Naming Conventions, Data Types and Operators ,JAVA
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Naming Conventions: Naming conventions specify the rules to be followed by a Java programmer while writing the names of packages, classes, methods etc.
· Package names are written in small letters.
e.g.: java.io, java.lang, java.awt etc
· Each word of class name and interface name starts with a capital
e.g.: Sample, AddTwoNumbers
· Method names start with small letters then each word start with a capital e.g.: sum (), sumTwoNumbers (), minValue () ·
.Variable names also follow the same above method rule
e.g.: sum, count, totalCount
· Constants should be written using all capital letters
e.g.: PI, COUNT
· Keywords are reserved words and are written in small letters.
e.g.: int, short, float, public, void
Data Types: The classification of data item is called data type. Java defines eight simple types of data. byte, short, int, long, char, float, double and boolean. These can be put in four groups: · Integer Data Types: These data types store integer numbers
Data Type | Memory size | Range |
Byte | 1 byte | -128 to 127 |
Short | 2 bytes | -32768 to 32767 |
Int | 4 bytes | -2147483648 to 2147483647 |
Long | 8 bytes | -9223372036854775808 to 9223372036854775807 |
e.g.: byte rno = 10; long x = 150L; L means forcing JVM to allot 8 bytes
· Float Data Types: These data types handle floating point numbers
Data Type | Memory size | Range |
Float | 4 bytes | -3.4e38 to 3.4e38 |
Double | 8 bytes | -1.7e308 to 1.7e308 |
e.g.: float pi = 3.142f;
double distance = 1.98e8;
· Character Data Type: This data type represents a single character. char data type in java uses two bytes of memory also called Unicode system. Unicode is a specification to include alphabets of all international languages into the character set of java.
Data Type | Memory size | Range |
Char | 2 bytes | 0 to 65535 |
e.g.: char ch = 'x';
· Boolean Data Type: can handle truth values either true or false
e.g.:- boolean response = true;
Operators: An operator is a symbol that performs an operation. An operator acts on variables called operands.
· Arithmetic operators: These operators are used to perform fundamental operations like addition, subtraction, multiplication etc.
Operator | Meaning | Example | Result |
+ | Addition | 3 + 4 | 7 |
- | Subtraction | 5 - 7 | -2 |
* | Multiplication | 5 * 5 | 25 |
/ | Division (gives quotient) | 14 / 7 | 2 |
% | Modulus (gives remainder) | 20 % 7 | 6 |
· Assignment operator: This operator (=) is used to store some value into a variable.
Simple Assignment | Compound Assignment |
x = x + y | x += y |
x = x – y | x -= y |
x = x * y | x *= y |
x = x y | x /= y |
· Unary operators: As the name indicates unary operator’s act only on one operand.
Operator | Meaning | Example | Explanation |
- | Unary minus | j = -k; | k value is negated and stored into j |
++ | Increment Operator | b++; ++b; | b value will be incremented by 1 (called as post incrementation) b value will be incremented by 1 (called as pre incrementation) |
-- | Decrement Operator | b--; --b; | b value will be decremented by 1 (called as post decrementation) b value will be decremented by 1 (called as pre decrementation) |
· Relational operators: These operators are used for comparison purpose.
Operator | Meaning | Example |
== | Equal | x == 3 |
!= | Not equal | x != 3 |
< | Less than | x < 3 |
> | Greater than | x > 3 |
<= | Less than or equal to | x <= 3 |
· Logical operators: Logical operators are used to construct compound conditions. A compound condition is a combination of several simple conditions.
Operator | Meaning | Example | Explanation |
&& | and operator | if(a>b && a>c) System.out.print(“yes”); | If a value is greater than b and c then only yes is displayed |
|| | or operator | if(a==1 || b==1) System.out.print(“yes”); | If either a value is 1 or b value is 1 then yes is displayed |
! | not operator | if( !(a==0) ) System.out.print(“yes”); | If a value is not equal to zero then only yes is displayed |
· Bitwise operators: These operators act on individual bits (0 and 1) of the operands. They act only on integer data types, i.e. byte, short, long and int.
Operator | Meaning | Explanation |
& | Bitwise AND | Multiplies the individual bits of operands |
| | Bitwise OR | Adds the individual bits of operands |
^ | Bitwise XOR | Performs Exclusive OR operation |
<< | Left shift | Shifts the bits of the number towards left a specified number of positions |
>> | Right shift | Shifts the bits of the number towards right a specified number of positions and also preserves the sign bit. |
>>> | Zero fill right shift | Shifts the bits of the number towards right a specified number of positions and it stores 0 (Zero) in the sign bit. |
~ | Bitwise complement | Gives the complement form of a given number by changing 0’s as 1’s and vice versa. |
· Ternary Operator or Conditional Operator (? :): This operator is called ternary because it acts on 3 variables. The syntax for this operator is:
Variable = Expression1? Expression2: Expression3;
First Expression1 is evaluated. If it is true, then Expression2 value is stored into variable otherwise Expression3 value is stored into the variable.
e.g.: max = (a>b) ? a: b;
Program 1: Write a program to perform arithmetic operations
//Addition of two numbers class AddTwoNumbers
{ public static void mian(String args[])
{ int i=10, j=20;
System.out.println("Addition of two numbers is : " + (i+j));
System.out.println("Subtraction of two numbers is : " + (i-j));
System.out.println("Multiplication of two numbers is : " + (i*j));
System.out.println("Quotient after division is : " + (i/j) );
System.out.println("Remainder after division is : " +(i%j) );
}
}
//Bitwise Operations
class Bits
{ public static void main(String args[])
{ byte x,y;
x=10; y=11;
System.out.println ("~x="+(~x));
System.out.println ("x & y="+(x&y));
System.out.println ("x | y="+(x|y));
System.out.println ("x ^ y="+(x^y));
System.out.println ("x<<2="+(x<<2));
System.out.println ("x>>2="+(x>>2));
System.out.println ("x>>>2="+(x>>>2));
}
}
Category: Data Types and Operators, Java, Naming Conventions
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