Operator is a symbol which tells to the compiler to perform some operation. Java provides a rich set of operators do deal with various types of operations. Sometimes we need to perform arithmetic operations then we use plus (+) operator for addition, multiply(*) for multiplication etc.
Operators are always essential part of any programming language.
Java operators can be divided into following categories:
Arithmetic operators are used to perform arithmetic operations like: addition, subtraction etc and helpful to solve mathematical expressions. The below table contains Arithmetic operators.
Operator  Description 

+ 
adds two operands 
 
subtract second operands from first 
* 
multiply two operand 
/ 
divide numerator by denumerator 
% 
remainder of division 
++ 
Increment operator increases integer value by one 
 
Decrement operator decreases integer value by one 
Example:
Lets create an example to understand arithmetic operators and their operations.
class Arithmetic_operators1{
public static void main(String as[])
{
int a, b, c;
a=10;
b=2;
c=a+b;
System.out.println("Addtion: "+c);
c=ab;
System.out.println("Substraction: "+c);
c=a*b;
System.out.println("Multiplication: "+c);
c=a/b;
System.out.println("Division: "+c);
b=3;
c=a%b;
System.out.println("Remainder: "+c);
a=++a;
System.out.println("Increment Operator: "+a);
a=a;
System.out.println("decrement Operator: "+a);
}
}
Relational operators are used to test comparison between operands or values. It can be use to test whether two values are equal or not equal or less than or greater than etc.
The following table shows all relation operators supported by Java.
Operator  Description 

== 
Check if two operand are equal 
!= 
Check if two operand are not equal. 
> 
Check if operand on the left is greater than operand on the right 
< 
Check operand on the left is smaller than right operand 
>= 
check left operand is greater than or equal to right operand 
<= 
Check if operand on left is smaller than or equal to right operand 
Example:
In this example, we are using relational operators to test comparison like less than, greater than etc.
class Relational_operators1{
public static void main(String as[])
{
int a, b;
a=40;
b=30;
System.out.println("a == b = " + (a == b) );
System.out.println("a != b = " + (a != b) );
System.out.println("a > b = " + (a > b) );
System.out.println("a < b = " + (a < b) );
System.out.println("b >= a = " + (b >= a) );
System.out.println("b <= a = " + (b <= a) );
}
}
Logical Operators are used to check conditional expression. For example, we can use logical operators in if statement to evaluate conditional based expression. We can use them into loop as well to evaluate a condition.
Java supports following 3 logical operator. Suppose we have two variables whose values are: a=true and b=false.
Operator  Description  Example 

&& 
Logical AND  (a && b) is false 
 
Logical OR  (a  b) is true 
! 
Logical NOT  (!a) is false 
Example:
In this example, we are using logical operators. There operators return either true or false value.
class Logical_operators1{
public static void main(String as[])
{
boolean a = true;
boolean b = false;
System.out.println("a && b = " + (a&&b));
System.out.println("a  b = " + (ab) );
System.out.println("!(a && b) = " + !(a && b));
}
}
Bitwise operators are used to perform operations bit by bit.
Java defines several bitwise operators that can be applied to the integer types long, int, short, char and byte.
The following table shows all bitwise operators supported by Java.
Operator  Description 

& 
Bitwise AND 
 
Bitwise OR 
^ 
Bitwise exclusive OR 
<< 
left shift 
>> 
right shift 
Now lets see truth table for bitwise &
, 
and ^
a 
b 
a & b 
a  b 
a ^ b


0  0  0  0  0 
0  1  0  1  1 
1  0  0  1  1 
1  1  1  1  0 
The bitwise shift operators shifts the bit value. The left operand specifies the value to be shifted and the right operand specifies the number of positions that the bits in the value are to be shifted. Both operands have the same precedence.
Example:Lets create an example that shows working of bitwise operators.
a = 0001000
b = 2
a << b = 0100000
a >> b = 0000010
class Bitwise_operators1{
public static void main(String as[])
{
int a = 50;
int b = 25;
int c = 0;
c = a & b;
System.out.println("a & b = " + c );
c = a  b;
System.out.println("a  b = " + c );
c = a ^ b;
System.out.println("a ^ b = " + c );
c = ~a;
System.out.println("~a = " + c );
c = a << 2;
System.out.println("a << 2 = " + c );
c = a >> 2;
System.out.println("a >>2 = " + c );
c = a >>> 2;
System.out.println("a >>> 2 = " + c );
}
}
Assignment operators are used to assign a value to a variable. It can also be used combine with arithmetic operators to perform arithmetic operations and then assign the result to the variable. Assignment operator supported by Java are as follows:
Operator  Description  Example 

=  assigns values from right side operands to left side operand  a = b 
+=  adds right operand to the left operand and assign the result to left  a+=b is same as a=a+b 
=  subtracts right operand from the left operand and assign the result to left operand  a=b is same as a=ab 
*=  mutiply left operand with the right operand and assign the result to left operand  a*=b is same as a=a*b 
/=  divides left operand with the right operand and assign the result to left operand  a/=b is same as a=a/b 
%=  calculate modulus using two operands and assign the result to left operand  a%=b is same as a=a%b 
Example:
Lets create an example to understand use of assignment operators. All assignment operators have right to left associativity.
class Assignment_operators1{
public static void main(String as[])
{
int a = 30;
int b = 10;
int c = 0;
c = a + b;
System.out.println("c = a + b = " + c );
c += a ;
System.out.println("c += a = " + c );
c = a ;
System.out.println("c = a = " + c );
c *= a ;
System.out.println("c *= a = " + c );
a = 20;
c = 25;
c /= a ;
System.out.println("c /= a = " + c );
a = 20;
c = 25;
c %= a ;
System.out.println("c %= a = " + c );
c <<= 2 ;
System.out.println("c <<= 2 = " + c );
c >>= 2 ;
System.out.println("c >>= 2 = " + c );
c >>= 2 ;
System.out.println("c >>= 2 = " + c );
c &= a ;
System.out.println("c &= a = " + c );
c ^= a ;
System.out.println("c ^= a = " + c );
c = a ;
System.out.println("c = a = " + c );
}
}
There are few other operator supported by java language.
It is also known as ternary operator because it works with three operands. It is short alternate of ifelse statement. It can be used to evaluate Boolean expression and return either true or false value
epr1 ? expr2 : expr3
Example:
In ternary operator, if epr1 is true then expression evaluates after question mark (?) else evaluates after colon (:). See the below example.
class Conditional_operators1{
public static void main(String as[])
{
int a, b;
a = 20;
b = (a == 1) ? 30: 40;
System.out.println( "Value of b is : " + b );
b = (a == 20) ? 30: 40;
System.out.println( "Value of b is : " + b );
}
}
instanceOf
operatorIt is a java keyword and used to test whether the given reference belongs to provided type or not. Type can be a class or interface. It returns either true or false.
Example:
Here, we created a string reference variable that stores “studytonight”. Since it stores string value so we test it using isinstance operator to check whether it belongs to string class or not. See the below example.
class instanceof_operators1{
public static void main(String as[])
{
String a = "Studytonight";
boolean b = a instanceof String;
System.out.println( b );
}
}