populating dictionary throws NullReferenceEexception

Question

I have a class with a string and dictionary properties:

public class Student
{
    public int StudentId { get; set; }
    public Dictionary<string, decimal> LevelGpa { get; set; }
}

Which I am trying to populate into a list of Students:

List<Student> students = new List<Student>()
{
    {new Student{StudentId = 1, LevelGpa = {{"Freshmen",3.1m}}}},
    {new Student{StudentId = 1, LevelGpa = {{"Sophomore",3.2m}}}},
    ...
};

But it is throwing a NullReferenceException at run time -

Object reference not set to an instance of an object.

What am I missing here?

Remove the semicolon from the end of `new List();` – Dour High Arch Mar 29 '17 at 22:06 — Dour High Arch, Mar 29 '17 at 22:06

score 1 · Accepted Answer · answered Mar 29 '17 at 21:59

You should create an instance of LevelGpa inside each instance of Student object:

List<Student> students = new List<Student>()
{
    {new Student() {
                    StudentId = 1, 
                    LevelGpa = new Dictionary<string, decimal>() {"Freshmen",3.1m} 
                   }
    },

    ...
};

populating dictionary throws NullReferenceEexception

1 Answers1