Java Certification Question 0081

How does the set collection deal with duplicate elements?

1) An exception is thrown if you attempt to add an element with a duplicate value
2) The add method returns false if you attempt to add an element with a duplicate value
3) A set may contain elements that return duplicate values from a call to the equals method
4) Duplicate values will cause an error at compile time

Answer)

2) The add method returns false if you attempt to add an element with a duplicate value

I find it a surprise that you do not get an exception.