Question

Okay, I have a general idea of how to use the scanner, but i'm a bit confused of how to ask multiple questions and also how maps work, which is making me struggle on this questions... If i had more time, i'd study a bit more, but I only have about 3 hours. If possible, could you explain every step with comments?

Use the scanner class to ask users their name and age. Store at least 10 users on a map, and use the iterator to print all the values. Print the youngest user's name

Answer 1

/*******************************YoungestUser.java***********************/

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Scanner;
import java.util.Set;
import java.util.TreeMap;

public class YoungestUser {

   public static void main(String[] args) {

       Scanner scan = new Scanner(System.in);// initialize the scanner

       Map<Integer, String> users = new HashMap<>();// initialize map

       /*
       * for loop to enter number of times you want to enter user
       */
       for (int i = 0; i < 3; i++) {

           System.out.print("Enter the name of user: ");// prompt for name
           String name = scan.nextLine();// read name as full line
           System.out.print("Enter the age of user: ");// prompt for age
           int age = scan.nextInt();// read age
           scan.nextLine();// clear the buffer after read nextInt
           users.put(age, name);// put data in map
       }

       Map<Integer, String> treeMap = new TreeMap<Integer, String>(users);//sort the map using age as key
       System.out.println("****************Print the users youngest to oldest********");
       Set<Entry<Integer, String>> entrySet = treeMap.entrySet();
       Iterator<Entry<Integer, String>> it = entrySet.iterator(); // using iterator iterate the entry set
       while (it.hasNext()) {
           Map.Entry<Integer,String> me = (Map.Entry<Integer,String>) it.next();// read value one by one
           System.out.println("Name is: " + me.getValue() + " and age is: " + me.getKey());// print the data
       }
      
       Entry<Integer, String> entry = treeMap.entrySet().iterator().next();
       System.out.println("The youngest users is: "+entry.getValue());
       scan.close();// close the scanner
   }
}
/****************output*****************/

Enter the name of user: JKS
Enter the age of user: 10
Enter the name of user: Virat
Enter the age of user: 56
Enter the name of user: Gagan
Enter the age of user: 6
****************Print the users youngest to oldest********
Name is: Gagan and age is: 6
Name is: JKS and age is: 10
Name is: Virat and age is: 56
The youngest users is: Gagan

Please let me know if you have any doubt or modify the answer, Thanks:)