declaring and using a linked list

[AZRebelCowgirl73]

This is what I have so far:

My program!

import java.util.*;
import java.lang.*;
import java.io.*;
import ch06.lists.*;
 
public class UIandDB {
 
    public static void main (String [] args) throws IOException {
 
      Scanner stdin = new Scanner(System.in);
 
      System.out.println("Car Part Database");
 
      //use a RefSortedList
 
      String skip;            //skip end of line after reading an integer
      boolean keepGoing;      //flag for "choose operation" loop
      int operation;            //indicates user's choice of operations
 
      keepGoing = true;
      while (keepGoing) {
          System.out.println("Choose and Operation:");
          //insert command
          System.out.println("1: Add new car part to the database");
          //delete command
          System.out.println("2: Remove a car part from the database");
          //print all parts command
          System.out.println("3: Print all car parts currently in the database");
          //print a part command
          System.out.println("4: Print a particular car part currently in the database");
          //increase part stock command
          System.out.println("5: Increase current stock level for a car part in the database");
          //deliver part command
          System.out.println("6: Deliver a certain amount of a car part in the database to a customer");
          //exit command
          System.out.println("7: Exit the car part database");
          if (stdin.hasNextInt()) {
            operation = stdin.nextInt();
          }
          else {
            System.out.println("Error: you must enter a number between 1 and 7!");
            System.out.println("Terminating Database!");
            return;
          }
          skip = stdin.nextLine();
 
          switch (operation) {
                case 1: //insert command
            //adds new part type to database(partID, partName, partStock, and partPrice)
            //inputted by user
            break;
 
            case 2: //delete command
            //removes a part from the database(part is no longer produced by the company)
            //user inputs partID of the part and it is removed from the database
              break;
 
            case 3: //print all parts command
            //displays on screen all parts in the database
            break;
 
            case 4: //print a part command
            //displays on screen data about a specified car part
            //user inputs partID of the part and it is displayed
            break;
 
            case 5: //increase part stock command
            //increase the available stock of a certain part
            //user inputs partID and quantity to be added to existing part stock
            break;
 
            case 6: //deliver part command
            //deliver a specified quantity of a certain part to customer
            //user inputs partID and the quantity to be delivered
            break;
 
            case 7: //exit command
            //exit the application
            keepGoing = false;
            break;
         }
      }
    System.out.println("Closing the car part database.");
    System.out.println("Thanks for using my program!");
    }
}

This is the CarPart.java file for the information i must collect for each car part!

public class CarPart {
 
      public int partID;
      public String partName;
      public int partStock;
      public double partPrice;
 
      //constructor with parameters
      public CarPart(int ID, String n, int s, double p) {
            partID = ID;
            partName = n;
            partStock = s;
            partPrice = p;
      }//end constructor
 
      //(part ID accessor)
      public int getPartID() {
            return partID;
      }//end method
 
      //(part name accessor)
      public String getPartName() {
            return partName;
      }//end method
 
      //(part stock accessor)
      public int getStock() {
            return partStock;
      }//end method
 
      //(part price accessor)
      public double getPartPrice() {
            return partPrice;
      }//end method
 
      //(transformer method)
      public void addToStock(int add) {
            partStock += add;
      }//end method
 
      //(transformer method)
      public boolean removeFromStock(int remove) {
            if ( remove <= partStock){
                  partStock -= remove;
                  return true;
            } 
            else {
                  return false;
            }
      }//end method
 
      //print method
      public void print() {
            System.out.println(getPartID() + ", " + getPartName() + ", " +  getStock() + ", $"+  getPartPrice());
      }//end method 
 
}

I must reference the following ch.06 files!

//-------------------------------------------------------------------------
// RefSortedList.java         by Dale/Joyce/Weems                 Chapter 6
//
// Implements the SortedListInterface using a linked list.
//-------------------------------------------------------------------------
 
package ch06.lists;
 
import support.LLObjectNode;
 
public class RefSortedList extends RefList implements SortedListInterface  
{
 
  public RefSortedList() 
  {
    super();
  }
 
  public void add(Comparable element)
  // Adds element to this list.
  {
    LLObjectNode prevLoc;     // trailing reference
    LLObjectNode location;    // traveling reference
    Comparable listElement;   // current list element being compared      
    boolean moreToSearch;             
 
    // Set up search for insertion point.
    location = list;
    prevLoc = null;
    moreToSearch = (location != null);
 
    // Find insertion point.
    while (moreToSearch)
    {
      listElement = (Comparable)location.getInfo();
      if (listElement.compareTo(element) < 0)  // list element < add element
      {
         prevLoc = location;
         location = location.getLink();
         moreToSearch = (location != null);   // stop looking at end of list
      }
      else
        moreToSearch = false;     // list element >= add element
    }
 
