This is a partial implementation of class TheList in Java. TheList object is a singly-linked list. Where the first node is referenced by the var head, and the last node is referenced by the var tail.

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class ListNode{

public ListNode(E data, ListNode next){

this.data = data;

this.next = next;

}

public E data;

public ListNode next;

}

class TheList implements List{

...

private ListNode head, tail;

}

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Implement this function in Java in the class TheList:

hashCode(): this function returns the hash code of the list. Let size be n, and hashCode(e_i) be the hash code of the ith element (i = 0, 1, ... , n-1).

Then the hash code of this list is ?ⁿ_i ( i +1) X hashCode(e_i). It is assumed that the element type E provides a function called hashCode.