Java Programs

//program using if statement

class ife {
   public static void main(String ar[])  {

       int month=2,year=2016;
       int days=0;

       if((month == 2) && ((year % 4)==0))  days = 29;  //find if given year is leap year
       if((month == 2) && ((year % 4)!=0))  days = 28;   //f given year is not leap year

       if(month == 1 || month == 3 || month == 5 || month == 7 || month == 8 ||month == 10 ||month == 12)
                days = 31;

       if(month == 4 || month == 6 || month == 9 || month == 11) //months has 30 days in it
                days = 30;

       System.out.println("Month="+month+" year="+year+" has "+days+" days");
    }
}

SWITCH Statement
============
It is a better way to represent multi if...else...if...else... statements.
It checks value of expression which is given in bracket of switch statement.
syntax is :
switch (exp)
{
  case value1:
                some valid java statements
                 break;
  case value2:
                some valid java statements
                 break;
  case value3:
                some valid java statements
                 break;
   .
   .
   .
   default:
                 some valid java statements
}

break statement is optional.
If you not use break statement then execution is on going with other cases 
till break statement occurs or end of switch statement.
You can use switch statement in between outer switch statement (nesting is allowed).

eg.

//example of switch statement

class swit {
   public static void main(String ar[]) {
    int i = 7;
    switch(i)
    {
	case 1: System.out.println("Sunday");
                            break;
	case 2: System.out.println("Monday");
                            break;
	case 3: System.out.println("Tuesday");
                            break;
	case 4: System.out.println("Wedensday");
                            break;
	case 5: System.out.println("Thursday");
                            break;
	case 6: System.out.println("Friday");
                            break;
	case 7: System.out.println("Saturday");
                            break;
	default: System.out.println("No such day!");
    }
}
}

another form of switch statement:

//example of switch statement

class swit1 {
   public static void main(String ar[]) {
    int i = 5;
    switch(i)
    {
	case 11: 
	case 12: 
	case 1: 
	case 2: System.out.println("Its Winter");
                            break;
	case 3: 
	case 4: 
	case 5: 
	           System.out.println("oh no!! Summer");
                            break;
	case 6: 
	case 7: 
	case 8: 
	case 9: 
	            System.out.println("Aah! Rainy days");
                            break;
	case 10: 
	            System.out.println("October Heat!");
                            break;
    }
}
}