Question

In 6A, you created an object class encapsulating a Trivia Game which INHERITS from Game.

Now that you have successfully created Trivia objects, you will continue 6B by creating a linked list of trivia objects. Add the linked list code to the Trivia class.

Your linked list code should include the following: a TriviaNode class with the attributes:

1. trivia game - Trivia object

2. next- TriviaNode

3. write the constructor, accessor, mutator and toString methods.

A TriviaLinkedList Class which should include the following attributes:

1. head - TriviaNode

2. number of items – integer

3. write the code for the constructor, accessor and mutator, and toString methods.

4. methods to insert a triviaNode on the list - You may assume inserts always insert as the first node in the list.  

5. write a method to delete a node by passing the node id of the game to delete. Take into consideration that the game may not exist in the list. Your method should let the user know that the node was successfully deleted or not.

Write a client to test all aspects - creating trivia objects, inserting the objects as nodes to the list, deleting a node by passing the id of the trivia game. Print out the list every time you make a change such as adding a node and deleting a node. You should create at least 5 objects to be inserted to your list, then delete at least 1. Also, test deleting an object that is not in the list.

Answer 1

Code implemented in JAVA

Filename: TriviaNode.java

public class TriviaNode<E> {
public Trivia element;
public TriviaNode<E> next;

public TriviaNode(Trivia element) {
this.element = element;
}

public Trivia getElement() {
return element;
}

public TriviaNode<E> getNext() {
return next;
}

public void setNext(TriviaNode<E> next) {
this.next = next;
}

@Override
public String toString() {
return "TriviaNode{" +
"element=" + element +
", next=" + next +
'}';
}
}

Filename: TriviaLinkedList.java

public class TriviaLinkedList {
TriviaNode head, tail;
private int size = 0;

public TriviaLinkedList() {
}

public void addFirst(Trivia e){
TriviaNode newNode = new TriviaNode(e);
newNode.next = head;
head = newNode;
size++;

if (tail == null){
tail = head;
}
}

public void addLast(Trivia e){
TriviaNode newNode = new TriviaNode(e);

if (tail == null){
head = newNode;
tail = newNode;
} else {
tail.next = newNode;
tail = newNode;
}

size++;
}

public void insert(Trivia e){
insert(0, e);
}

public void insert(int index, Trivia e){
if (index == 0){
addFirst(e);
} else if (index >= size){
addLast(e);
} else {
TriviaNode cur = head;
for (int i = 1; i < index; i++) {
cur = cur.next;
}
TriviaNode tmp = cur.next;
cur.next = new TriviaNode(e);
(cur.next).next = tmp;
size++;
}
}

public Trivia removeFirst(){
if (size == 0)
return null;
else {
TriviaNode temp = head;
head = head.next;
size--;
if(head == null){
tail = null;
}
return temp.element;
}
}

public Trivia removeLast(){
if (size == 0){
return null;
} else if (size == 1){
TriviaNode tmp = head;
head = null;
tail = null;
size = 0;
return tmp.element;
} else {
TriviaNode cur = head;

for (int i = 0; i < size - 2; i++) {
cur = cur.next;
}

TriviaNode tmp = tail;
tail = cur;
tail.next = null;
size--;
return tmp.element;

}
}

public Trivia remove(int index){
if (index < 0 || index >= size){
return null;
} else if (index == 0){
return removeFirst();
} else if (index == size - 1){
return removeLast();
} else {
TriviaNode pre = head;

for (int i = 1; i < index; i++) {
pre = pre.next;
}

TriviaNode cur = pre.next;
pre.next = cur.next;
size--;

return cur.element;
}
}

public Trivia removeByID(int id){
TriviaNode cur = head;
int index = 0;
while(cur != null){
if (id == cur.element.getTriviaGameID())
return remove(index);
else
cur = cur.next;
index++;
}

return null;
}

@Override
public String toString() {
return "TriviaLinkedList{" +
"head=" + head +
", tail=" + tail +
", size=" + size +
'}';
}
}

Filename: Trivia.java

public class Trivia extends Game {
int triviaGameID;
double ultimatePrizeMoney;
int numberOfQuestionsThatMustBeAnsweredToWin;

public Trivia(String description, int triviaGameID, double ultimatePrizeMoney, int numberOfQuestionsThatMustBeAnsweredToWin) {
super(description);
this.triviaGameID = triviaGameID;
this.ultimatePrizeMoney = ultimatePrizeMoney;
this.numberOfQuestionsThatMustBeAnsweredToWin = numberOfQuestionsThatMustBeAnsweredToWin;
}

public int getTriviaGameID() {
return triviaGameID;
}

public void setTriviaGameID(int triviaGameID) {
this.triviaGameID = triviaGameID;
}

public double getUltimatePrizeMoney() {
return ultimatePrizeMoney;
}

public void setUltimatePrizeMoney(double ultimatePrizeMoney) {
this.ultimatePrizeMoney = ultimatePrizeMoney;
}

public int getNumberOfQuestionsThatMustBeAnsweredToWin() {
return numberOfQuestionsThatMustBeAnsweredToWin;
}

public void setNumberOfQuestionsThatMustBeAnsweredToWin(int numberOfQuestionsThatMustBeAnsweredToWin) {
this.numberOfQuestionsThatMustBeAnsweredToWin = numberOfQuestionsThatMustBeAnsweredToWin;
}

@Override
public String toString() {
return "Trivia{" +
"triviaGameID=" + triviaGameID +
", ultimatePrizeMoney=" + ultimatePrizeMoney +
", numberOfQuestionsThatMustBeAnsweredToWin=" + numberOfQuestionsThatMustBeAnsweredToWin +
", description='" + description + '\'' +
'}';
}
}

Filename: Main.java

public class Main {

public static void main(String[] args) {
Trivia t1 = new Trivia("Trivia Game 1", 1, 1.0, 2);
Trivia t2 = new Trivia("Trivia Game 2", 2, 1.0, 2);
Trivia t3 = new Trivia("Trivia Game 3", 3, 1.0, 2);
Trivia t4 = new Trivia("Trivia Game 4", 4, 1.0, 2);
Trivia t5 = new Trivia("Trivia Game 5", 5, 1.0, 2);

System.out.println("Create Blank Linked List");
TriviaLinkedList ll = new TriviaLinkedList();
System.out.println(ll);
printLinkedList(ll);

System.out.println("Insert 5 Trivia objects");
addAndPrint(ll, t5);
addAndPrint(ll, t4);
addAndPrint(ll, t3);
addAndPrint(ll, t2);
addAndPrint(ll, t1);

System.out.println("Remove node by triviaGameID");
ll.removeByID(3);
printLinkedList(ll);

System.out.println("Remove node that doesn't exist");

Trivia removed = ll.removeByID(23);
if (removed == null) {
System.out.println("Node Does Not Exist");
}
printLinkedList(ll);
}

public static void printLinkedList(TriviaLinkedList ll){
TriviaNode current = ll.head;

System.out.print("\n{\n");
while (current != null){
System.out.println("\t" + current.element);
current = current.next;
}

System.out.print("}\n\n");

}

public static void addAndPrint(TriviaLinkedList ll, Trivia t){
ll.insert(t);
System.out.println(ll);
printLinkedList(ll);
}
}

Filename: Game.java

public class Game {
String description;

public Game() {
this("This Game has no description");
}

public Game(String description) {
this.description = description;
}

public String getDescription() {
return description;
}

public void setDescription(String description) {
this.description = description;
}

@Override
public String toString() {
return "Game{" +
"description='" + description + '\'' +
'}';
}
}

Working Code Output Screenshot:

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