Java tutorial
import java.util.Hashtable; import java.util.Set; public class Main { public static void main(String args[]) { // create hash table Hashtable<Integer, String> htable1 = new Hashtable<Integer, String>(); // put values in table htable1.put(1, "A"); htable1.put(2, "B"); htable1.put(3, "C"); htable1.put(4, "from java2s.com"); // create a set view Set st = htable1.keySet(); System.out.println("Display result: " + st); } }