For each task, zip and submit all your source java code files.

Objective: Implement Link List Write a class that maintains the scores for a game application. The gamescore.txt contains player name and score data record fields separated by comma. Implement the addition and removal function to update the database. Reject adding duplicate name to the list. For Removal function, uses the name field to select record to remove the game score record. Display error message if user tried to delete a name that was not on the list. Optional sort the list by score.

Download List.java, LList.java, DLink.java, GameEntry.java and gamescore.txt from Moodle

Objective: Manipulate the Linked List Pointer. Add a reverse list method in LList.java or create a subclass to reverse the order of the linked list. Print the original linked list and the reverse ordered linked list at the end of program. You can either use the test.dat or use the gamescore.txt to test the reverse method.

gamescore.txt : Mike,1105 Rob,750 Paul,720 Anna,660 Rose,590 Jack,510

List.java : /** List ADT */ public interface List { /** Remove all contents from the list, so it is once again empty. Client is responsible for reclaiming storage used by the list elements. */ public void clear();

/** Insert an element at the current location. The client must ensure that the list's capacity is not exceeded. @param item The element to be inserted. */ public void insert(E item);

/** Append an element at the end of the list. The client must ensure that the list's capacity is not exceeded. @param item The element to be appended. */ public void append(E item);

/** Remove and return the current element. @return The element that was removed. */ public E remove();

/** Set the current position to the start of the list */ public void moveToStart();

/** Set the current position to the end of the list */ public void moveToEnd();

/** Move the current position one step left. No change if already at beginning. */ public void prev();

/** Move the current position one step right. No change if already at end. */ public void next();

/** @return The number of elements in the list. */ public int length();

/** @return The position of the current element. */ public int currPos();

/** Set current position. @param pos The position to make current. */ public void moveToPos(int pos);

/** @return The current element. */ public E getValue(); }

LList.java :

// Doubly linked list implementation

class LList implements List {

private DLink head; // Pointer to list header

private DLink tail; // Pointer to last element in list

protected DLink curr; // Pointer ahead of current element

int cnt; // Size of list

//Constructors

LList(int size) { this(); } // Ignore size

LList() {

curr = head = new DLink(null, null); // Create header node

tail = new DLink(head, null);

head.setNext(tail);

cnt = 0;

}

public void clear() { // Remove all elements from list

head.setNext(null); // Drop access to rest of links

curr = head = new DLink(null, null); // Create header node

tail = new DLink(head, null);

head.setNext(tail);

cnt = 0;

}

public void moveToStart() // Set curr at list start

{ curr = head; }

public void moveToEnd() // Set curr at list end

{ curr = tail.prev(); }

/** Insert "it" at current position */

public void insert(E it) {

curr.setNext(new DLink(it, curr, curr.next()));

curr.next().next().setPrev(curr.next());

cnt++;

}

/** Append "it" to list */

public void append(E it) {

tail.setPrev(new DLink(it, tail.prev(), tail));

tail.prev().prev().setNext(tail.prev());

cnt++;

}

/** Remove and return current element */

public E remove() {

if (curr.next() == tail) return null; // Nothing to remove

E it = curr.next().element(); // Remember value

curr.next().next().setPrev(curr);

curr.setNext(curr.next().next()); // Remove from list

cnt--; // Decrement the count

return it; // Return value removed

}

/** Move curr one step left; no change if at front */

public void prev() {

if (curr != head) // Can't back up from list head

curr = curr.prev();

}

// Move curr one step right; no change if at end

public void next()

{ if (curr != tail.prev()) curr = curr.next(); }

public int length() { return cnt; }

// Return the position of the current element

public int currPos() {

DLink temp = head;

int i;

for (i=0; curr != temp; i++)

temp = temp.next();

return i;

}

// Move down list to "pos" position

public void moveToPos(int pos) {

assert (pos>=0) && (pos<=cnt) : "Position out of range";

curr = head;

for(int i=0; i

}

public E getValue() { // Return current element

if (curr.next() == tail) return null;

return curr.next().element();

}

// Extra stuff not printed in the book.

/**

* Generate a human-readable representation of this list's contents

* that looks something like this: < 1 2 3 | 4 5 6 >. The vertical

* bar represents the current location of the fence. This method

* uses toString() on the individual elements.

* @return The string representation of this list

*/

public String toString()

{

// Save the current position of the list

int oldPos = currPos();

int length = length();

StringBuffer out = new StringBuffer((length() + 1) * 4);

moveToStart();

out.append("< ");

for (int i = 0; i < oldPos; i++) {

if (getValue()!=null)

{

out.append(getValue());

out.append(" ");

}

next();

}

out.append("| ");

for (int i = oldPos; i < length; i++) {

out.append(getValue());

out.append(" ");

next();

}

out.append(">");

moveToPos(oldPos); // Reset the fence to its original position

return out.toString();

}

}

DLink.java : /** Doubly linked list node */ class DLink { private E element; // Value for this node private DLink next; // Pointer to next node in list private DLink prev; // Pointer to previous node

/** Constructors */ DLink(E it, DLink p, DLink n) { element = it; prev = p; next = n; } DLink(DLink p, DLink n) { prev = p; next = n; }

/** Get and set methods for the data members */ DLink next() { return next; } DLink setNext(DLink nextval) { return next = nextval; } DLink prev() { return prev; } DLink setPrev(DLink prevval) { return prev = prevval; } E element() { return element; } E setElement(E it) { return element = it; } }

GameEntry.java : public class GameEntry { protected String name; protected int score;

public GameEntry(String n, int s) { name = n; score = s; }

public String getName() {return name;}

public int getScore() {return score;}

public String toString() { return "("+name+","+score+")"; }

}