Map and Recursion Exercise

• Put 5 employees with their managers into a hashmap. (You can make up their names, but some managers should also be employees with managers of their own.)
• Print: "I am going to print the hashmap list"
• Print that map in the form : name is managed by mgr
• Copy the hashmap into a treemap
• Print "I am going to print the treemap list"
• Print that map and see it is sorted
• Ask the user which employee they would like to see all managers of.
• Create a recursive method printManagers which prints the line of managers above an employee. It takes in a String employee name and a Map of employees. It should print lines of employee is managed by mgr
  • public static void printManagers(String name , Map<String, String> m){
    • Questions to ask yourself before coding this recursion:
      • when will you stop getting another manager?
      • what will you do for each manager?
• Print: "I am going to print the managers now"
• Call the recursive printManagers method to print the managers

For an example, see this program that does something similar with friends mapped to phone numbers:

import java.util.HashMap;
import java.util.TreeMap;
import java.util.Map;
import java.util.LinkedList;
import java.util.Set;

public class Phone
{

public static void main (String[] args)
{
Map<String,String> phonelist = new HashMap<String,String>(); // create a hashmap
phonelist.put("Amy","235-125-2352"); // load values
phonelist.put("Jamie","235-255-2333");
phonelist.put("Carol","516-235-2332");
phonelist.put("Ted","235-125-2352");
System.out.println("print phone list from Hashmap");
for (String name : phonelist.keySet()){ // get a list of names from the map and iterate
System.out.println(name + " has phone number " + phonelist.get(name)); // get the phone number now that you have the value
}
Map<String,String> phonelistTree = new TreeMap<String,String>(phonelist); // create a treemap from the hashmap
System.out.println("print phone list from Treemap");
for (String name : phonelistTree.keySet()){ // get a list of names from the map and iterate
System.out.println(name + " has phone number " + phonelist.get(name)); // get the phone numbers from the map
}
Set<String> pkset = phonelistTree.keySet(); // get a list of names from the map
LinkedList<String> pk = new LinkedList<String>(pkset); // turn that set of names into a linked list
System.out.println("print phone list using recursion") ;
printPhoneList(pk, phonelistTree); // use recursion to print out the list - stop when the keyset is empty

}

public static void printPhoneList(LinkedList<String> phonekey , Map<String, String> m){

if (phonekey.size() == 0 ){
return;
}
else {
String name = phonekey.get(0);
phonekey.remove(0);
System.out.println(name + " has a phone number " + m.get(name));
printPhoneList(phonekey, m);
}
}

}