JAVA Operators

Java provides a rich set of operators to manipulate variables. We can divide all the Java operators into the following groups:

• Arithmetic Operators
• Relational Operators
• Bitwise Operators
• Logical Operators
• Assignment Operators

The Arithmetic Operators:

Arithmetic operators are used in mathematical expressions in the same way that they are used in algebra. The following table lists the arithmetic operators:

Assume integer variable A holds 10 and variable B holds 20 then:

Show Examples

Operator	Description	Example
+	Addition - Adds values on either side of the operator	A + B will give 30
-	Subtraction - Subtracts right hand operand from left hand operand	A - B will give -10
*	Multiplication - Multiplies values on either side of the operator	A * B will give 200
/	Division - Divides left hand operand by right hand operand	B / A will give 2
%	Modulus - Divides left hand operand by right hand operand and returns remainder	B % A will give 0
++	Increment - Increase the value of operand by 1	B++ gives 21
--	Decrement - Decrease the value of operand by 1	B-- gives 19

class Test {

public static void main(String args[]) {

   int a = 10;

   int b = 20;

   int c = 25;

   int d = 25;

   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) );

   System.out.println("c % a = " + (c % a) );

   System.out.println("a++   = " +  (a++) );

   System.out.println("b--   = " +  (a--) );

   // Check the difference in d++ and ++d

   System.out.println("d++   = " +  (d++) );

   System.out.println("++d   = " +  (++d) );

}

} 

The Relational Operators:

There are following relational operators supported by Java language

Assume variable A holds 10 and variable B holds 20 then:

Operator	Description	Example
==	Checks if the value of two operands are equal or not, if yes then condition becomes true.	(A == B) is not true.
!=	Checks if the value of two operands are equal or not, if values are not equal then condition becomes true.	(A != B) is true.
>	Checks if the value of left operand is greater than the value of right operand, if yes then condition becomes true.	(A > B) is not true.
<	Checks if the value of left operand is less than the value of right operand, if yes then condition becomes true.	(A < B) is true.
>=	Checks if the value of left operand is greater than or equal to the value of right operand, if yes then condition becomes true.	(A >= B) is not true.
<=	Checks if the value of left operand is less than or equal to the value of right operand, if yes then condition becomes true.	(A <= B) is true.

The following simple example program demonstrates the relational operators. Copy and paste following Java program in Test.java file and compile and run this program. :

class Test { public static void main(String args[]) {    int a = 10;    int b = 20;    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) ); } }

The Bitwise Operators:

Java defines several bitwise operators which can be applied to the integer types, long, int, short, char, and byte.

Bitwise operator works on bits and perform bit by bit operation. Assume if a = 60; and b = 13; Now in binary format they will be as follows:

a = 0011 1100

b = 0000 1101

-----------------

a&b = 0000 1100

a|b = 0011 1101

a^b = 0011 0001

~a  = 1100 0011

The following table lists the bitwise operators:

Assume integer variable A holds 60 and variable B holds 13 then:

Operator	Description	Example
&	Binary AND Operator copies a bit to the result if it exists in both operands.	(A & B) will give 12 which is 0000 1100
|	Binary OR Operator copies a bit if it exists in eather operand.	(A | B) will give 61 which is 0011 1101
^	Binary XOR Operator copies the bit if it is set in one operand but not both.	(A ^ B) will give 49 which is 0011 0001
~	Binary Ones Complement Operator is unary and has the efect of 'flipping' bits.	(~A ) will give -60 which is 1100 0011
<<	Binary Left Shift Operator. The left operands value is moved left by the number of bits specified by the right operand.	A << 2 will give 240 which is 1111 0000
>>	Binary Right Shift Operator. The left operands value is moved right by the number of bits specified by the right operand.	A >> 2 will give 15 which is 1111
>>>	Shift right zero fill operator. The left operands value is moved right by the number of bits specified by the right operand and shifted values are filled up with zeros.	A >>>2 will give 15 which is 0000 1111

The Logical Operators:

The following table lists the logical operators:

Assume boolean variables A holds true and variable B holds false then:

Operator	Description	Example
&&	Called Logical AND operator. If both the operands are non zero then then condition becomes true.	(A && B) is false.
||	Called Logical OR Operator. If any of the two operands are non zero then then condition becomes true.	(A || B) is true.
!	Called Logical NOT Operator. Use to reverses the logical state of its operand. If a condition is true then Logical NOT operator will make false.	!(A && B) is true.

The Assignment Operators:

There are following assignment operators supported by Java language:

Operator	Description	Example
=	Simple assignment operator, Assigns values from right side operands to left side operand	C = A + B will assigne value of A + B into C
+=	Add AND assignment operator, It adds right operand to the left operand and assign the result to left operand	C += A is equivalent to C = C + A
-=	Subtract AND assignment operator, It subtracts right operand from the left operand and assign the result to left operand	C -= A is equivalent to C = C - A
*=	Multiply AND assignment operator, It multiplies right operand with the left operand and assign the result to left operand	C *= A is equivalent to C = C * A
/=	Divide AND assignment operator, It divides left operand with the right operand and assign the result to left operand	C /= A is equivalent to C = C / A
%=	Modulus AND assignment operator, It takes modulus using two operands and assign the result to left operand	C %= A is equivalent to C = C % A
<<=	Left shift AND assignment operator	C <<= 2 is same as C = C << 2
>>=	Right shift AND assignment operator	C >>= 2 is same as C = C >> 2
&=	Bitwise AND assignment operator	C &= 2 is same as C = C & 2
^=	bitwise exclusive OR and assignment operator	C ^= 2 is same as C = C ^ 2
|=	bitwise inclusive OR and assignment operator	C |= 2 is same as C = C | 2

Misc Operators

There are few other operators supported by Java Language.

