Question

I have two result sets (rs1 and rs2) having same fields. Now how to combine those two result sets into one so that duplicate rows are shown once.

Answer 1

if the two ResultSets are from the same database then why not combine them during the retrieval by using union; e.g.

select A, B
from C
union
select A, B
from D

However, if this is not an option then I suggest defining a Row class to represent a Row extracted from your ResultSet and implementing equals / hashCode to allow the Row to be compared for equality. Then simply add each Row to a Set (e.g. HashSet) in order to remove duplicates.