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//assigment10.java

import java.io.*;

public class Assignment10

{

public static void main(String[] args)

{

char input1;

String inputInfo = new String();

int operation2;

String line = new String();

//create a linked list to be used in this method.

LinkedList list1 = new LinkedList();

try {

// print out the menu

printMenu();

// create a BufferedReader object to read input from a keyboard

BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in));

do {

System.out.print("What action would you like to perform? ");

line = stdin.readLine().trim(); //read a line

input1 = line.charAt(0);

input1 = Character.toUpperCase(input1);

if(line.length() == 1) { //check if a user entered only one character

switch(input1) {

case 'A': //Add String

System.out.print("Please enter a string to add: ");

String str1 = stdin.readLine().trim();

System.out.print("Please enter an index to add: ");

inputInfo = stdin.readLine().trim();

int addIndex = Integer.parseInt(inputInfo);

list1.addElement(addIndex, str1);

break;

case 'D': //Search for the Index of a String

System.out.print("Please enter a string to search: ");

inputInfo = stdin.readLine().trim();

operation2=list1.searchElement(inputInfo);

if(operation2 > -1)

System.out.print("string found at " + operation2 + " ");

else

System.out.print("string not found ");

break;

case 'E': //Search for String at an Index

System.out.print("Please enter an index to search: ");

inputInfo = stdin.readLine().trim();

int searchIndex = Integer.parseInt(inputInfo);

System.out.print("string at the given index is " + list1.getElement(searchIndex) + " ");

break;

case 'L': //List Strings

System.out.print(list1.toString());

break;

case 'O': // List Current Size

System.out.print("The current size is " + list1.size() + " ");

break;

case 'Q': break; //Quit

case 'R': //Remove Last Few

System.out.print("Please enter a number of elements to be removed from the end of the linked list: ");

inputInfo = stdin.readLine().trim();

int howMany = Integer.parseInt(inputInfo);

list1.removeLastFew(howMany);

break;

case 'S': //Set String

System.out.print("Please enter a string to set: ");

String str2 = stdin.readLine().trim();

System.out.print("Please enter an index to set: ");

inputInfo = stdin.readLine().trim();

int setIndex = Integer.parseInt(inputInfo);

list1.setElement(setIndex, str2);

break;

case 'T': //Reverse

list1.reverse();

System.out.print("list reversed ");

break;

case '?': printMenu(); break; //Display Menu

default: System.out.print("Unknown action "); break;

} // switch(input1)

}

else

System.out.print("Unknown action ");

} while (input1 != 'Q' || line.length() != 1); // do-while

}

catch (IOException exception)

{

System.out.print("IO Exception ");

} // try-catch(IOException)

} // main()

/** The method printMenu displays the menu to a user **/

public static void printMenu()

{

System.out.print("Choice\t\tAction " +

"------\t\t------ " +

"A\t\tAdd String " +

"D\t\tSearch for Index " +

"E\t\tSearch for String " +

"L\t\tList Strings " +

"O\t\tList Current Size " +

"Q\t\tQuit " +

"R\t\tRemove Last Few " +

"S\t\tSet String " +

"T\t\tReverse " +

"?\t\tDisplay Help ");

} // printMenu()

} // class Assignment10

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//Linkedlist.java

import java.util.*;

public class LinkedList { /ested class to represent a node private class Node { public Object data; public Node next; }

//only instance variable that points to the first node. private Node first;

// Constructs an empty linked list. public LinkedList() { first = null; }

// Returns the first element in the linked list. public Object getFirst() { if (first == null) { NoSuchElementException ex = new NoSuchElementException(); throw ex; } else return first.data; }

// Removes the first element in the linked list. public Object removeFirst() { if (first == null) { NoSuchElementException ex = new NoSuchElementException(); throw ex; } else { Object element = first.data; first = first.next; //change the reference since it's removed. return element; } }

// Adds an element to the front of the linked list. public void addFirst(Object element) { //create a new node Node newNode = new Node(); newNode.data = element; newNode.next = first; //change the first reference to the new node. first = newNode; }

// Returns an iterator for iterating through this list. public ListIterator listIterator() { return new LinkedListIterator(); }

/********************************************************* Add your methods here *********************************************************/

/ested class to define its iterator private class LinkedListIterator implements ListIterator { private Node position; //current position private Node previous; //it is used for remove() method

// Constructs an iterator that points to the front // of the linked list.

