JAVA PROGRAMMING : Data types

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JAVA PROGRAMMING : Data types
By
Dr.T.Abirami
Associate Professor
Department of IT
Kongu Engineering College Perundurai
2/3/2021

Program Structure
Documentation Section - suggested
Package Statement - optional
Import Statement - optional
Interface Statement - optional
Main method class - Essential
{ main method definition }
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Dr.T.Abirami/Department of IT

Dr.T.Abirami/Department of IT 3
package util;
Import java.util.Date

Java Variables
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Syntax
 datatype variable = value;
int myNum = 5;
float myFloatNum = 5.99f;
char myLetter = 'D';
boolean myBool = true;
String myText = "Hello";
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Data type
 Data type specifies the size and type of
values that can be stored in an identifier.
 Different data types allow you to select
the type appropriate to the needs of the
application.

Data Types

Java Data Types
Data types are divided into two groups:
 Primitive data types
 - includes byte, short, int, long, float, double,
boolean and char
 Non-primitive data types
 - such as String, Arrays and Classes
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Java Data Types
Data Type Size Description
byte 1 byte Stores whole numbers from -128 to 127
short 2 bytes
Stores whole numbers from -32,768 to
32,767
int 4 bytes
Stores whole numbers from -2,147,483,648
to 2,147,483,647
long 8 bytes
Stores whole numbers from -
9,223,372,036,854,775,808 to
9,223,372,036,854,775,807
float 4 bytes
Stores fractional numbers. Sufficient for
storing 6 to 7 decimal digits
double 8 bytes
Stores fractional numbers. Sufficient for
storing 15 decimal digits
boolean 1 bit Stores true or false values
char 2 bytes
Stores a single character/letter or ASCII
values
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Range Calculation
 The range of values is calculated as
−(2n−1) to (2n−1)−1;
 where n is the number of bits required.
For example,
the byte data type requires 1 byte = 8 bits.
Therefore, the range of values that can be
stored in the byte data type is
−(28−1) to (28−1)−1
= −27 to (27) -1
= −128 to 127

Integer
 Integer types can hold whole numbers.
Ex: such as 123 and −96.
Type Size Range of values that can be stored
byte 1 byte −128 to 127
short 2 bytes −32768 to 32767
int 4 bytes −2,147,483,648 to 2,147,483,647
long 8 bytes
9,223,372,036,854,775,808 to
9,223,372,036,854,755,807

Integer Types
 byte myNum = 100;
System.out.println(myNum);
 short myNum = 5000;
 int myNum = 100000;
 long myNum = 15000000000L;
Note:you should end the value with an "L"
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Floating Point
 It is used to represent numbers with a
fractional part.
 Single precision floating point numbers
occupy 4 bytes and
 Double precision floating point numbers
occupy 8 bytes.
There are two subtypes:
Type Size
Range of values that can
be stored
float 4 bytes 3.4e−038 to 3.4e+038
double 8 bytes 1.7e−308 to 1.7e+038

General Terms of fractional nos
(-1)Sign × Significand × BaseExponent 1.2345=12345x10-4
Single Precision:
Single Precision is a format proposed by IEEE for representation of
floating-point number. It occupies 32 bits in computer memory.
Range of numbers in single precision : 2^(-126) to 2^(+127)

 Double Precision:
Double Precision is also a format given by
IEEE for representation of floating-point
number. It occupies 64 bits in computer
memory.

General Terms of fractional nos
Range of numbers in double precision : 2^(-1022) to 2^(+1023)

Floating Point Types
The float data type can store fractional numbers from 3.4e−038 to 3.4e+038.
Note that you should end the value with an "f":
 float myNum = 5.75f;
 double myNum = 19.99d;
 The precision of a floating point value indicates how many digits the
value can have after the decimal point.
 The precision of float is only six or seven decimal digits,
 while double variables have a precision of about 15 digits.
 Therefore it is safer to use double for most calculations.
 A floating point number can also be a scientific number with an "e" to
indicate the power of 10:
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Scientific Notation
 E is used to mean "10 to the power of."
 For example,
1.314E+1 means
1.314 * 101 which is 13.14.

Example : to indicate the power of 10:scientific
number with an "e"
 float f1 = 35e3f;
 double d1 = 12E4d;
System.out.println(f1);
System.out.println(d1);
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Booleans
 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;

Booleans
boolean isJavaFun = true;
boolean isFishTasty = false;
System.out.println(isJavaFun); // Outputs true
System.out.println(isFishTasty); // Outputs false
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Ascii
 It stands for American Standard code for
information interchange.
 It uses 8-bit encoding.
 ASCII uses 7 bits to represent a character.
 By using 7 bits, - > maximum of 2^7 (= 128)
distinct combinations*.
 Which means that we can represent 128
characters maximum.
Why 7 bits not 8 bits (1 byte)
 The last bit (8th) is used for avoiding errors as
parity bit.

