LinkedHashSet - Creating a Set That Retains Order-of-Insertion

To retain the order of insertion, LinkedHashSet is used.

Example:

Set set = new LinkedHashSet(); 
// Add some elements 
set.add("1"); set.add("2"); set.add("3"); set.add("2"); 

// List the elements 
for (Iterator it=set.iterator(); it.hasNext(); ) 
{ 
    Object o = it.next(); 
} // [1, 2, 3]