usage of Map.Entry interface in java collections

Hi,

    
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

public class Main {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
// TODO code application logic here
// Create a hash map
        HashMap hm = new HashMap();
// Put elements to the map
        hm.put("John Doe", new Double(3434.34));
        hm.put("Tom Smith", new Double(123.22));
        hm.put("Jane Baker", new Double(1378.00));
        hm.put("Todd Hall", new Double(99.22));
        hm.put("Ralph Smith", new Double(-19.08));
// Get a set of the entries
        Set set = hm.entrySet();
// Get an iterator
        Iterator i = set.iterator();
// Display elements
        while (i.hasNext()) {
            Map.Entry me = (Map.Entry) i.next();
            System.out.print(me.getKey() + ": ");
            System.out.println(me.getValue());
        }
        System.out.println();
// Deposit 1000 into John Doe's account
        double balance = ((Double) hm.get("John Doe")).doubleValue();
        hm.put("John Doe", new Double(balance + 1000));
        System.out.println("John Doe's new balance: "
                + hm.get("John Doe"));
    }
}