Conditional Operator ( ? : ):

Conditional operator is also known as the ternary operator. This operator consists of three operands and is used to evaluate boolean expressions. The goal of the operator is to decide which value should be assigned to the variable. The operator is written as :

variable x = (expression) ? value if true : value if false

Following is the example:

public class Test {    public static void main(String args[]){       int a , b;       a = 10;       b = (a == 1) ? 20: 30;       System.out.println( "Value of b is : " +  b );       b = (a == 10) ? 20: 30;       System.out.println( "Value of b is : " + b );    } }

This would produce following result:

Value of b is : 30 Value of b is : 20

true

Precedence of Java Operators:

Operator precedence determines the grouping of terms in an expression. This affects how an expression is evaluated. Certain operators have higher precedence than others; for example, the multiplication operator has higher precedence than the addition operator:

For example x = 7 + 3 * 2; Here x is assigned 13, not 20 because operator * has higher precedenace than + so it first get multiplied with 3*2 and then adds into 7.

Here operators with the highest precedence appear at the top of the table, those with the lowest appear at the bottom. Within an expression, higher precedenace operators will be evaluated first.

Category	Operator	Associativity
Postfix	() [] . (dot operator)	Left to right
Unary	++ - - ! ~	Right to left
Multiplicative	* / %	Left to right
Additive	+ -	Left to right
Shift	>> >>> <<	Left to right
Relational	> >= < <=	Left to right
Equality	== !=	Left to right
Bitwise AND	&	Left to right
Bitwise XOR	^	Left to right
Bitwise OR	|	Left to right
Logical AND	&&	Left to right
Logical OR	||	Left to right
Conditional	?:	Right to left
Assignment	= += -= *= /= %= >>= <<= &= ^= |=	Right to left
Comma	,	Left to right

Array is a data structure capable to hold data of similar data types. Every language comes with its own rules for arrays. For example, JavaScript and VBScript comes its own set of rules, quiet different from Java. Arrays of Java are similar to C/C++.

Properties of Arrays

Following are the properties of arrays as accepted by the Java compiler.

1. Arrays stores similar data types. That is, array can hold data of same data type values. This is one of the limitations of arrays compared to other data structures.
2. Each value stored, in an array, is known as an element and all elements are indexed. The first element added, by default, gets 0 index. That is, the 5th element added gets an index number of 4.
3. Elements can be retrieved by their index number.
4. Array elements are stored in contiguous (continuous) memory locations.
5. Once array is created, its size is fixed. That is, at runtime if required, more elements cannot be added. This is another limitation of arrays compared to other data structures.
6. One array name can represent multiple values. Array is the easiest way to store a large quantity of data of same data types. For example, to store the salary of 100 employees, it is required to declare 100 variables. But with arrays, with one array name all the 100 employees salaries can be stored.
7. Arrays can be multidimensional.
8. At the time of creation itself, array size should be declared (array initialization does not require size).
9. In Java, arrays are predefined objects. With methods, the array elements can be manipulated.

Java supports two types of castings – primitive data type casting.

Java data type casting comes with 3 flavors.

1. Implicit casting
2. Explicit casting

1. Implicit casting (widening conversion)

A data type of lower size (occupying less memory) is assigned to a data type of higher size. This is done implicitly by the JVM. The lower size is widened to higher size. This is also named as automatic type conversion.

Examples:

        int x = 10;                    // occupies 4 bytes

        double y = x;                  // occupies 8 bytes

        System.out.println(y);         // prints 10.0

In the above code 4 bytes integer value is assigned to 8 bytes double value.

2. Explicit casting (narrowing conversion)

A data type of higher size (occupying more memory) cannot be assigned to a data type of lower size. This is not done implicitly by the JVM and requires explicit casting; a casting operation to be performed by the programmer. The higher size is narrowed to lower size.

       double x = 10.5;             // 8 bytes

       int y = x;                   // 4 bytes ;  raises compilation error

In the above code, 8 bytes double value is narrowed to 4 bytes int value. It raises error. Let us explicitly type cast it.

       double x = 10.5;                 

       int y = (int) x;

The double x is explicitly converted to int y. The thumb rule is, on both sides, the same data type should exist.

3. Boolean casting

A boolean value cannot be assigned to any other data type. Except boolean, all the remaining 7 data types can be assigned to one another either implicitly or explicitly; but boolean cannot. We say, boolean is incompatible for conversion. Maximum we can assign a boolean value to another boolean.

Following raises error.

       boolean x = true;

       int y = x;                    // error

       boolean x = true;

       int y = (int) x;           // error

byte –> short –> int –> long –> float –> double

In the above statement, left to right can be assigned implicitly and right to left requires explicit casting. That is, byte can be assigned to short implicitly but short to byte requires explicit casting.