How do you write a merge() method in java so you can merge two ordered
source arrays into an ordered destination array. For duplicate values,
only count once

You can use the TreeSet (java.util) to add these two ordered sequence
list into one.  Caveat, you have to use the Comparable interface
implemented for the objects that are part of your list.

Say you have class A is in the list.  Class A implements Comparable....

If you don't use the Comparable, TreeSet would do a natural sorting by
itself.  But it will keep only the unique object (even for this you
need to have the comparable implemented in your class).

Here is the link for you on Comparable
http://java.sun.com/j2se/1.4.2/docs/api/java/lang/Comparable.html