java - How to loop this if statement? -

basically looking question asks. abookclass looks this:

import java.io.*; import java.util.*;  public class abook {    public static void main (string args[])    {        linkedlist addressbook = new linkedlist();        scanner input = new scanner(system.in);        system.out.println("would add friend? (say y or n)");         string reply = input.nextline();        if(reply.equals("y"))        {            system.out.println("what name of friend?");            string name = input.nextline();            system.out.println("what age of friend?");            int age = input.nextint();            friend newfriend = new friend(name,age);            addressbook.add("name: " + newfriend.name + "; " + "age: " + newfriend.age);            system.out.println("this address book far: " + addressbook);        }             else if(reply.equals("n")){            system.out.println("thank time");        }     } } 

and in case if need friend class use here, it:

public class friend {     public string name;     public int age;     public friend(string n, int a)     {            name = n;         age = a;     } } 

i unsure whether or not use "do" or "while" loop or how use it. awesome if explained why or how loop work on other.

thank you.

edit: did not realize how active community before posted question, , did not think many answers did in such short period of time. so, figured out own way loop before saw replies using do-while loop looked this.

import java.io.*;  import java.util.*;    public class abook {    public static void main(string args[]) {      linkedlist addressbook = new linkedlist();      scanner input = new scanner(system.in);      int n = 0;      {        system.out.println("would add friend? (say y or n)");        string reply = input.nextline();        if (reply.equals("y")) {          system.out.println("what name of friend?");          string name = input.nextline();          system.out.println("what age of friend?");          int age = input.nextint();          friend newfriend = new friend(name, age);          addressbook.add("name: " + newfriend.name + "; " + "age: " + newfriend.age);            system.out.println("this address book far: " + addressbook);          n++;        } else if (reply.equals("n")) {          system.out.println("thank time");          system.out.println("would know in address book? (say y or n)");          string userinput = input.nextline();          if (reply.equals("y")) {            system.out.println("this address book far: " + addressbook);            system.out.println("goodbye!");          } else if (reply.equals("n")) {            system.out.println("okay! goodbye!");          }          n = 101;        }      } while (n < 100);    }  }

it works well, , got fit if - else statement in this. trying sort linkedlist integer/age of "friend", can in order youngest oldest when print linkedlist. if point me in right direction, that'd awesome!

anyways, thank came me, , hope can others come across looking answers.

use do-while loop when want task @ least once no matter whether condition true or false. structure of do-while loop is-

do{    //do }while(condition);     

use while loop otherwise - if condition true loop executed. structure of while loop is-

while(condition){    //do }