    // Prepare node for insertion.
    LLObjectNode newNode = new LLObjectNode(element);
 
    // Insert node into list.
    if (prevLoc == null)         
    {
      // Insert as first node.
      newNode.setLink(list);
      list = newNode;
    }
    else
    {
      // Insert elsewhere.
      newNode.setLink(location);
      prevLoc.setLink(newNode);
    }
    numElements++;
  }
}
 
//-------------------------------------------------------------------------
// RefList.java            by Dale/Joyce/Weems                    Chapter 6
//
// Defines constructs for an unbounded reference-based list of objects that
// do not depend on whether the list is unsorted or sorted.
//
// Our intention is for this class to be extended by classes that furnish
// the remaining methods needed to support a list - for example, a method
// that allows objects to be added to the list.
//
// Null elements are not permitted on a list.
//
// One constructor is provided, one that creates an empty list.
//------------------------------------------------------------------------
 
package ch06.lists;
 
import support.LLObjectNode;
 
public class RefList
{
  protected int numElements;          // number of elements in this list
  protected LLObjectNode currentPos;  // current position for iteration
 
  // set by find method
  protected boolean found;         // true if element found, else false
  protected LLObjectNode location; // node containing element, if found
  protected LLObjectNode previous; // node preceeding location
 
  protected LLObjectNode list;     // first node on the list
 
  public RefList()
  {
    numElements = 0;
    list = null;
    currentPos = null;
  }
 
  protected void find(Object target)
  // Searches list for an occurence of an element e such that
  // e.equals(target). If successful, sets instance variables
  // found to true, location to node containing e, and previous
  // to the node that links to location. If not successful, sets 
  // found to false.
  {
    boolean moreToSearch;
    location = list;
    found = false;
 
    moreToSearch = (location != null);
    while (moreToSearch && !found) 
    {
      if (location.getInfo().equals(target))  // if they match
       found = true;
      else
      {
        previous = location;
        location = location.getLink();
        moreToSearch = (location != null);
      }
    }
  }
 
  public int size()
  // Returns the number of elements on this list. 
  {
    return numElements;
  }
 
  public boolean contains (Object element)
  // Returns true if this list contains an element e such that 
  // e.equals(element); otherwise, returns false.
  {
    find(element);
    return found;
  }
 
  public boolean remove (Object element)
  // Removes an element e from this list such that e.equals(element)
  // and returns true; if no such element exists, returns false.
  {
    find(element);
    if (found)
    {
      if (list == location)     
        list = list.getLink();    // remove first node
      else
        previous.setLink(location.getLink());  // remove node at location
 
      numElements--;
    }
    return found;
  }
 
  public Object get(Object element)
  // Returns an element e from this list such that e.equals(element);
  // if no such element exists, returns null.
  {
    find(element);    
    if (found)
      return location.getInfo();
    else
      return null;
  }
 
  public String toString()
  // Returns a nicely formatted string that represents this list.
  {
    LLObjectNode currNode = list;
    String listString = "List:\n";
    while (currNode != null)
    {
      listString = listString + "  " + currNode.getInfo() + "\n";
      currNode = currNode.getLink();
    }
    return listString;
  }  
 
  public void reset()
  // Initializes current position for an iteration through this list,
  // to the first element on this list.
  {
    currentPos  = list;
  }
 
  public Object getNext()
  // Preconditions: The list is not empty
  //                The list has been reset
  //                The list has not been modified since most recent reset
  //
  // Returns the element at the current position on this list.
  // If the current position is the last element, then it advances the value 
  // of the current position to the first element; otherwise, it advances
  // the value of the current position to the next element.
  {
    Object next = currentPos.getInfo();
    if (currentPos.getLink() == null)
      currentPos = list;
    else
      currentPos = currentPos.getLink();
    return next;
  }
}
 
//----------------------------------------------------------------------------
// SortedListInterface.java         by Dale/Joyce/Weems              Chapter 6
//
// Extends the ListInterface with methods specific to sorted lists.
//----------------------------------------------------------------------------
 
package ch06.lists;
 
public interface SortedListInterface extends ListInterface
{
  void add(Comparable element);
  // Adds element to this list. The list remains sorted.
}
 
//----------------------------------------------------------------------------
// ListInterface.java            by Dale/Joyce/Weems                 Chapter 6
//
// Interface that defines methods common to various kinds of list.
// Our intention is that this interface will be extended by other interfaces
// directly related to the specific kind of list. Those interfaces, in turn,
// will be implemented by classes.
//
// The lists are unbounded and allow duplicate elements, but do not allow 
// null elements. As a general precondition, null elements are not passed as 
// arguments to any of the methods.
//
// The list has a special property called the current position - the position 
// of the next element to be accessed by getNext during an iteration through 
// the list. Only reset and getNext affect the current position.
//----------------------------------------------------------------------------
 
package ch06.lists;
 
public interface ListInterface
{
  int size();
  // Returns the number of elements on this list.
 
  boolean contains (Object element);
  // Returns true if this list contains an element e such that 
  // e.equals(element); otherwise, returns false.
 
  boolean remove (Object element);
  // Removes an element e from this list such that e.equals(element)
  // and returns true; if no such element exists, returns false. 
 
  Object get(Object element);
  // Returns an element e from this list such that e.equals(element);
  // if no such element exists, returns null.
 
  String toString();
  // Returns a nicely formatted string that represents this list.
 
  void reset();
  // Initializes current position for an iteration through this list,
  // to the first element on this list.
 
  Object getNext();
  // Preconditions: The list is not empty
  //                The list has been reset
  //                The list has not been modified since the most recent reset
  //
  // Returns the element at the current position on this list.
  // If the current position is the last element, then it advances the value 
  // of the current position to the first element; otherwise, it advances
  // the value of the current position to the next element.
}

Now what I need help in figuring out is how to implement a RefSortedList, and adding the car part info to it! for each car part, there will be a ID#, Name, Stock and price for example(ID# 001, Name Alternator, Stock 14 [units], Price $45.99)! And each car part with 4 different items should only take up one node in the linked list. Can anyone help me?

[AZRebelCowgirl73]

I figured in simple terms my best bet was to start with a simple adding of a carPart and then trying to print it, here is that section. I have not implemented anything else yet, figured it would be easier to see if the linked list was populating first! However, what is happening when I try to print it out is this it says

List:
CarPart@69b332

and I cant figure out how to fix this! i am assuming it is adding the carpart because if I dont add one then it comes back as:

List:

Here is what I got so far! Changes at Lines (49-63 and 70-73)!!!!!

import java.util.*;
import java.lang.*;
import java.io.*;
import ch06.lists.*;
 
public class UIandDB {
 
    public static void main (String [] args) throws IOException {
 
      Scanner stdin = new Scanner(System.in);
 
      System.out.println("Car Part Database");
 
      //use a RefSortedList (line29)
      SortedListInterface carParts = new ArraySortedList(20);
 
      String skip;            //skip end of line after reading an integer
      boolean keepGoing;      //flag for "choose operation" loop
      int operation;            //indicates user's choice of operations
 
      keepGoing = true;
      while (keepGoing) {
          System.out.println("Choose and Operation:");
          //insert command
          System.out.println("1: Add new car part to the database");
          //delete command
          System.out.println("2: Remove a car part from the database");
          //print all parts command
          System.out.println("3: Print all car parts currently in the database");
          //print a part command
          System.out.println("4: Print a particular car part currently in the database");
          //increase part stock command
          System.out.println("5: Increase current stock level for a car part in the database");
          //deliver part command
          System.out.println("6: Deliver a certain amount of a car part in the database to a customer");
          //exit command (line50)
          System.out.println("7: Exit the car part database");
          if (stdin.hasNextInt()) {
            operation = stdin.nextInt();
          }
          else {
            System.out.println("Error: you must enter a number between 1 and 7!");
            System.out.println("Terminating Database!");
            return;
          }
          skip = stdin.nextLine();
 
          switch (operation) {
                case 1: //insert command (line62)
            //adds new part type to database(partID, partName, partStock, and partPrice)
            //inputted by user
            System.out.println("Please enter the following:");
            System.out.print("Part ID#: ");
            int ID = stdin.nextInt();
            System.out.print("Part Name: ");
            String n = stdin.next();
            System.out.print("Total " + n + "'s to be added to database:");
            int s = stdin.nextInt();
            System.out.print("Price of each " + n + ": $");
            double p = stdin.nextDouble();
            CarPart carPart = new CarPart(ID, n, s, p);
            carParts.add(carPart);
            break;
 
            case 2: //delete command
            //removes a part from the database(part is no longer produced by the company)
            //user inputs partID of the part and it is removed from the database
              break;
 
            case 3: //print all parts command
            //displays on screen all parts in the database
            System.out.println(carParts);
            break;
 
            case 4: //print a part command
            //displays on screen data about a specified car part
            //user inputs partID of the part and it is displayed
            break;
 
            case 5: //increase part stock command
            //increase the available stock of a certain part
            //user inputs partID and quantity to be added to existing part stock
            break;
 
            case 6: //deliver part command
            //deliver a specified quantity of a certain part to customer
            //user inputs partID and the quantity to be delivered
            break;
 
            case 7: //exit command
            //exit the application
            keepGoing = false;
            break;
         }
      }
    System.out.println("Closing the car part database.");
    System.out.println("Thanks for using my program!");
    }
}

[AZRebelCowgirl73]

Ok I have made quite a few changes. Here are my new problems!!!

