'while' iteration statements

Iteration statement creates loops. A loop repeatedly executes the same set of instructions until a termination condition is met. Iteration statements are another type of 'Control Flow' statements.


 Program to demonstrate the 'while' loop                                                                                                                                

'while' loop executes the statements in its block repetitively as long as the condition expression is true.

class WhileLoop
{
   public static void main(String args[])
   {

      int i=1;

      while(i<6)    //This loop will be executed repeatedly until the value of i is less than 6
      {
         System.out.println("The value of i is "+i);
         i++;
      }

    }

 }

Output of this program:

The value of i is 1
The value of i is 2
The value of i is 3
The value of i is 4
The value of i is 5

'while' loop executes the statements inside its block repeatedly until the value of i is less than 6 in this example. So to start with 'while(i<6) i.e. while(1<6) which is true, hence it enters into the while block and prints "The value of i is 1" and then executes i++; i.e. it increments the value of i by 1. So the value of i now is 2. The loop then gets repeated with while(i<6) i.e. while(2<6) which is true -> hence prints "The value of i is 2", while(3<6) which is true -> hence prints "The value of i is 3", while(4<6) which is true -> hence prints "The value of i is 4", while(5<6) which is true -> hence prints "The value of i is 5" and while(6<6) which is false hence wont enter into the while block as the condition is false.
Program to demonstrate the infinite times executed while loop

'while' block will get executed infinite times if the condition expression is always true

class InfiniteWhileLoop
{
   public static void main(String args[])
   {

      int i=1;

      while(i<6)
      {
         System.out.println("The value of i is "+i);
      }

    }

 }

Output of this program:

"The value of i is 1" will be printed infinite times.

In this example, we've not incremented the value of i by 1 as we did in the earlier example. As a result the value of i is always 1. Since while(i<6) i.e. while(1<6) is always true, the statement "The value of i is 1" inside the while loop will be printed infinite times.
Program to demonstrate a never executed while loop

'while' block wont be executed at least single time when the condition expression is false.

class NeverExecutedWhileLoop
{
   public static void main(String args[])
   {

      int i=6;

      while(i<6)
      {
         System.out.println("The value of i is "+i);
      }

    }

 }

Output of this program:

[No output] - Since while(i<6) i.e. while(6<6) is false, the statements inside the while block wont be executed at least once.
Finding the mid value of 1 and 11 using the 'while' loop

class ExampleWhileLoop
{
   public static void main(String args[])
   {

      int i=1,j=11;

      while(++i<--j);   //There are no statements in the while loop, hence we have not used the flower braces.

      System.out.println("The mid value of 1 and 11 is "+i);

    }

 }

The output of this program:

The mid value of 1 and 11 is 6
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