For a Generic outerclass, why do i need to declare the nested class static?

Question

I am trying to write the Data Structure for a Hash Table using Chaining. When i remove the keyword "static" from the nested class, i get the error that "Cannot create a generic array of SeparateChaining.Node"? on the line where i allocate memory to hmap using new.

With the static keyword it works fine.Can anybody please point out the significance of the keyword static here and the difference it makes? I am creating an array of object, then how come it shows generic array in the error (Eclipse)?

public class SeparateChaining<Key,Value> {

    private int m;

    private Node[] hmap;

    private int n;

    public SeparateChaining()
    {
        m=5;
        n=0;

        //error here on removal of static keyword from the node  class declaration
                hmap=new Node[m];

    }

    private ____ class Node //works fine with static. Otherwise shows error
    {
        private Object key;
        private Object value;
        private Node next;

        public Node(Object k, Object v)
        {

            key=k;
            value=v;
        }

    }

Thanks

Answer 1

If you declare the inner Node class as static, then the class is associated with the outer class SeparateChaining. Node is then in fact SeparateChaining.Node.

Without the static, it will be associated with an instance of SeparateChaining, which will need a couple type parameters, thus the inner Node class will also need those type parameters. Node is then in fact SeparateChaining<Key, Value>.Node; and in Java, creating an array of generics is not legal.