FIFO hashmap structure in Java.

fifo_hashmap.java

import java.util.*;
import java.lang.*;
import java.io.*;

public class FiFoHash {
  
    private static List<Integer> accessLevelIdList = new ArrayList<>();
    private static String employeeNumber = null;
    
    private static HashMap<Integer, String> PruneHashMap(HashMap<Integer, String> hm) {
        
      Set set = hm.entrySet();
      Iterator itr = set.iterator();
		
      String employeeId = null;
      List<Integer> idList = new ArrayList<>();
		
      while(itr.hasNext()) {
        
        Map.Entry mapEntry = (Map.Entry) itr.next();
      
        //System.out.print("Key: " + mapEntry.getKey());
        //System.out.println("  Value: " + mapEntry.getValue());
      
        if(employeeId == null) {
      	  employeeId = mapEntry.getValue().toString();
      	  idList.add((Integer) mapEntry.getKey());
      	  itr.remove();
      	  setEmployeeNumber(employeeId);
        }
      
        else {
        
      	  if(employeeId.equals(mapEntry.getValue())) {
      	    idList.add((Integer) mapEntry.getKey());
      	    itr.remove();
      	    setEmployeeNumber(employeeId);
      	  }
        }
      }
      
      setAccessLevelList(idList);
      
      return hm;
    }
    
    private static void setAccessLevelList(List<Integer> list) {
        accessLevelIdList = list;
    }
    
    private static void setEmployeeNumber(String employee) {
        employeeNumber = employee;
    }
    
    private static List<Integer> getAccessLevelList() {
        return accessLevelIdList;
    }
    
    private static String getEmployeeNumber() {
        return employeeNumber;
    }
    
    public static void main(String []args) {
      
      HashMap<Integer, String> hashMap = new HashMap();
      hashMap.put(45, "1111");
      hashMap.put(67, "1111");
      hashMap.put(545, "2222");
      hashMap.put(90, "1111");
      hashMap.put(195, "2222");
      hashMap.put(33, "3333");
    
      int originalSize = hashMap.size();
    
      HashMap<Integer, String> updatedHashMap = PruneHashMap(hashMap);
    
      while(updatedHashMap.size() > 0) 
        updatedHashMap = PruneHashMap(updatedHashMap);
    }
}