ASCII
 ASCII characters are printable characters
of the alphabet
 such as abc, ABC, 123, ?&!, etc.
 The others are control characters such as
carriage return, line feed, tab, etc
binary representation of a few characters in ASCII:
0100101 -> % (Percent Sign - 37)
1000001 -> A (Capital letter A - 65)
1000010 -> B (Capital letter B - 66)
1000011 -> C (Capital letter C - 67)
0001101 -> Carriage Return (13)
ASCII was meant for English only.
what about the others needing a completely different
alphabet? Greek? Russian? Polish? Chinese and the likes?

ASCII Extended - Unicode
 Unicode Transformation Format
 Encodings: UTF-7, UTF-8, UTF-16, and UTF-32
 UTF-8 and UTF-16 are variable length encodings.
 In UTF-8, a character may occupy a minimum of 8
bits.
 In UTF-16, a character length starts with 16 bits.
 UTF-32 is a fixed length encoding of 32 bits.
 UTF-8 uses the ASCII set for the first 128
characters. - ASCII text is also valid in UTF-8.
Unicode represents most written languages in the world while ASCII
does not.

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'

Why char uses 2 byte in java and
what is u0000 ?
 It is because java uses Unicode system
not ASCII code system.
 The u0000 is the lowest range of Unicode
system.

Characters
 char myGrade = 'B';
System.out.println(myGrade);
 char a = 65, b = 66, c = 67;
System.out.println(a);
System.out.println(b);
System.out.println(c);
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Char Numb
er
Description
0 - 31 Control characters
(see below)
32 spaceTry it
! 33 exclamation
markTry it
" 34 quotation markTry
it
# 35 number signTry it
$ 36 dollar signTry it
% 37 percent signTry it
& 38 ampersandTry it
' 39 apostropheTry it
( 40 left parenthesisTry
it
) 41 right
parenthesisTry it
A 65 uppercase ATry it
B 66 uppercase BTry it
C 67 uppercase CTry it
D 68 uppercase DTry it
E 69 uppercase ETry it
F 70 uppercase FTry it
G 71 uppercase GTry it
H 72 uppercase HTry it
I 73 uppercase ITry it
J 74 uppercase JTry it
K 75 uppercase KTry it
L 76 uppercase LTry it
M 77 uppercase MTry it
N 78 uppercase NTry it
O 79 uppercase OTry it
P 80 uppercase PTry it
Q 81 uppercase QTry it
R 82 uppercase RTry it
S 83 uppercase STry it
T 84 uppercase TTry it
U 85 uppercase UTry it
V 86 uppercase VTry it
W 87 uppercase WTry it
X 88 uppercase XTry it
Y 89 uppercase YTry it
Z 90 uppercase ZTry it
l 108 lowercase lTry it
m 109 lowercase mTry it
n 110 lowercase nTry it
o 111 lowercase oTry it
p 112 lowercase pTry it
q 113 lowercase qTry it
r 114 lowercase rTry it
s 115 lowercase sTry it
t 116 lowercase tTry it
u 117 lowercase uTry it
v 118 lowercase vTry it
w 119 lowercase wTry it
x 120 lowercase xTry it
y 121 lowercase yTry it
z 122 lowercase zTry it
{ 123 left curly braceTry
it
| 124 vertical barTry it
} 125 right curly braceTry
it
~ 126 tilde
ASCII Printable Characters

* 42 asteriskTry it
+ 43 plus signTry it
, 44 commaTry it
- 45 hyphenTry it
. 46 periodTry it
/ 47 slashTry it
0 48 digit 0Try it
1 49 digit 1Try it
2 50 digit 2Try it
3 51 digit 3Try it
4 52 digit 4Try it
5 53 digit 5Try it
6 54 digit 6Try it
7 55 digit 7Try it
8 56 digit 8Try it
9 57 digit 9Try it
: 58 colonTry it
; 59 semicolonTry it
< 60 less-thanTry it
= 61 equals-toTry it
> 62 greater-thanTry it
? 63 question markTry
it
@ 64 at signTry it
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[ 91 left square
bracketTry it
92 backslashTry it
] 93 right square
bracketTry it
^ 94 caretTry it
_ 95 underscoreTry it
` 96 grave accentTry it
a 97 lowercase aTry it
b 98 lowercase bTry it
c 99 lowercase cTry it
d 100 lowercase dTry it
e 101 lowercase eTry it
f 102 lowercase fTry it
g 103 lowercase gTry it
h 104 lowercase hTry it
i 105 lowercase iTry it
j 106 lowercase jTry it
k 107 lowercase kTry it
ASCII Printable Characters

JAVA PROGRAMMING : Data types

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