Change this code to make a process control block linked list.:

/* * Java Program to Implement Singly Linked List */ import java.util.Scanner; /* Class Node */ class Node { protected int data; protected Node link; /* Constructor */ public Node() { link = null; data = 0; } /* Constructor */ public Node(int d,Node n) { data = d; link = n; } /* Function to set link to next Node */ public void setLink(Node n) { link = n; } /* Function to set data to current Node */ public void setData(int d) { data = d; } /* Function to get link to next node */ public Node getLink() { return link; } /* Function to get data from current Node */ public int getData() { return data; } } /* Class linkedList */ class linkedList { protected Node start; protected Node end ; public int size ; /* Constructor */ public linkedList() { start = null; end = null; size = 0; } /* Function to check if list is empty */ public boolean isEmpty() { return start == null; } /* Function to get size of list */ public int getSize() { return size; } /* Function to insert an element at begining */ public void insertAtStart(int val) { Node nptr = new Node(val, null); size++ ; if(start == null) { start = nptr; end = start; } else { nptr.setLink(start); start = nptr; } } /* Function to insert an element at end */ public void insertAtEnd(int val) { Node nptr = new Node(val,null); size++ ; if(start == null) { start = nptr; end = start; } else { end.setLink(nptr); end = nptr; } } /* Function to insert an element at position */ public void insertAtPos(int val , int pos) { Node nptr = new Node(val, null); Node ptr = start; pos = pos - 1 ; for (int i = 1; i < size; i++) { if (i == pos) { Node tmp = ptr.getLink() ; ptr.setLink(nptr); nptr.setLink(tmp); break; } ptr = ptr.getLink(); } size++ ; } /* Function to delete an element at position */ public void deleteAtPos(int pos) { if (pos == 1) { start = start.getLink(); size--; return ; } if (pos == size) { Node s = start; Node t = start; while (s != end) { t = s; s = s.getLink(); } end = t; end.setLink(null); size --; return; } Node ptr = start; pos = pos - 1 ; for (int i = 1; i < size - 1; i++) { if (i == pos) { Node tmp = ptr.getLink(); tmp = tmp.getLink(); ptr.setLink(tmp); break; } ptr = ptr.getLink(); } size-- ; } /* Function to display elements */ public void display() { System.out.print(" Singly Linked List = "); if (size == 0) { System.out.print("empty "); return; } if (start.getLink() == null) { System.out.println(start.getData() ); return; } Node ptr = start; System.out.print(start.getData()+ "->"); ptr = start.getLink(); while (ptr.getLink() != null) { System.out.print(ptr.getData()+ "->"); ptr = ptr.getLink(); } System.out.print(ptr.getData()+ " "); } } /* Class SinglyLinkedList */ public class SinglyLinkedList { public static void main(String[] args) { Scanner scan = new Scanner(System.in); /* Creating object of class linkedList */ linkedList list = new linkedList(); System.out.println("Singly Linked List Test "); char ch; /* Perform list operations */ do { System.out.println(" Singly Linked List Operations "); System.out.println("1. insert at begining"); System.out.println("2. insert at end"); System.out.println("3. insert at position"); System.out.println("4. delete at position"); System.out.println("5. check empty"); System.out.println("6. get size"); int choice = scan.nextInt(); switch (choice) { case 1 : System.out.println("Enter integer element to insert"); list.insertAtStart( scan.nextInt() ); break; case 2 : System.out.println("Enter integer element to insert"); list.insertAtEnd( scan.nextInt() ); break; case 3 : System.out.println("Enter integer element to insert"); int num = scan.nextInt() ; System.out.println("Enter position"); int pos = scan.nextInt() ; if (pos <= 1 || pos > list.getSize() ) System.out.println("Invalid position "); else list.insertAtPos(num, pos); break; case 4 : System.out.println("Enter position"); int p = scan.nextInt() ; if (p < 1 || p > list.getSize() ) System.out.println("Invalid position "); else list.deleteAtPos(p); break; case 5 : System.out.println("Empty status = "+ list.isEmpty()); break; case 6 : System.out.println("Size = "+ list.getSize() +" "); break; default : System.out.println("Wrong Entry "); break; } /* Display List */ list.display(); System.out.println(" Do you want to continue (Type y or n) "); ch = scan.next().charAt(0); } while (ch == 'Y'|| ch == 'y'); } }