How to use the do-while loop statement in java program?

[KALIDA]

Hi friends,
I am second year Computer Science student. I recently started learning java language. In our last lecture we learn do-while loop statement. But still I don't understand how to use this in java program. Can anyone tell me how to use the do-while loop statement in java program? Please help me.
Thank you.

[absolute55]

Hey it is very easy process to use do- while loop in the Java programming language. Rather than evaluating the expression at the beginning like we do in while loop, the do-while loop evaluates its expression at the end of the loop. Because of this the loop executes at least once during the program execution even if it is wrong at first time.

package org.kodejava.example.lang;

public class DoWhileEg {
    public static void main(String[] args) {
        int k = 0;

       
        do {
            
            System.out.println(i);
            k++;
        } while (k <= 6);
    }
}

[Reegan]

If you know how to use while statement then it will easy for you you to understand how to use the do-while loop statement in java program. The main difference between do-while statement and while statement is that do-while statement evaluates its expression at the bottom of the loop instead of the top. For this reason the statements within the do block are always executed at least once thorugh out the execution.

class DoWhileDemo {
     public static void main(String[] args){
          int counts = 1;
          do {
               System.out.println("Count is: " + counts);
               counts++;
          } while (counts <= 11);
     }
}

Output will be as follows :
1
2
3
4
5
6
7
8
9
10
11

[opaper]

There are some situation where you have to run some statements and processes once at least. In this case you have to use the do while loop to solve such type of problem. Do - while loop executes all the statements first at once and then check the condition.

The Syntax for the do-while loop is as follows:

do
{
statements;
}
while(condition);

public class DoWhile{
  public static void main(String[] args){
    int j = 12345;
    int k,w = 0;
    System.out.println("The original number : " + j);
    do{
      k = j % 10;
      w = w * 10 +k;
      j = j / 10;
    }while (j > 0);
    System.out.println("The reverse number : " +w);
  }
}

[MindSpace]

In the do-while syntax code block will always be run at least once. It is very useful when you want to execute at least first statement of particular code.
Syntax of Do while statement is as follows.

do {
code_block;
} while (condition);

If you don't understand how to use do-while statement then try to understand following example.

// This is the Hello program in Java
 
 class Hello {
 
   public static void main (String args[]) {
 
     int k = -1;
     do {
       if (k == -1) System.out.print("Hello to all "); 
       else {
         System.out.print(args[k]);  
         System.out.print(" ");
       }
       k = k + 1;
     } while (k < args.length);
     System.out.println(); 
  }
 
}

[Modifier]

Do while statement is used in java program when you want to run program in loop on pre defined condition. Do while statement helps to run any java statement in block to execute on first block without checking conditions. In do while statement we have to use "do" key word in top and "while" keyword in last to make block. Try to understand following example.

public class JavaDoWhileStatementExample {

    public static void main(String[] args) {

        int k=0;
        
        do
        {
            System.out.println("do while loop iterator1 :"+k);
            k++;
        }
        while(k<0);

        int l=0;
       
        do
        {
            System.out.println("do while loop iterator2 :"+l);
            l++;
        }
        while(l<5);
    }
}