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For this question assume the following implementation of LinkedList and Node:
public class LinkedList<T> implements ListInterface...
X394: LinkedListInsertionSortSplitInTwo
For this question assume the following implementation of LinkedList and Node:
public class LinkedList<T> implements ListInterface<T> {
private Node<T> firstNode;
// the size of the linked list
private int size;
/**
* Creates a new LinkedList object
*/
public LinkedList() {
firstNode = null;
size = 0;
}
/**
* Gets head of list
*
* @return head of linked list
*/
public Node<T> getFirstNode() {
return firstNode;
}
/**
* Gets the number of elements in the list
*
* @return the number of elements
*/
@Override
public int getLength() {
return size;
}
/**
* Ensures indices that are within the appropriate bounds
*
* @throws IndexOutOfBoundsException
* if either newPosition less than 0 or newPosition greater
* than
* getLength() + 1.
*/
public void indexInBounds(int index) {
if (index < 0 || index > getLength()) {
throw new IndexOutOfBoundsException("Index " + index
+ " out of bounds");
}
}
/**
* Adds the object to the position in the list
*
* @precondition obj cannot be null
* @param index
* where to add the object
* @param obj
* the object to add
* @throws IndexOutOfBoundsException
* if index is less than zero or greater than size
* @throws IllegalArgumentException
* if obj is null
*/
@Override
public void add(int index, T obj) {
// check if the object is null
if (obj == null) {
throw new IllegalArgumentException("Object is null");
}
// check if the index is out of bounds
indexInBounds(index);
Node<T> current = firstNode;
// empty stack case
if (isEmpty() || index == 0) {
Node<T> newNode = new Node<T>(obj);
newNode.setNext(firstNode);
firstNode = newNode;
}
// all other cases
else {
int currentIndex = 0;
while (current != null) {
if ((currentIndex + 1) == index) {
Node<T> nextNext = current.next;
Node<T> newNode = new Node<T>(obj);
current.setNext(newNode);
newNode.setNext(nextNext);
}
current = current.next();
currentIndex++;
}
}
size++;
}
/**
* Adds the object to the end of the list.
*
* @precondition obj cannot be null
* @param obj
* the object to add
* @throws IllegalArgumentException
* if obj is null
*/
@Override
public void add(T obj) {
// check if the object is null
if (obj == null) {
throw new IllegalArgumentException("Object is null");
}
Node<T> current = firstNode;
// empty stack case
if (isEmpty()) {
firstNode = new Node<T>(obj);
}
// other cases
else {
while (current.next != null) {
current = current.next;
}
current.setNext(new Node<T>(obj));
}
size++;
}
/**
* Checks if the array is empty
*
* @return true if the array is empty
*/
@Override
public boolean isEmpty() {
return (size == 0);
}
/**
* Removes the first instance of the given object from the list
*
* @param obj
* the object to remove
* @return true if successful
*/
@Override
public boolean remove(T obj) {
Node<T> current = firstNode;
// account for matching firstNode
if ((null != firstNode) && (obj.equals(current.data))) {
firstNode = firstNode.next;
size--;
return true;
}
// account for 2+ size
while (getLength() >= 2 && (current.next != null)) {
if ((obj.equals(current.next.data))) {
current.setNext(current.next.next);
size--;
return true;
}
current = current.next;
}
// this accounts for the isEmpty case or the object does not exist
return false;
}
/**
* Removes the object at the given position
*
* @param index
* the position of the object
* @return true if the removal was successful
* @throws IndexOutOfBoundsException
* if there is not an element at the index
*/
@Override
public boolean remove(int index) {
// if the index is invalid
indexInBounds(index);
Node<T> current = firstNode;
if (index == 0) {
firstNode = firstNode.next;
size--;
return true;
}
int currentIndex = 0;
while (current.next != null) {
if ((currentIndex + 1) == index) {
Node<T> newNext = current.next.next;
current.setNext(newNext);
size--;
return true;
}
current = current.next;
currentIndex++;
}
// if the element was never found, this also handles empty case
throw new IndexOutOfBoundsException("Index " + index
+ " out of bounds");
}
/**
* Gets the object at the given position
*
* @param index
* where the object is located
* @return The object at the given position
* @throws IndexOutOfBoundsException
* if no node at the given index
*/
@Override
public T getEntry(int index) {
indexInBounds(index);
Node<T> current = firstNode;
int currentIndex = 0;
while (current != null) {
if (currentIndex == index) {
return current.data;
}
currentIndex++;
current = current.next;
}
// If we get here then the index is out of bounds
throw new IndexOutOfBoundsException("Index " + index
+ " out of bounds");
}
/**
* Checks if the list contains the given object
*
* @param obj
* the object to check for
* @return true if it contains the object
*/
@Override
public boolean contains(T obj) {
Node<T> current = firstNode;
while (current != null) {
if (obj.equals(current.data)) {
return true;
}
current = current.next;
}
return false;
}
/**
* Removes all of the elements from the list
