Please help with this Java/database question!

package datastructure; public class UseMap { public static void main(String[] args) { /* * Demonstrate how to use Map that includes storing and retrieving elements. * Add List into a Map. Like, Map> list = new HashMap>(); * Use For Each loop and while loop with Iterator to retrieve data. a * * Use any databases[MongoDB, Oracle, MySql] to store data and retrieve data. */ } }