Question: /** LinkedBag.java */ public final class LinkedBag implements BagInterface { private Node firstNode; // Reference to first node private int numberOfEntries; public LinkedBag() { firstNode
/**
LinkedBag.java
*/
public final class LinkedBag
{
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
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