*/
@Override
public void clear() {
// make sure we don't call clear on an empty list
if (firstNode != null) {
firstNode.setNext(null);
firstNode = null;
size = 0;
}
}
/**
* Gets the last time the given object is in the list
*
* @param obj
* the object to look for
* @return the last position of it. -1 If it is not in the list
*/
@Override
public int lastIndexOf(T obj) {
int lastIndex = -1;
Node<T> current = firstNode;
int currentIndex = 0;
while (current != null) {
if (obj.equals(current.data)) {
lastIndex = currentIndex;
}
currentIndex++;
current = current.next;
}
return lastIndex;
}
/**
* Returns a string representation of the list If a list contains A, B,
* and
* C, the following should be returned "{A, B, C}" (Without the
* quotations)
*
* @return a string representing the list
*/
@Override
public String toString() {
String result = "{";
Node<T> current = firstNode;
while (current != null) {
result += "" + current.data;
current = current.next;
if (current != null) {
result += ", ";
}
}
result += "}";
return result;
}
/**
* Returns an array representation of the list If a list contains A, B,
* and
* C, the following should be returned {A, B, C}, If a list
* contains A, B, C, and C the following should be returned {A, B, C, C}
*
* @return an array representing the list
*/
public Object[] toArray() {
Object[] array = new Object[this.getLength()];
Node<T> current = firstNode;
int count = 0;
while (current != null) {
array[count] = current.getData();
current = current.next;
count++;
}
return array;
}
/**
* Returns true if both lists have the exact same contents
* in the exact same order
*
* @return a boolean of whether two lists have the same contents,
* item per item and in the same order
*/
@SuppressWarnings("unchecked")
@Override
public boolean equals(Object obj) {
if (obj == this) {
return true;
}
if (obj == null) {
return false;
}
if (this.getClass() == obj.getClass()) {
LinkedList<T> other = ((LinkedList<T>)obj);
if (other.getLength() == this.getLength()) {
Node<T> current = firstNode;
Node<T> otherCurrent = other.firstNode;
while (current != null) {
if (!current.getData().equals(otherCurrent.getData())) {
return false;
}
current = current.next();
otherCurrent = otherCurrent.next();
}
return true;
}
}
return false;
} // end equals
/**
* replaces item at givenPosition with data represented by newEntry
*
* @param givenPosition
* index in Linked List to replace
* @param newEntry
* new value to put in at givenPosition
* @return data that was overwritten
*
* @throws IndexOutOfBoundsException
* if index out of bounds
*/
@Override
public T replace(int givenPosition, T newEntry) {
indexInBounds(givenPosition);
T oldData;
if (givenPosition == 0) {
oldData = firstNode.getData();
firstNode.setData(newEntry);
return oldData;
}
else {
Node<T> current = firstNode;
int currentIndex = 0;
while (current != null) {
if (currentIndex == givenPosition) {
oldData = firstNode.getData();
current.setData(newEntry);
return oldData;
}
current = current.next();
currentIndex++;
}
}
// if the element was never found, this also handles empty case
throw new IndexOutOfBoundsException("Index " + givenPosition
+ " out of bounds");
}// end Replace
} // end LinkedChain
/**
* This represents a node in a singly linked list. This node stores data
* along with having a pointer to the next node in the list
*
* @param <D>
* This is the type of object that this class will store
*/
public static final class Node<D> {
// The data element stored in the node.
private D data;
// The next node in the sequence.
private Node<D> next;
/**
* Creates a new node with the given data
*
* @param d
* the data to put inside the node
*/
public Node(D d) {
this(d, null);
}
public Node(D d, Node<D> n) {
data = d;
next = n;
}
/**
* Sets the node after this node
*
* @param n
* the node after this one
*/
public void setNext(Node<D> n) {
next = n;
}
/**
* Gets the next node
*
* @return the next node
*/
public Node<D> next() {
return next;
}
/**
* Gets the data in the node
*
* @return the data in the node
*/
public D getData() {
return data;
}
public void setData(D newData) {
data = newData;
}
} // End Node
For this question we won't be directly working within LinkedList however. Instead, we'll be working with a Runner class:
public class Runner<T> {
private LinkedList<T> firstItemList;
private LinkedList<T> listRemainder;
public Runner() {
firstItemList = null;
listRemainder = null;
}
}
For this question, write a method for the Runner class that will take in a LinkedList, split into two linked lists, and assign their values to firstItemList and listRemainder. Assign firstItemList to be a new LinkedList that just contains the first value. Assign listRemainder to be a new linkedList that contains everything EXCEPT the remainder.
More clearly,
if you are given a linked list that looks like: 1 --> 2 --> 3 --> 4
Then assign firstItemList to 1 --> null
and listRemainder to `2 --> 3 --> 4``
Please note this will be the only question that deals with a Runner Class instead of the LinkedList class directly.
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