How to Retain the Insertion Order in a Set

Use LinkedHashSet to retain the insertion order

Set set = new LinkedHashSet();

// Add some elements
set.add("1");
set.add("2");
set.add("3");
set.add("1");

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