We know that using Hashtable we can put and get the java objects relatively fast. But Hashtable does not maintain the order in which you add and retrieve the objects. Using a combination of hashtables we can accomplish this. With the following tip you can maintain the order.

  java.util.Hashtable hash = new java.util.Hashtable();for(int i = 0; i < 3 ; i++) {	Hashtable subHash = new Hashtable();String name = "name"+i;String value= "Foo"+i;	subHash.put(name, value);hash.put(new Integer(i), subHash);}

When you retrieve it, and if you want to retrieve the second item, which might be value associated with "name1" then you can have code:

 for(int i=0; i < hash.size(); i++){	Hashtable subHash = (Hashtable)hash.get(new Integer(i));	if(subHash != null){		String retValue =null;retValue = (String)subHash.get("name1")If(retValue != null)	return retValue;		}}

Also when we loop through the objects we can retrieve all the objects in the order in which they were inserted.