Chapter 2 Data Types
Predefined N_______F_______class allows you to format values as currency or percentages
NumberFormat
Value Ranges per Type: char
One symbol in single quotes 'a'
Integer Types: A very small number (-128 to +127)
byte
Integer Types
byte, (A very small number (-128 to +127)) short, (A small number (-32768 to +32767)) int, (A large number (-2,147,483,648 to +2,147,483,647))
There are eight fundamental data types in Java Four of them represent integers:
byte, short, int, long
int cansPerPack = 6; //declare and initialize what is the variable name?
cansPerPack
There are eight fundamental data types in Java One of them represents characters:
char
Operators can be combined into
complex expressions
In Java, we use the final modifier to declare a
constant
int is a
data type
Multiple variables can be created in one
declaration
If you are interested in the remainder, use remainder operator (%) to get the remainder after
dividing the second operand into the first.
Unless specified otherwise, white space is used to separate the
elements of the input.
You can not use symbols such as %, ? in a
variable name
int total; total is a
variable name
The DecimalFormat class can be used to format a floating point value in
various ways.
% as an operator means
remainder
You might need to ask for input (prompt for input) and then
save what was entered.
Scanner scan = new Scanner (System.in); Once created, the Scanner object can be used to invoke various input methods, such as:
scan.nextLine();
variable declaration ends with a
semicolon
Integer Types: A small number (-32768 to +32767)
short
The constructor of the DecimalFormat class takes a ______ that represents a pattern for the formatted number.
string
A variable is a name to a
temporary storage location
The nextLine method reads all of the input until
the end of the line is found.
If both operands to the division operator (/) are integers,
the result is an integer (no rounding).
A constant is a variable except that it holds
the same value during its entire existence.
The difference between the various numeric types is their size, and therefore
the values they can store
A Scanner object can be set up to read input from various sources, including the user
typing values on the keyboard.
By convention constant names are all in
uppercase.
The compiler will issue an error if you try to change the ________ of a constant.
value
You can use _ in a variable name
$
short size
16 bits
float size
32 bits
int size
32 bits
int cansPerPack = 6; //declare and initialize The initial value is
6
How many bits in a long?
64 bits
how many bits in a double?
64 bits
byte size
8 bits
Value Ranges per Type Floating Point Types float:
A huge number with decimal places
Predefined D_____F______ class allows you to format values based on a pattern.
DecimalFormat
Reading Input - Three step process step 1
Import the Scanner class from its 'package' java.util
There are eight fundamental data types in Java And one of them represents boolean values:
boolean
Value Ranges per Type: Floating Point Types double:
Much more precise, for heavy math
Variable Declaration includes
Name of a variable Type (or size) of a variable
Value Ranges per Type: true or false
boolean
Scanner scan = new Scanner (System.in); The new operator creates the
Scanner object
Reading Input - Three step process step 2
Setup an object of the Scanner class
Keyboard input is represented by the ______.__ object
System.in
Reading Input - Three step process step 3
Use methods of the new Scanner object to get input (save input)
A variable name must start with
a letter or the underscore
Each formatter object has a method called format that returns a string with the specified information in the
appropriate format
Arithmetic expressions compute numeric results and make use of the
arithmetic operators:
There are eight fundamental data types in Java Two of them represent floating point numbers:
float, double
The NumberFormat class has static methods that return a
formatter object
The Java standard class library contains classes that provide
formatting capabilities.
The Scanner class is part of the java.util class library, and must be ________ into a program to be used.
imported
Integer Types: A large number (-2,147,483,648 to +2,147,483,647)
int
int cansPerPack = 6; //declare and initialize what is the data type?
int
Methods nextInt and nextDouble read
integer and double from the keyboard.
Both DecimalFormat and NumberFormat are part of what package?
java.text
The Scanner class is part of the ____.____ class library, and must be imported into a program to be used.
java.util
The next method of the Scanner class reads the next a string from the
keyboard.
a huge integer type would be a
long
A variable must have a
name, a type, (and may be an initial value)
An expression is a combination of one or more
operators and operands
Use the 'assignment statement' ( with an '=' ) to
place a new value into a variable
Formatting Output It is often necessary to format values in certain ways so that they can be
presented properly.
types of storage
primary storage and secondary storage
Predefined Scanner class
provides convenient methods for reading input values of various types.
Scanner scan = new Scanner (System.in); creates a Scanner object that
reads from the keyboard: