Please with homework...did alot of work already and I'm stuck

Question

brain damaged 0 Newbie Poster

15 Years Ago

hi, I'm working on an exercise, i did a lot of work already and i just can't figure where I'm going wrong, this is what I'm trying to achieve

Sample IO

*******************************************************************************
Welcome to PeopleSoft 2
MENU: (A)dd student, (D)elete, (L)ist, (S)ort, e(X)it
a
Enter the student number
MSXMIC001
Enter the name
Mickey Mouse
Done
MENU: (A)dd student, (D)elete, (L)ist, (S)ort, e(X)it
a
Enter the student number
CHPALV001
Enter the name
Alvin the Chipmunk
Done
MENU: (A)dd student, (D)elete, (L)ist, (S)ort, e(X)it
a
Enter the student number
DCKDON002
Enter the name
Donald Duck
Done
MENU: (A)dd student, (D)elete, (L)ist, (S)ort, e(X)it
l
Student: DCKDON002, Donald Duck
Student: CHPALV001, Alvin the Chipmunk
Student: MSXMIC001, Mickey Mouse
Done
MENU: (A)dd student, (D)elete, (L)ist, (S)ort, e(X)it
s
Done
MENU: (A)dd student, (D)elete, (L)ist, (S)ort, e(X)it
l
Student: CHPALV001, Alvin the Chipmunk
Student: DCKDON002, Donald Duck
Student: MSXMIC001, Mickey Mouse
Done
MENU: (A)dd student, (D)elete, (L)ist, (S)ort, e(X)it
d
Enter the student number
DCKDON002
Done
MENU: (A)dd student, (D)elete, (L)ist, (S)ort, e(X)it
l
Student: CHPALV001, Alvin the Chipmunk
Student: MSXMIC001, Mickey Mouse
Done
MENU: (A)dd student, (D)elete, (L)ist, (S)ort, e(X)it
x
***************************************************************

and this is my code so far, that won't work....

*******************************************************************************************
import java.util.NoSuchElementException;
import java.util.Scanner;

public class LinkedList2
{   private class Node
    {
            private String name;
            private String stuName;
            private Node link;


    public Node()
    {
        link = null;
        name = null;
        stuName = null;
    }

    public Node(String newStuName, String newName, Node linkValue)
    {
        setData(newStuName, newName);
        link = linkValue;
    }
    public void setData(String newStuName, String newName)
    {
        name = newName;
        stuName = newStuName;
    }
    public void setLink(Node newLink)
    {
        link = newLink;
    }
    public String getStuName()
    {
        return stuName;
    }
    public String getName()
    {
        return name;
    }
    public Node getLink()
    {
        return link;
    }
    }//end of node inner class

    public class List2Iterator//inner class for iterators for linkedlist2
    {   
        private Node position;
        private Node previous;

        public List2Iterator()
        {
            position = head;
            previous = null;
        }
        public void restart()
        {
            position = head;
            previous = null;
        }
        public String next()
        {
            if(!hasNext())
                throw new NoSuchElementException();
            String toReturn = position.stuName;
            previous = position;
            position = position.link;
            return toReturn;
        }
        public boolean hasNext()
        {
            return(position != null);
        }
        public String peek()
        {
            if(!hasNext())
                throw new IllegalStateException();
                return position.stuName;
        }
        public void addHare(String newData)
        {
            if(position == null && previous != null)//if at end o list

            previous.link = new Node(newData, null);
            else if(position == null || previous == null)
            LinkedList2.this.addToStart(newData);

            else{
                Node temp = new Node(newData, position);
                previous.link = temp;
                previous = temp;
            }
        }
        public void changeHare(String newData)
        {
            if(position == null)
                throw new IllegalStateException();
                else
                position.stuName = newData;
        }
        public void delete()
        {
            if(position == null)
                throw new IllegalStateException();
                else if(previous == null)
                {
                    head = head.link;
                    position = head;
                }
                else
                {
                    previous.link = position.link;
                    position = position.link;
                }
        }
    }
        private Node head;

        public List2Iterator iterator()
        {
            return new List2Iterator();
        }
        public LinkedList2()
        {
            head = null;//adds node at the stat of the list with the specified data
        }
        public void addToStart(String itemStuName, String itemName)
        {
        head = new Node1(itemStuName, itemName, head);
        }
        }
        public boolean deleteHeadNode()
        {
            if(head != null){

                head = head.link;
                return true;
            }
            else 
            return false;
        }
        /*public int size()//return number of nodes in the list
        {
            int count = 0;
            Node position = head;
            while(position != null)
            {
                count++;
                position = position.link;
            }
            return count;
        }*/
        public boolean contains(String stuName, String name)
        {
        return (find(stuName, name) != null); 
        }
        private Node find(String target)
        {
            Node position = head;
            String itemAtPosition;
            while (position != null)
            {
                itemAtPosition = position.stuName;
                if(itemAtPosition.equals(target))
                    return position;
                    position = position.link;
            }
            return null; //target wan not found
        }
        public void outPutList()
        {
            Node position = head;
            while(position != null);
            {
                System.out.println(position.stuName);
                position = position.link;
            }
        }
        public boolean isEmpty()
        {
            return(head == null);
        }
        public void clear()
        {
            head = null;
        }
        public boolean equals(Object otherObject)
        {
            if(otherObject == null)
                return false;
                else if(getClass() != otherObject.getClass())
                    return false;
                else{
                    LinkedList2 otherList = (LinkedList2)otherObject;
                    if(size() != otherList.size())
                        return false;
                        Node position = head;
                        Node otherPosition = otherList.head;
                        while(position != null)
                        {   
                            if((!(position.item.equals(otherPosition.stuName))))
                                return false;
                            position = position.link;
                            otherPosition = otherPosition.link;
                        }
                        return true;//a mis match was not found
                    }
        }


        public static void main(String[] args)
        {
            Scanner keyboard = new Scanner(System.in);

            LinkedList2 list = new LinkedList2();
            LinkedList2.List2Iterator i = list.iterator();

            System.out.println("Welcome to PeopleSoft 2");

            int choice = keyboard.nextInt();
            while(choice !== 5)
            {
                System.out.println("MENU: (A)dd student, (D)elete, (L)ist, (S)ort, e(X)it");            
                switch(choice)
                {
                    case 1:
                    System.out.println("Enter the student number");
                    stuNum = keyboard.next();
                    System.out.println("Enter the Student name");
                    name = keyboard.next();
                    list.addToStart(studentNum,name);
                    System.out.println("Done");
                    break;

                    case 2:
                    System.out.println("Enter student number");
                    stuName = keyboard.next();
                    i.restart();
                    i.next();
                    System.out.println("Will delete the node for; " + i.peek());
                    i.delete();
                    System.out.println("Done");
                    break;

                    case 3:
                    System.out.println("list now contains:");
                    i.restart();
                    while(i.hasNext())
                    System.out.println("Student: " + i.next());
                    System.out.println();
                    System.out.println("Done");
                    break;

                    case 5:
                    System.exit(0);
                    break;

                    default:
                    System.out.println("Error,please check your input again");
                    break;  
                }
            }       



        }


}
********************************************************************************************

please help me see where I'm going wrong.

java

Edited 11 Years Ago by mike_2000_17 because: Fixed formatting

3 Contributors
4 Replies
161 Views
12 Hours Discussion Span
Latest Post 15 Years Ago Latest Post by jwenting

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jwenting 1,889 duckman

15 Years Ago

tons of unformatted code, no description of what "goes wrong", no nothing.
You'll have to do better than that if you expect us to fix the code you pulled from some other website for you, kid.

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stultuske 1,116 Posting Maven Featured Poster · Answer 1 · 2008-09-17T20:33:08+00:00

could you put the code between [ CODE] [ /CODE] tags to make it more readable and also give the errors you are getting? might make it a lot easier to actually help you out with this one

brain damaged 0 Newbie Poster · Answer 2 · 2008-09-18T01:12:58+00:00

hi again, sorry I did not give enough information,
when i compile, I get about 70 lines of errors saying "enum expected" what i really have trouble with is letting the user enter all the information. I'm also having trouble writing a suitable delete() method....the one in my code is from my textbook example, actualy almost of all the code...all I really need is how do let the user enter all the data and do I need an array for (studentNumber and name)?..I'm a bit frustrated now.
[import java.util.NoSuchElementException;
import java.util.Scanner;

public class LinkedList2
{ private class Node
{
private String name;
private String stuName;
private Node link;

