Question

Im working on a school assignment, and im supposed to make a array of hashmap like this:

HashMap<String, Person>[] mood = (HashMap<String, Person>[])  new HashMap<?, ?>[6];

im reading from a file, it goes something like this. the problem is that it gives NullPointerException where i try to put the mood into mood[0]! cant find anything about how the hashmap-array works in my books.. 🙁 would be happy for all help (:

Person p = new Person();
p.name = word[1];
p.age = word[2];
p.mood = word[3];

people.put(p.name, p);

 if (p.mood.equals("HAPPY")) {
 mood[0].put(p.mood, p); //NullPointerException 
 }

Answer 1

Basically, you did initialize an array of mood, but it’s initialized with nulls. So before you can call any method on mood[0] (or at any other indices), you need to put a non-null object inside mood[0].