/**

LinkedBag.java

*/

public final class LinkedBag implements BagInterface

{

private Node firstNode; // Reference to first node

private int numberOfEntries;

public LinkedBag()

{

firstNode = null;

numberOfEntries = 0;

} // end default constructor

/** Sees whether this bag is empty.

@return True if this bag is empty, or false if not. */

public boolean isEmpty()

{

return numberOfEntries == 0;

} // end isEmpty

/** Gets the number of entries currently in this bag.

@return The integer number of entries currently in this bag. */

public int getCurrentSize()

{

return numberOfEntries;

} // end getCurrentSize

/** Adds a new entry to this bag.

@param newEntry The object to be added as a new entry

@return True if the addition is successful, or false if not. */

public boolean add(T newEntry) // OutOfMemoryError possible

{

// Add to beginning of chain:

Node newNode = new Node(newEntry);

newNode.next = firstNode; // Make new node reference rest of chain

// (firstNode is null if chain is empty)

firstNode = newNode; // New node is at beginning of chain

numberOfEntries++;

return true;

} // end add

/** Retrieves all entries that are in this bag.

@return A newly allocated array of all the entries in this bag. */

public T[] toArray()

{

// The cast is safe because the new array contains null entries

@SuppressWarnings("unchecked")

T[] result = (T[])new Object[numberOfEntries]; // Unchecked cast

int index = 0;

Node currentNode = firstNode;

while ((index

{

result[index] = currentNode.data;

index++;

currentNode = currentNode.next;

} // end while

return result;

} // end toArray

/** Produces a string equivalent of the linked list.

@return A newly allocated String of all the entries in this bag. */

public String toString()

{

String x = " ";

Node currentNode = firstNode;

while ( currentNode != null )

{

x = x + currentNode.data + " ";

currentNode = currentNode.next;

} // end while

return x;

} // end toArray

/** Counts the number of times a given entry appears in this bag.

@param anEntry The entry to be counted.

@return The number of times anEntry appears in this bag. */

public int getFrequencyOf(T anEntry)

{

int frequency = 0;

int counter = 0;

Node currentNode = firstNode;

while ((counter

{

if (anEntry.equals(currentNode.data))

{

frequency++;

} // end if

counter++;

currentNode = currentNode.next;

} // end while

return frequency;

} // end getFrequencyOf

/** Tests whether this bag contains a given entry.

@param anEntry The entry to locate.

@return True if the bag contains anEntry, or false otherwise. */

public boolean contains(T anEntry)

{

boolean found = false;

Node currentNode = firstNode;

while (!found && (currentNode != null))

{

if (anEntry.equals(currentNode.data))

found = true;

else

currentNode = currentNode.next;

} // end while

return found;

} // end contains

// Locates a given entry within this bag.

// Returns a reference to the node containing the entry, if located,

// or null otherwise.

private Node getReferenceTo(T anEntry)

{

boolean found = false;

Node currentNode = firstNode;

while (!found && (currentNode != null))

{

if (anEntry.equals(currentNode.data))

found = true;

else

currentNode = currentNode.next;

} // end while

return currentNode;

} // end getReferenceTo

/** Removes all entries from this bag. */

public void clear()

{

while (!isEmpty())

remove();

} // end clear

/** Removes one unspecified entry from this bag, if possible.

@return Either the removed entry, if the removal

was successful, or null. */

public T remove()

{

T result = null;

if (firstNode != null)

{

result = firstNode.data;

firstNode = firstNode.next; // Remove first node from chain

numberOfEntries--;

} // end if

return result;

} // end remove

/** Removes one occurrence of a given entry from this bag, if possible.

@param anEntry The entry to be removed.

@return True if the removal was successful, or false otherwise. */

public boolean remove(T anEntry)

{

boolean result = false;

Node nodeN = getReferenceTo(anEntry);

if (nodeN != null)

{

nodeN.data = firstNode.data; // Replace located entry with entry in first node

firstNode = firstNode.next; // Remove first node

numberOfEntries--;

result = true;

} // end if

return result;

} // end remove

private class Node

{

private T data; // Entry in bag

private Node next; // Link to next node

private Node(T dataPortion)

{

this(dataPortion, null);

} // end constructor

private Node(T dataPortion, Node nextNode)

{

data = dataPortion;

next = nextNode;

} // end constructor

} // end Node

} // end LinkedBag

Problem: Complete Programming Project 5, page 126. Requirements: You will develop the following: a. Develop the class LinkedSet which implements the 'Setlnterface' of Chapter 1. Use the LinkedBag.java file in your implementation b. Develop a test' class which will exercise and test the LinkedSet class. In the test application, create a list of 10 or 12 elements. Remove several elements. Print the list before and after the removal to demonstrate the proper functioning of your methods