public class Test 
{
    private static final Map<Integer, String> MY_MAP = createMap();

    private static Map<Integer, String> createMap() {
        Map<Integer, String> result = new HashMap<Integer, String>();
        result.put(1, "one");
        result.put(2, "two");
        return Collections.unmodifiableMap(result);
    }
}

To find the next key while using HashMap with Integer as Key the following function can be used.

  1. Iterate through List of Keys
  2. Sort the Keys
  3. Find the Highest value by looking into Key at size-1
  4. The next key to be used is received by adding 1 to Key(lastMaxElem) at size-1
private Integer getNextKey()
{
    List<Integer> keyList = new ArrayList<Integer>();
    int lastMaxElem = 0;
		
    HashMap WaterfallHM = (HashMap) getFromWorkFlowScope("WaterfallHM");		
    Set<Integer> keys = WaterfallHM.keySet();
        
    for ( Integer key : keys) {
	keyList.add(key);
    }
		
    Collections.sort(keyList); // Sort the arraylist
    lastMaxElem = keyList.get(keyList.size() - 1);
    lastMaxElem++; 
		
    return new Integer(lastMaxElem);
}
public static void printMap(Map mp) 
{
    Iterator it = mp.entrySet().iterator();

    while (it.hasNext()) 
    {
        Map.Entry pairs = (Map.Entry)it.next();
        System.out.println(pairs.getKey() + " = " + pairs.getValue());

        //Avoids a ConcurrentModificationException
        it.remove(); 
    }
}