can't explain NullPointerException

Question

In the following code, i have a method to get a Vector of persons with the same zodiac sign. persoane is a Vector<Persoana>. I keep getting a NullPointerException at the if condition (persoane is definetly not null). I am unable to see why. Any help would be greatly appreciated

public Vector<Persoana> cautaDupaZodie(String zodie)
{
    Vector<Persoana> rezultat= new Vector<Persoana>();

    for(int i=0; i<persoane.size(); i++)
    {
        if(persoane.get(i).getData().getZodie().equals(zodie)) //the exception occurs here
        {
            rezultat.add(persoane.get(i));
        }

    }

    return rezultat;
}

Answer 1

NullPointerException occurs, when you try to call a method on an Object that is null.

This means that one of the following returns null:

• get(i)
• getData()
• getZodie()

Add them one by one to find out what actually is causing your exception.