What is the output of the following Java program?

package test; import java.util.*; class Main { public static void main(String[] argh) { String key[] = { null, "B", null, "D", "E" }; Integer val[] = { 1, null, 3, 7, null }; Map hm = new HashMap(); for (int i = 0; i < key.length; i++) { hm.put(key[i], val[i]); } System.out.print(hm.toString()); } }