized. Contrast with Pascal casing.
assignment operator
the equal sign ( = ); any value to the right of the equal sign is assigned to the variable or constant on the left of the equal sign.
initialization
the act of making an assignment at the time of variable declaration.
assignment
the act of providing a value for a variable.
Associativity
describes the order in which operands are used with operators.
lvalue
an expression that can appear only on the left side of an assignment statement. Contrast with rvalue.
rvalue
an expression that can appear only on the right side of an assignment statement. Contrast with lvalue.
uninitialized variable
a variable that has been declared but that has not been assigned a value.
garbage value
the unknown value stored in an uninitialized variable.
named constant
a named memory location whose value cannot change during program execution.
symbolic constant
Definition:
a named constant.
final
the keyword that precedes named constants, that describes superclass methods that cannot be overridden in a subclass, and that describes classes in which all methods are final.
blank final
a final variable that has not yet been assigned a value.
magic number
a value that does not have immediate, intuitive meaning or a number that cannot be explained without additional knowledge. Unnamed constants are magic numbers.
scope
the part of a program in which a variable exists and can be accessed using its unqualified name.
block of code
the code between a pair of curly braces.
concatenated
describes values that are added onto the end of another value.
integer
a whole number without decimal places.
int
a data type used to declare variables and constants that store integers in the range of -2,147,483,648 to 2,147,483,647.
byte
the data type that holds very small integers, from -128 to 127.
short
the data type that holds small integers, from -32,768 to 32,767.
long
a data type that holds very large integers from -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807.
lossy conversion
a data type conversion in which some data is lost.
lossless conversion
a data type conversion in which no data is lost.
boolean
a data type that can hold only one of two values—true or false.
relational operator
an operator that compares two items; an expression that contains a relational operator has a Boolean value.
comparison operator
a relational operator.
floating-point
describes a number that contains decimal positions.
float
a data type that can hold a floating-point value of up to six or seven significant digits of accuracy. Contrast with double.
double
a data type that can hold a floatingpoint value of up to 14 or 15 significant digits of accuracy. Contrast with float.
significant digits
refers to the mathematical accuracy of a value.
scientific notation
a display format that more conveniently expresses large or small numeric values; a multidigit number is converted to a single-digit number (possibly with decimal places) and multiplied by 10 to a power.
double-precision floating-point number
a type of value that is stored in a double.
single-precision floating-point number
a type of value that is stored in a float.
char
a data type that holds any single character.
escape sequence
a sequence that begins with a backslash followed by a character; the pair frequently represents a nonprinting character.
text block
a multi-line string literal that avoids the need for an escape sequence to display output on multiple lines.
standard input device
usually the keyboard.
token
a unit of data; the Scanner class separates input into tokens.
prompt
a message that describes and requests user input.
keyboard buffer
a small area of memory where keystrokes are stored before they are retrieved into a program. Also called the type-ahead buffer.
type-ahead buffer
a small area of memory where keystrokes are stored before they are retrieved into a program. Also called the keyboard buffer.
input dialog box
a GUI object that asks a question and provides a text field in which the user can enter a response.
type-wrapper classes
classes that contain methods that can process primitive type values.
confirm dialog box
a window that can be created using the showConfirmDia1og() method in the JOptionPane class and that displays the options Yes, No, and Cancel.
standard arithmetic operators
operators that are used to perform common calculations.
operand
a value used on either side of an operator.
binary operators
operators that require two operands.
Floating-point division
the operation in which two values are divided and either or both are floating-point values.
Integer division
the operation in which one integer value is divided by another; the result contains no fractional part.
remainder operator
the percent sign (%); when it is used with two integers, the result is an integer with the value of the remainder after division takes place. Also called the modulus operator.
modulus operator
the percent sign (%); when it is used with two integers, the result is an integer with the value of the remainder after division takes place. Also called the remainder operator, or mod.
Operator precedence
the rules for the order in which parts of a mathematical expression are evaluated.
type conversion
the process of converting one data type to another.
unifying type
a single data type to which all operands in an expression are converted.
implicit conversion
the automatic transformation of one data type to another. Also called promotion.
promotion
the automatic transformation of one data type to another. Also called implicit conversion.
Type casting
an action that forces a value of one data type to be used as a value of another type.
cast operator
an operator that performs an explicit type conversion; created by placing the desired result type in parentheses before the expression to be converted.
explicit conversion
the data type transformation caused by using a cast operator.
unary cast operator
a more complete name for the cast operator that performs explicit conversions.
unary operator
an operator that uses only one operand.