Loops in Java

 

Loops in Java

Looping in programming languages is a feature which facilitates the execution of a set of instructions/functions repeatedly while some condition evaluates to true.

While loop:-

A while loop is a control flow statement that allows code to be executed repeatedly based on a given Boolean condition. 

The while loop can be thought of as a repeating if statement.

Syntax :

while (boolean condition)

{

   loop statements...

}

Flowchart:-

Example:-

This program will try to print “Hello World” 5 times.

// Java program to illustrate while loop.    class Demo {      public static void main(String args[])         {                     int i = 1;                      while (i < 6)                                     {                         System.out.println("Hello World");                          i++;                   }         } }

Output:

Hello World
Hello World
Hello World
Hello World
Hello World
Example 2:-
// Java program to illustrate while loop
class Whileloopdemo
{
        public static void main(String args[])
        {
            int x = 1;
              	while (x <= 4)
        		{
                            System.out.println("Value of x:" + x);
  		            x++;
       		         }
          }
}
Output:
Value of x:1
Value of x:2
Value of x:3
Value of x:4
For loop:-
for loop provides a concise way of writing the loop structure. 
Unlike a while loop, a for statement consumes the initialization, condition and increment/decrement in one line thereby providing a shorter, easy to debug structure of looping.
Syntax:-
for (initialization condition; testing condition;increment/decrement)
    {
        statement(s);
   }
Flowchart:-




Example 1: This program will try to print “Hello World” 5 times.
// Java program to illustrate for loop 
class Demo 
{ 
        public static void main(String args[]) 
        { 
        
            for (int i = 1; i <= 5; i++) 
                {
                    System.out.println("Heelo World"); 
               }
        } 
} 

Output:
Hello World
Hello World
Hello World
Hello World
Hello World
Example 2
// Java program to illustrate for loop.
class Demo
{
        public static void main(String args[])
        {
       
       	         for (int x = 2; x <= 4; x++)
    {
            			System.out.println("Value of x:" + x);
    }
        }
}
Output:
Value of x:2
Value of x:3
Value of x:4
Do while:-
do while loop is similar to while loop with only difference that it checks for condition after executing the statements, and therefore is an example of Exit Control Loop.
Syntax:
do
{
    statements..
}
while (condition);
Flowchart:-
Example 1: 
This program will try to print “Hello World” 5 times.
class Demo 
{ 
        public static void main(String args[]) 
        { 
  
          int i = 1; 
            do
             { 
  
               System.out.println("Hello World"); 
                i++; 
              }  while (i < 6); 
          } 
} 
Output:
Hello World
Hello World
Hello World
Hello World
Hello World