Chapter 12, Problem 10E

Modified code for “StringLinkedList” class:

The modified code for “StringLinkedList” class is given below:

Filename: “ListNode.java”

//Define "ListNode" class

public class ListNode

{

/* This class is same as the code in Listing 12.4 of textbook */

}

Filename: “StringLinkedList.java”

/* This class is same as the code in Listing 12.5 of textbook */

//Define "StringLinkedList" class

public class StringLinkedList

{

  private ListNode head;

  /* Create constructor for "StringLinkedList" class*/

  public StringLinkedList()

  {

  head = null;

  }

  /* Displays the data on the list.*/

  public void showList()

  {

  ListNode position = head;

  while (position != null)

  {

  System.out.println(position.getData());

  position = position.getLink();

  }

  }

  /* Returns the number of nodes on the list.*/

  public int length()

  {

  int count = 0;

  ListNode position = head;

  while (position != null)

  {

  count++;

  position = position.getLink();

  }

  return count;

  }

/* Adds a node containing the data addData at the start of the list.*/

  public void addANodeToStart(String addData)

  {

  head = new ListNode(addData, head);

  }

/* Method definition for add a node at the end of list */

public void addANodeToEnd(String addData)

{

  /* If head is null or empty, then */

  if(head == null)

  //Add node to the front

  addANodeToStart(addData);

  //Otherwise

  else

  {

  /* Assign "s" to "head" */

  ListNode s = head;

  //Compute the last node in the list

  while(s.getLink() != null)

  {

  s = s.getLink();

  }

  // Add in the node

  ListNode c = new ListNode(addData, null);

  s.setLink(c);

  }

  }

  /* Deletes the first node on the list.*/

  public void deleteHeadNode()

  {

  if (head != null)

  head = head.getLink();

  else

  {

System.out.println("Deleting from an empty list.");

System.exit(0);

}

}

/* Method definition for deletes the last node on the list */

public void deleteLastNode()

  {

  /* If head is null or empty, then */

  if (head == null)

  {

  //Display given message

System.out.println("Deleting from an empty list.");

System.exit(0);

}

  /* If "head.getLink()" is null, then */

  else if (head.getLink() == null)

  {

/* Delete first node in the list by calling method "deleteHeadNode" */

deleteHeadNode();

}

  //Otherwise

  else

  {

  //Set "s" to "head"

  ListNode s = head;

  //Look for the node before the final node

  while(s.getLink().getLink() != null)

  s = s.getLink();

  //Unlink the last node

  s.setLink(null);

  }

  }

  /* Sees whether target is on the list.*/

  public boolean onList(String target)

  {

  return find(target) != null;

  }

  // Returns a reference to the first node containing the

// target data. If target is not on the list, returns null.

private ListNode find(String target)

{

boolean found = false;

ListNode position = head;

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

{

  String dataAtPosition = position.getData();

  if (dataAtPosition.equals(target))

  found = true;

  else

  position = position.getLink();

  }

  return position;

  }

}

Modified Filename: “StringLinkedListDemo.java”

//Define "StringLinkedListDemo" class

public class Main

{

  //Define main function

  public static void main(String[] args)

  {

//Create object "list" from "StringLinkedList" class

  StringLinkedList list = new StringLinkedList();

/* Add three node to list by calling the method "addANodeToStart" */

list...