What will be the output of the following program?

Question

import java.util.HashMap;
import java.util.Hashtable;
import java.util.Map;

public class Program {
public static void main(String... args) {
String k1 = "key1";

Map map = new Hashtable();

map.put(k1, "value1");
map.put(null, "value2");

System.out.println(map.get(k1));
System.out.println(map.get(null));
}
}

a. value1
value2
b. A NullPointer Exception will be thrown.
c. value1
value2
d. value1
null

Answer 1

a. value1
value2
HashMap allows null values as keys, so it will be matched and value2 will be displayed.