Question

Write a java program that stores the following information in a HashMap:

Sue is friends with Bob, Jose, Alex, and Cathy

Cathy is friends with Bob and Alex

Bob is friends with Alex, Jose, and Jerry

After storing the information, prompt the user to enter a name. If the name that is entered is Sue, Cathy, or Bob, print out the name and the list of friends. Otherwise print a message indicating that the name is not in the HashMap.

Answer 1

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Scanner;

public class FriendsList {
   public static void main(String[] args) {
       HashMap<String, List<String>> list = new HashMap<String, List<String>>();
       List<String> frnds = new ArrayList<String>();
       frnds.add("Bob");
       frnds.add("Jose");
       frnds.add("Alex");
       frnds.add("Cathy");
       list.put("Sue", frnds);

       frnds = new ArrayList<String>();
       frnds.add("Bob");
       frnds.add("Alex");
       list.put("Cathy", frnds);

       frnds = new ArrayList<String>();
       frnds.add("Jose");
       frnds.add("Alex");
       frnds.add("Cathy");
       frnds.add("Jerry");
       list.put("Bob", frnds);
       Scanner sc = new Scanner(System.in);
       System.out.println("Enter the name: ");
       String name = sc.nextLine();
       sc.close();
       frnds = list.get(name);
       if (frnds == null)
           System.out.println(name + " does not exist in the list");
       else
           System.out.println(frnds);

   }
}