Java provides rich operator environment. Most of
its operators can be divided into the following groups: arithmetic, relational,
logical.
Arithmetic Operators
Arithmetic operators are used in mathematical expression
in the same way that they are used in algebra. The following table lists
the arithmetic operators:
Operator 
Result 
+ 
Addition 
 
Subtraction 
* 
Multiplication 
/ 
Division 
% 
Modulus 
++ 
Increment 
+= 
Addition assignment 
= 
Subtraction assignment 
*= 
Multiplication assignment 
/= 
Division assignment 
%= 
Modulus assignment 
 
Decrement 
The operands of the arithmetic operators must be
of numeric type. You cannot use them on boolean types, but you can use
them on char types, since the char type in Java is, essentially, a subset
of int.
class example1 {
public static void main(String args[]) {
System.out.println("Integer Arithmetic");
int a = 1 + 1;
int b = a * 3;
int c = b / 4;
int d = c  a;
int e = d;
System.out.println("a = " + a);
System.out.println("b = " + b);
System.out.println("c = " + c);
System.out.println("d = " + d);
System.out.println("e = " + e);
System.out.println("\nFloating Point Arithmetic");
double da = 1 + 1;
double db = da * 3;
double dc = db / 4;
double dd = dc  a;
double de = dd;
System.out.println("da = " + da);
System.out.println("db = " + db);
System.out.println("dc = " + dc);
System.out.println("dd = " + dd);
System.out.println("de = " + de);
}
} 
when you run this program you will see the following
output
Integer Arithmetic
a = 2
b = 6
c = 1
d = 1
e = 1
Floating Point Arithmetic
da = 2
db = 6
dc = 1.5
dd = 0.5
de = 0.5
The Modulus Operator
The modulus operator, %, return the remainder of
a division operation. It can be applied to floatingpoint types as well
as integer types. The following program demonstrates.
class example2 {
public static void main(String args[]) {
int x = 42;
double y = 42.3;
System.out.println("x mod 10 = " + x % 10);
System.out.println("y mod 10 = " + y % 10);
}
} 
when you run this program you will get following
output:
x mod 10 = 2
y mod 10 = 2.299999999999997
Arithmetic Assignment Operators
Java provides special operators that can be used
to combine an arithmetic operation with an assignment. As you probably
know, statements like the following are quite common in programming.
a = a + 4;
In Java, you can write this statement as shown here
a += 4;
This version uses the += assignment operator. Both
statements performs the same action: they increase the value of a by 4;here
are some more examples.
a = a % 2; can be written as a %= 2;
b = b * 3; can be written as b *= 3;
c = c / 5; can be written as c /= 5;
d = d  7; can be written as d = 7;
Increment and decrement
The ++ and the – are Java’s increment and decrement
operators. The increment operator increases its operand by one. The decrement
operator decreases its operand by one. For example, this statement
x = x + 1; can be rewritten like this by use
of increment operator. x++;
Similarly, this statement x = x  1; is equivalent
to x;
These operators are unique in that they can appear
both in postfix form, where they follow the operand as just shown, and
prefix form, where they precede the operand.
class example3 {
public static void main(String args[]) {
int a = 23;
int b = 5;
System.out.println("a & b : " + a + "
" + b);
a += 30;
b *= 5;
System.out.println("after arithmetic assignment
a & b: "+a+" "+b);
a++;
b;
System.out.println("after increment &
decrement a & b: "+a+" "+b);
}
} 
The output of this program follows
a & b : 23 5
after arithmetic assignment a & b : 53 25
after increment & decrement a & b : 54 24
Relational Operators
The relational operator determine the relationship
that one operand has to the other. Specifically, they determine equality
and ordering. The relational operators are shown here.
Operator 
Result 
== 
Equal to 
!= 
Not equal to 
> 
Greater than 
< 
Less than 
>= 
Greater than or equal to 
<= 
Less than or equal to 
The outcome of these operation is a boolean value.
The relational operators are most frequently used in the expressions that
control the if statement and the various loop statements.
Any type in Java, including integers, floatingpoint
numbers, characters, and Boolean can be compared using the equality test,
==, and the inequality test, !=. Notice that in Java equality is denoted
with two equal signs, not one. ( single equal sign is the assignment operator.)
eg:
int a = 4;
int b = 1;
boolean c = a < b;
In this case, the result of a < b (which is false)
is stored in c.
Boolean Logical operators
The boolean logical operators shown here operate
only on boolean operands. All of the binary logical operators combine two
boolean values to form a resultant boolean value.
Operator 
Result 
&& 
AND 
 
OR 
! 
Logical unary NOT 
== 
Equals to 
!= 
Not Equals to 
?: 
Ternary ifthenelse 
class example4 {
public static void main(String args[]) {
boolean b;
b = (2 > 3) && (3 < 2);
System.out.println("b = "+b);
b = false  true ;
System.out.println("b = "+b);
}
} 
the output of the program is shown here.
b = false
b = true
The ? , : Operator
Java includes a special ternary (threeway) operator
that can replace certain types of ifthenelse statement. This operator
is the ?. The ? has this general form.
expression1 ? expression2 : expression3
Here, expression1 can be any expression that evaluates
to a boolean value. If expression1 is true, then expression2 is evaluated;
otherwise, expression3 is evaluated. The result of the ? operation is that
of the expression evalueated. Both expression2 and expression3 are required
to return the same type, which can’t be void.
Eg: int i=20;
int j=30;
int max = ( i > j ) ? x : j;
this section checks for the condition, if i is greater
than j then value of i is asigned to max else value of j is assigned to
max.
Class example5 {
public static void main(String args[]) {
int i,k;
i = 10;
k = i < 0 ? i : i; // get absolute value
of I
System.out.print("Absolute value of ");
System.out.println(i + " is " + k);
i = 10;
k = i < 0 ? i : i; //get absolute value
of I
System.out.print("Absolute value of ");
System.out.println(i + " is " + k);
}
} 
The output generated by program is shown here.
Absolute value of 10 is 10
Absolute value of 10 is 10
Operator Precedence
Highest




()

[]

.


++



~

!

*

/

%


+





>

>=

<

<=

==

!=



&




^




&&









?:




=

op=



Lowest




Notice that the first row shows items that you may
not normally think of as operators:
Parentheses, square brackets, and the dot operators,
Parentheses are used to alter the precedence of an operation.
Using Parentheses
Parentheses raise the precedence of the operations
that are inside them. This is often necessary to obtain the result you
desire. For example the following expression :
a + b * 3;
This expression first multiplies b with 3 then adds
it to a. However the result can differ by putting the parentheses around
a + b.
( a + b ) * 3;
This expression first solves brackets i.e. first
adds a to b then result is multiplied to 3.
