logo Practice-It logo

Main Page → Problems → Solve a Problem

retainAll

Language/Type: Java Sets and Maps
Author: Marty Stepp (on 2020/10/22)

Write a method called retainAll that takes two sets of integers as parameters and that removes any values in the first set that are not found in the second set. For example, given sets: 

s1: [0, 19, 8, 9, 12, 13, 14, 15]
s2: [0, 19, 2, 4, 5, 9, 10, 11]

If the following call is made: 

retainAll(s1, s2);

after the call, the sets would store the following values: 

s1: [0, 19, 9]
s2: [0, 19, 2, 4, 5, 9, 10, 11]

You are implementing a two-argument alternative to the standard Set method called retainAll, so you are not allowed to call that method to solve this problem. You are also not allowed to construct any structured objects to solve the problem (no set, list, stack, queue, string, etc) although you can construct iterators. Your method should not change the second set passed as a parameter.

Type your solution here:


This is a method problem. Write a Java method as described. Do not write a complete program or class; just the method(s) above.

You must log in before you can solve this problem.


Log In

If you do not understand how to solve a problem or why your solution doesn't work, please contact your TA or instructor.
If something seems wrong with the site (errors, slow performance, incorrect problems/tests, etc.), please

Is there a problem? Contact a site administrator.