Objective:

Concept

Arithmetic Operators
Arithmetic operators are used in the mathematical expression. Following are some arithmetic operators:

The Basic Arithmetic Operators
The basic arithmetic operators are Addition, Subtraction, Multiplication, and Division. All behave the same, as you would expect for all numeric types.

Example:

Class MyMath {
        public static void main (String args[]) {
        int a = 1 + 1;
        int b = a * 3;
        int c =  b / 4;
        int d =  c - a;
        int e =  -d;

        System.out.println("a is: " + a);
        System.out.println("b is: " + b);
        System.out.println("c is: " + c);
        System.out.println("d is: " + d);
        System.out.println("e is: " + e);
       }

}

The Modulus Operator
The modulus operator (%) returns the remainder of a division operation. It can be applied to floating point type as well as integer types.

Examples:
Class MyModulus {
public static void main (String args[]){
int x = 42;
double y = 42.3;

System.out.println("x mode 10 = " + x % 10);
System.out.println("y mode 10 = " + y % 10);
}
}

Arithmetic Assignment Operators
These operators combine an arithmetic operation with an assignment. Statements like the following are quite common programming.

a = a + 4

This may also be written as:

a += 4;

Example:
class OpEquals {
        public static void main (String args[]){
                 int a = 2;
                 int b = 3;
                 int c = 4;

                 a += 5;
                 b *= 5;
                 c +=  a + b;
                 c %= 6;

                 System.out.println("a is = " +a);
                 System.out.println("b is = " +b);
                 System.out.println("c is = " +c);
}}

Increment and Decrement
The ++ and -- are java's increment and decrement operators. The increment operator increases its operand by one; the decrement operator decreases its operand by one;

x = x + 1;

It can also be written as by use of increment operator.   x++;

Similarly this statement: 

x = x - 1;

is equivalent to: x--;

Example

class IncDec {
         public static void main(String args[]){
                  int a = 2; 
                  int b = 3;
                  int c;
                  int d;
                  c = ++b;
                  d = a++;

                  System.out.println("a is = " + a);
                  System.out.println("b is = " + b);
                  System.out.println("c is = " + c);
                  System.out.println("d is = " + d);
}}

Relational Operator

The relational operator determine the relationship that one operand has to the other. Specially they determine equality and ordering.

The outcome of the operators is a Boolean value. The relational operators are normally used in the expression that control the if statement and the various loops statements.

int a = 4;
int b = 5;
boolean c = a<b;

In this case the result of a < b (which is false) is stored in the variable c.

or if (done == 0)
         if (done != 0)

Boolean / Logical Operators
The Boolean logical operators operate only on Boolean operands. All of the binary logical operators combine two Boolean values to form a resultant Boolean.

Example:

Class Boolean{
         public static void main (String args[]){
             boolean a = true;
             boolean b = false;
             boolean c = a | b;
             boolean d = a & b;
             boolean e = a ^ b;
             boolean f = (!a & b) | (a & |b);
             boolean g = !a;
             System.out.println("a is: " + a);
             System.out.println("b is: " + b);
             System.out.println("a ! b is: " + c);
             System.out.println("a & b is: " + d);
             System.out.println("a ^ b is: " + e);
             System.out.println("(!a & b) | (a  |b) is: " + f);
             System.out.println("!a is: " + g);
}}

The Assignment Operator
The assignment operator is the single equal sign, =. The Assignment has its general form as follows:

var = expression;
int x, y, z;
x = y = z = 10;
// set x, y and z to 10;

Type Casting
Type casting is a phenomenon in which the value of one data type is assigned to the variable of other data type (implicitly) provided these two types are compatible. By compatible we mean that it is possible to convert an int value to long variable but it is not possible to implicitly convert a long value to byte type. However we have to explicitly use cast to make the later case possible. Lets see at both these types.

Implicit Type Casting
When one type of data is assigned to the other type of variable, an automatic type conversion occurs with the following two conditions:

The two types are compatible.

The destination type is larger than the source type.

When these two conditions are met, an automatic type conversion takes place. For automatic conversion, the numeric types (including int and float) are compatible with each other. However these are not compatible with char or Boolean.

Example

class impConversion{
 public static void main (String args[]){
  byte b = 42;
  char c = 'a';
  short s = 1024;
  int i = 5000;
  float f = 5.67f;
  double d = 0.12345;

  double result = (f * b) + (i / c) - (d * s);

  System.out.println((f * b) + " + " + (i / c) + " - " + (d * s));
  System.out.println ("The Result is = " + result);
}}

Explicit Type casting
When you want to assign a larger type value to a smaller value, you cannot do it without explicitly casting it using cast operator. For example you want to assign an int value to a byte variable. This conversion sometimes called narrowing conversion, since you are explicitly making the value narrower to fit into the small size. To undergo such a conversion we use cast.

target variable = (target type) value

Note that: some information may be lost during that process. For example, when floating point value is assigned to an integer the fractional component is lost.

Example

class Expconversion{
        public static void main (String args[]){
        byte b;
        int i = 257;
        double d = 323.567;

        System.out.println ("Conversion of int to byte");
        b = (byte) i;
        System.out.println ("i and b " + i + " " + b);

        System.out.println ("Conversion of double to int");
        i = (int) d;
        System.out.println ("d and i " + d + " " + i);

        System.out.println ("Conversion of double to byte");
        b = (byte) d;
        System.out.println ("d and b " + d + " " + b);

}}