Computer programming 2 Lesson 5

Computer
Programming 2
Lesson 5 – JAVA DATATYPES
Prepared by: Analyn G. Regaton

DATATYPES
Variables are nothing but reserved memory
locations to store values. This means that
when you create a variable you reserve some
space in the memory.
Based on the data type of a variable, the
operating system allocates memory and
decides what can be stored in the reserved
memory. Therefore, by assigning different
data types to variables, you can store
integers, decimals, or characters in these
variables.

TWO DATA
TYPES
 Primitive Data Types
 Reference/Object Data Types

PRIMITIVE
DATATYPES
Primitive datatypes are predefined
by the language and named by a
keyword. Let us now look into the
eight primitive data types in detail.

EIGHT
PRIMITIVE
DATATYPES
 Byte
 Short
 Int
 Long
 Float
 Double
 Boolean
 Char

BYTE
 Byte data type is an 8-bit signed two's complement
integer
 Minimum value is -128 (-2^7)
 Maximum value is 127 (inclusive)(2^7 -1)
 Default value is 0
 Byte data type is used to save space in large arrays,
mainly in place of integers, since a byte is four times
smaller than an integer.
 Example: byte a = 100, byte b = -50

SHORT
 Short data type is a 16-bit signed two's
complement integer
 Minimum value is -32,768 (-2^15)
 Maximum value is 32,767 (inclusive) (2^15
-1)
 Short data type can also be used to save
memory as byte data type. A short is 2
times smaller than an integer
 Default value is 0.
 Example: short s = 10000, short r = -20000

INT
 Int data type is a 32-bit signed two's complement
integer.
 Minimum value is - 2,147,483,648 (-2^31)
 Maximum value is 2,147,483,647(inclusive) (2^31 -1)
 Integer is generally used as the default data type for
integral values unless there is a concern about
memory.
 The default value is 0
 Example: int a = 100000, int b = -200000

LONG
 Long data type is a 64-bit signed two's
complement integer
 Minimum value is -
9,223,372,036,854,775,808(-2^63)
 Maximum value is 9,223,372,036,854,775,807
(inclusive)(2^63 -1)
 This type is used when a wider range than int
is needed
 Default value is 0L
 Example: long a = 100000L, long b = -200000L

FLOAT
 Float data type is a single-precision 32-bit IEEE
754 floating point
 Float is mainly used to save memory in large
arrays of floating point numbers
 Default value is 0.0f
 Float data type is never used for precise values
such as currency
 Example: float f1 = 234.5f

DOUBLE
 double data type is a double-precision 64-bit
IEEE 754 floating point
 This data type is generally used as the default
data type for decimal values, generally the
default choice
 Double data type should never be used for
precise values such as currency
 Default value is 0.0d
 Example: double d1 = 123.4

BOOLEAN
 boolean data type represents one bit of
information
 There are only two possible values: true
and false
 This data type is used for simple flags
that track true/false conditions
 Default value is false
 Example: boolean one = true

CHAR
 char data type is a single 16-bit Unicode
character
 Minimum value is 'u0000' (or 0)
 Maximum value is 'uffff' (or 65,535
inclusive)
 Char data type is used to store any
character
 Example: char letterA = 'A'

REFERENCE
DATATYPES
 Reference variables are created using defined
constructors of the classes. They are used to access
objects. These variables are declared to be of a
specific type that cannot be changed. For example,
Employee, Puppy, etc.
 Class objects and various type of array variables come
under reference datatype.
 Default value of any reference variable is null.
 A reference variable can be used to refer any object of
the declared type or any compatible type.
 Example: Animal animal = new Animal("giraffe");

JAVA
LATERALS
 A literal is a source code representation of a fixed value.
They are represented directly in the code without any
computation.
 Literals can be assigned to any primitive type variable. For
example −
 byte, int, long, and short can be expressed in decimal(base
10), hexadecimal(base 16) or octal(base 8) number systems
as well.

JAVA
LATERALS
 Prefix 0 is used to indicate octal, and prefix 0x indicates
hexadecimal when using these number systems for literals. For
example −
 String literals in Java are specified like they are in most other
languages by enclosing a sequence of characters between a pair of
double quotes. Examples of string literals are –
 String and char types of literals can contain any Unicode
characters. For example −

Computer programming 2 Lesson 5

Computer programming 2 Lesson 5

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Computer programming 2 Lesson 5