public Node()
{
link = null;
name = null;
stuName = null;
}

public Node(String newStuName, String newName, Node linkValue)
{
setData(newStuName, newName);
link = linkValue;
}
public void setData(String newStuName, String newName)
{
name = newName;
stuName = newStuName;
}
public void setLink(Node newLink)
{
link = newLink;
}
public String getStuName()
{
return stuName;
}
public String getName()
{
return name;
}
public Node getLink()
{
return link;
}
}//end of node inner class

public class List2Iterator//inner class for iterators for linkedlist2
{
private Node position;
private Node previous;

public List2Iterator()
{
position = head;
previous = null;
}
public void restart()
{
position = head;
previous = null;
}
public String next()
{
if(!hasNext())
throw new NoSuchElementException();
String toReturn = position.stuName;
previous = position;
position = position.link;
return toReturn;
}
public boolean hasNext()
{
return(position != null);
}
public String peek()
{
if(!hasNext())
throw new IllegalStateException();
return position.stuName;
}
public void addHare(String newData)
{
if(position == null && previous != null)//if at end o list

previous.link = new Node(newData, null);
else if(position == null || previous == null)
LinkedList2.this.addToStart(newData);

else{
Node temp = new Node(newData, position);
previous.link = temp;
previous = temp;
}
}
public void changeHare(String newData)
{
if(position == null)
throw new IllegalStateException();
else
position.stuName = newData;
}
public void delete()
{
if(position == null)
throw new IllegalStateException();
else if(previous == null)
{
head = head.link;
position = head;
}
else
{
previous.link = position.link;
position = position.link;
}
}
}
private Node head;

public List2Iterator iterator()
{
return new List2Iterator();
}
public LinkedList2()
{
head = null;//adds node at the stat of the list with the specified data
}
public void addToStart(String itemStuName, String itemName)
{
head = new Node1(itemStuName, itemName, head);
}
}
public boolean deleteHeadNode()
{
if(head != null){

head = head.link;
return true;
}
else
return false;
}
/*public int size()//return number of nodes in the list
{
int count = 0;
Node position = head;
while(position != null)
{
count++;
position = position.link;
}
return count;
}*/
public boolean contains(String stuName, String name)
{
return (find(stuName, name) != null);
}
private Node find(String target)
{
Node position = head;
String itemAtPosition;
while (position != null)
{
itemAtPosition = position.stuName;
if(itemAtPosition.equals(target))
return position;
position = position.link;
}
return null; //target wan not found
}
public void outPutList()
{
Node position = head;
while(position != null);
{
System.out.println(position.stuName);
position = position.link;
}
}
public boolean isEmpty()
{
return(head == null);
}
public void clear()
{
head = null;
}
public boolean equals(Object otherObject)
{
if(otherObject == null)
return false;
else if(getClass() != otherObject.getClass())
return false;
else{
LinkedList2 otherList = (LinkedList2)otherObject;
if(size() != otherList.size())
return false;
Node position = head;
Node otherPosition = otherList.head;
while(position != null)
{
if((!(position.item.equals(otherPosition.stuName))))
return false;
position = position.link;
otherPosition = otherPosition.link;
}
return true;//a mis match was not found
}
}

public static void main(String[] args)
{
Scanner keyboard = new Scanner(System.in);

LinkedList2 list = new LinkedList2();
LinkedList2.List2Iterator i = list.iterator();

System.out.println("Welcome to PeopleSoft 2");

int choice = keyboard.nextInt();
while(choice !== 5)
{
System.out.println("MENU: (A)dd student, (D)elete, (L)ist, (S)ort, e(X)it");
switch(choice)
{
case 1:
System.out.println("Enter the student number");
stuNum = keyboard.next();
System.out.println("Enter the Student name");
name = keyboard.next();
list.addToStart(studentNum,name);
System.out.println("Done");
break;

case 2:
System.out.println("Enter student number");
stuName = keyboard.next();
i.restart();
i.next();
System.out.println("Will delete the node for; " + i.peek());
i.delete();
System.out.println("Done");
break;

case 3:
System.out.println("list now contains:");
i.restart();
while(i.hasNext())
System.out.println("Student: " + i.next());
System.out.println();
System.out.println("Done");
break;

case 5:
System.exit(0);
break;

default:
System.out.println("Error,please check your input again");
break;
}
}
]

jwenting 1,889 duckman Team Colleague · Answer 3 · 2008-09-18T02:13:28+00:00

more unformatted code...
And those error messages are quite clear. Learn to interpret them.

Please with homework...did alot of work already and I'm stuck

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