import java.util.HashMap;
public class MyClass {
public static void main(String[] args) {
HashMap<Integer, String> hmap = new HashMap<Integer, String>();
hmap.put(1, "Darth Vader");
hmap.put(5, "Luke Skywalker");
hmap.put(7, "Obi-Wan Kenobi");
hmap.put(2, "Han Solo");
for (Integer i : hmap.keySet()) {
System.out.println(i);
}
}
}
/*
run:
1
2
5
7
*/