DLList

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help me write the java program

Answer

Hello,You can see the .java files in the zip. I hope I was helpful with your assignment. Also, I would be happy to help you with your other programming, mathematics or statistics assignment, you can message to me. (Please message me if you want comments, so I can re-upload the commented version)Have a nice dayKerem

Answer

Please find attachment. Read this well and use it to enhance as well as develop your understanding and knowledge about the given assignment. If you have any queries feel free to send me a message. Thank you very much!Kindly leave healthy feedback with 5stars as this is my real reward of all hard working. BEST OF LUCK :) regards,Dr. Charles Kennedy (expertsolution)Complete Program: File: DLList.java // DLList class implementation import java.util.Iterator; public class DLList implements Iterable { private static class Node { public Node prev, next; public T data; public Node(Node prev, T data, Node next) { this.prev = prev; this.next = next; this.data = data; } } private Node head, tail; private int numberOfElements; // newly added variable // Conductor inner class private static class Conductor implements Iterator { public Node car; public Conductor(DLList list) { car = list.head; } public boolean hasNext() { return car != null; } public T next() { T data = car.data; car = car.next; return data; } } // end of Conductor inner class // default constructor implementation [ MODIFIED ] public DLList() { head = tail = null; numberOfElements = 0; // newly added statement } // add method implementation [ MODIFIED ] public void add(T data) { if (tail == null) { head = new Node(null, data, null); tail = head; } else { tail.next = new Node(tail, data, null); tail = tail.next; } numberOfElements++; // newly added statement } // get method implementation [ MODIFIED ] public T get(int i) { if (i < 0 || i >= numberOfElements) throw new IndexOutOfBoundsException(); if(i < numberOfElements / 2) { // start from the head node Node current = head; for (int j = 0; current != null && j < i; j++) { current = current.next; } return current.data; } else { // start from the tail node Node current = tail; for (int j = numberOfElements - 1; current != null && j > i; j--) { current = current.prev; } return current.data; } } // remove method implementation [ MODIFIED ] public T remove(int i) { if (i < 0) throw new IndexOutOfBoundsException(); Node current = head; for (int j = 0; current != null && j < i; j++) { current = current.next; } if (current == null) throw new IndexOutOfBoundsException(); if (current.prev != null) current.prev.next = current.next; else head = head.next; if (current.next != null) current.next.prev = current.prev; else tail = tail.prev; numberOfElements--; // newly added statement return current.data; } // iterator method implementation public Iterator iterator() { return new Conductor(this); } // BackwardConductor inner class implementation [ NEWLY ADDED] private static class BackwardConductor implements Iterator { public Node car; // Next node to visit public BackwardConductor(DLList list) { car = list.tail; // Begin at tail } public boolean hasNext() { return car != null; // No more to visit } public T next() { T data = car.data; // Remember current car = car.prev; // Advance to previous car return data; // Return old car data } } // descendingIterator method implementation [ NEWLY ADDED] public Iterator descendingIterator() { return new BackwardConductor(this); } // size method implementation [ NEWLY ADDED] public int size() { return numberOfElements; } // reverse method implementation [ NEWLY ADDED] public void reverse() { Node temp1; Node temp2; temp1 = head; if (temp1 != null) { head = tail; tail = temp1; temp1 = head; while (temp1 != tail) { temp2 = temp1.next; temp1.next = temp1.prev; temp1.prev = temp2; temp1 = temp1.next; } temp2 = temp1.next; temp1.next = temp1.prev; temp1.prev = temp2; } } // improved add method implementation [ NEWLY ADDED] public boolean add(int i, T s) { if (i < 0 || i >= numberOfElements) return false; Node newNode = new Node(null, s, null); if(numberOfElements == 0) { head = newNode; tail = head; } else if(i == 0) { newNode.next = head; head.prev = newNode; head = newNode; } else if(i == numberOfElements) { tail.next = newNode; newNode.prev = tail; tail = newNode; } else { Node current = null; if(i < numberOfElements / 2) { current = head; for (int j = 0; current != null && j < i; j++) { current = current.next; } } else { current = tail; for (int j = numberOfElements - 1; current != null && j > i; j--) { current = current.prev; } } Node temp = current.prev; temp.next = newNode; newNode.prev = temp; newNode.next = current; current.prev = newNode; } numberOfElements++; return true; } } // end of DLList class File: DLListTest.java // DLListTest class implementation import java.util.Iterator; public class DLListTest { public static void main(String[] args) { DLList list = new DLList(); list.add(11); list.add(22); list.add(33); list.add(44); list.add(55); list.add(66); list.add(77); list.add(88); System.out.println("The descendingIterator() tesing... "); Iterator itr = list.descendingIterator(); while(itr.hasNext()) { System.out.print(itr.next() + " "); } System.out.println(" The size() testing..."); System.out.println("Number of elements in the list: " + list.size()); System.out.println(" Improved get() testing..."); for(int i = 0; i < list.size(); i++) { System.out.println("Element at " + i + ": " + list.get(i)); } System.out.println(" The reverse() is calling..."); list.reverse(); System.out.println(" Improved get() testing again..."); for(int i = 0; i < list.size(); i++) { System.out.println("Element at " + i + ": " + list.get(i)); } System.out.println(" Adding elements with indices using improved add()..."); list.add(0, 100); list.add(3, 133); list.add(7, 177); System.out.println(" Improved get() testing again..."); for(int i = 0; i < list.size(); i++) { System.out.println("Element at " + i + ": " + list.get(i)); } } } // end of DLListTest class Sample Output:

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