public LinkedListIterator() { position = null; previous = null; }

// Tests if there is an element after the iterator position. public boolean hasNext() { if (position == null) /ot traversed yet { if (first != null) return true; else return false; } else { if (position.next != null) return true; else return false; } }

// Moves the iterator past the next element, and returns // the traversed element's data. public Object next() { if (!hasNext()) { NoSuchElementException ex = new NoSuchElementException(); throw ex; } else { previous = position; // Remember for remove

if (position == null) position = first; else position = position.next;

return position.data; } }

// Adds an element after the iterator position // and moves the iterator past the inserted element. public void add(Object element) { if (position == null) /ever traversed yet { addFirst(element); position = first; } else { //making a new node to add Node newNode = new Node(); newNode.data = element; newNode.next = position.next; //change the link to insert the new node position.next = newNode; //move the position forward to the new node position = newNode; } //this means that we cannot call remove() right after add() previous = position; }

// Removes the last traversed element. This method may // only be called after a call to the next() method. public void remove() { if (previous == position) /ot after next() is called { IllegalStateException ex = new IllegalStateException(); throw ex; } else { if (position == first) { removeFirst(); } else { previous.next = position.next; //removing } //stepping back //this also means that remove() cannot be called twice in a row. position = previous; } }

// Sets the last traversed element to a different value. public void set(Object element) { if (position == null) { NoSuchElementException ex = new NoSuchElementException(); throw ex; } else position.data = element; } } //end of LinkedListIterator class } //end of LinkedList class

----------------------------------------------------------------------------------------------------------------

//listlterator.java

public interface ListIterator { //Move Moves the iterator past the next element. Object next();

// Tests if there is an element after the iterator position. boolean hasNext();

// Adds an element before the iterator position // and moves the iterator past the inserted element. void add(Object element);

// Removes the last traversed element. This method may // only be called after a call to the next() method. void remove();

// Sets the last traversed element to a different value. void set(Object element); }

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input:

A Pink 0 L A Red 0 L C A Black 2 L A Yellow 0 L A White 1 L O L A Indigo 1 L A Blue 5 L A Green 0 L A Gray 0 L Q

Output:

Choice Action

------ ------

A Add String

D Search for Index

E Search for String

L List Strings

O List Current Size

Q Quit

R Remove Last Few

S Set String

T Reverse

? Display Help

What action would you like to perform?

Please enter a string to add:

Please enter an index to add:

What action would you like to perform?

{ Pink }

What action would you like to perform?

Please enter a string to add:

Please enter an index to add:

What action would you like to perform?

{ Red Pink }

What action would you like to perform?

Unknown action

What action would you like to perform?

Please enter a string to add:

Please enter an index to add:

What action would you like to perform?

{ Red Pink Black }

What action would you like to perform?

Please enter a string to add:

Please enter an index to add:

What action would you like to perform?

{ Yellow Red Pink Black }

What action would you like to perform?

Please enter a string to add:

Please enter an index to add:

What action would you like to perform?

{ Yellow White Red Pink Black }

What action would you like to perform?

The current size is 5

What action would you like to perform?

{ Yellow White Red Pink Black }

What action would you like to perform?

Please enter a string to add:

Please enter an index to add:

What action would you like to perform?

{ Yellow Indigo White Red Pink Black }

What action would you like to perform?

Please enter a string to add:

Please enter an index to add:

What action would you like to perform?

{ Yellow Indigo White Red Pink Blue Black }

What action would you like to perform?

Please enter a string to add:

Please enter an index to add:

What action would you like to perform?

{ Green Yellow Indigo White Red Pink Blue Black }

What action would you like to perform?

Please enter a string to add:

Please enter an index to add:

What action would you like to perform?

{ Gray Green Yellow Indigo White Red Pink Blue Black }

What action would you like to perform?

Assignment 10 ListIterator main(String[D void printMenu0void LinkedListIterator -position Node previous Node L+hasNext0:boolean LinkedListIterator0 +hasNextO.boolean tnext0 Object tadd(Object) void +removeO:void +set(Object) void +next0 Object +add(Object) void tremove0:void +set (Object).void LinkedList first Node +LinkedList0 tgetFirst0: Object tremoveFirst0: Object +addFirst (Object).void HistIterator: ListIterator +toString0:String +sizeO int +searchElement(Object)int +getElement (int) Object +setElement int, Object) void +addElement(int, Object) void +removeLastFew(int)void treverseO:void Node +data Object +- ext: Node