import java.util.*;

public class StudentMap {
  
  public static void printMapEntries(Map<Integer,Student> map) { 
    Set<Map.Entry<Integer,Student>> set = map.entrySet();
    Iterator<Map.Entry<Integer,Student>> it = set.iterator();
    while(it.hasNext()) {
      Map.Entry<Integer,Student> entry = it.next();
      System.out.println(entry.getKey() + " -> "+ entry.getValue() );
    }
  }
  
  public static void printMapValues(Map<Integer,Student> map) { 
    Collection<Student> coll = map.values();
    Iterator<Student> it = coll.iterator();
    while(it.hasNext()) {
      System.out.println(it.next().toString());
    }
  }
  
  public static void printMapKeys(Map<Integer,Student> map) { 
    Set<Integer> set = map.keySet();
    Iterator<Integer> it = set.iterator();
    while(it.hasNext()) {
      System.out.println(it.next().toString());
    }
  }
  
  public static void main(String args[]) {
    Map<Integer,Student> students = new HashMap<>();
    students.put(1, new Student("John", "Smith"));
    students.put(2, new Student("Stanley", "Peters"));
    students.put(3, new Student("Edgar", "Bloch"));
    students.put(4, new Student("Suzan", "Miles"));
    students.put(5, new Student("Mary", "Poppins"));
    
    
    System.out.println("\nMap keys are:");
    printMapKeys(students);
    System.out.println("\nMap values are:");
    printMapValues(students);
    System.out.println("\nMap key-value pairs are:");
    printMapEntries(students);
  }
}