Cases 1, 2, 3, and 7 all work properly! I can not get case 4 to work right! I have not attempted 5 or 6 yet, but I have made alot of changes so here are both files now partially working.

import java.util.*;
import java.net.*;
import java.lang.*;
import support.*;
 
public class CarPart implements Comparable {
 
    public int partID;
    public String partName;
    public int partStock;
    public double partPrice;
 
    //constructor with parameters
    public CarPart(int ID, String n, int s, double p) {
        partID = ID;
        partName = n;
        partStock = s;
        partPrice = p;
    }//end constructor
 
    //(part ID accessor)
    public int getPartID() {
        return partID;
    }//end method
 
    //(part name accessor)
    public String getPartName() {
        return partName;
    }//end method
 
    //(part stock accessor)
    public int getStock() {
        return partStock;
    }//end method
 
    //(part price accessor)
    public double getPartPrice() {
        return partPrice;
    }//end method
 
    //(transformer method)
    public void addToStock(int add) {
        partStock += add;
    }//end method
 
    //(transformer method)
    public boolean removeFromStock(int remove) {
        if ( remove <= partStock){
            partStock -= remove;
            return true;
        } 
        else {
            return false;
        }
    }//end method
 
    //print method
    public void print() {
        System.out.println(getPartID() + ", " + getPartName() + ", " +  getStock() + ", $"+  getPartPrice());
    }//end method 
 
    //toString method
    public String toString() {
        return (partID + ", " + partName + ", " + partStock + ", " + partPrice);
    }//end method
 
    //compareTo method
    public int compareTo(Object o) { 
        // ... method implementation
        if (partID < ((CarPart)o).partID)
            return -1;
        else if (partID == ((CarPart)o).partID)
            return 0;
        else
            return +1;
    }//end method
 
    //equals method
    public boolean equals(Object o) {
        if(partID == ((CarPart)o).getPartID()) return true;
        else return false;
    }//end method
}

public class UIandDB {
 
    public static void main (String [] args) throws IOException {
 
    Scanner stdin = new Scanner(System.in);
 
    System.out.println("Car Part Database");
    System.out.println("");
 
    //use a RefSortedList (line29)
    SortedListInterface carParts = new ArraySortedList();
 
    String skip;        //skip end of line after reading an integer
    boolean keepGoing;    //flag for "choose operation" loop
    int operation;        //indicates user's choice of operations
 
    keepGoing = true;
    while (keepGoing) {
        System.out.println("Choose an Operation:");
        //insert command
        System.out.println("1: Add new car part to the database");
        //delete command
        System.out.println("2: Remove a car part from the database");
        //print all parts command
        System.out.println("3: Print all car parts in the database");
        //print a part command
        System.out.println("4: Print a car part in the database");
        //increase part stock command
        System.out.println("5: Increase current stock level for a car part");
        //deliver part command
        System.out.println("6: Deliver a certain amount of a car part to a customer");
        //exit command (line50)
        System.out.println("7: Exit the car part database");
        System.out.print("Choice: (1-7): ");
        if (stdin.hasNextInt()) {
        operation = stdin.nextInt();
        }
        else {
        System.out.println("Error: you must enter a number between 1 and 7!");
        System.out.println("Terminating Database!");
        return;
        }
        skip = stdin.nextLine();
 
        switch (operation) {
            case 1: //insert command (line62)
        //adds new part type to database(partID, partName, partStock, and partPrice)
        //inputted by user
        System.out.println("");
        System.out.println("Add a new Car Part:");
        System.out.println("-------------------");
        System.out.print("Car Part ID#: ");
        int ID = stdin.nextInt();
        System.out.print("Car Part Name: ");
        String n = stdin.next();
        System.out.print("Total # of " + n + "'s to be added:");
        int s = stdin.nextInt();
        System.out.print("Total Price of each " + n + ": $");
        double p = stdin.nextDouble();
        CarPart carPart = new CarPart(ID, n, s, p);
        carParts.add(carPart);
        System.out.println("");        
        break;
 
        case 2: //delete command
        //removes a part from the database(part is no longer produced by the company)
        //user inputs partID of the part and it is removed from the database
        System.out.println("");
        System.out.println("Remove a Car Part:");
        System.out.println("------------------");
        System.out.print("partID# of the car part you would like to remove? ");
        int removeID = stdin.nextInt();
        CarPart dummy = new CarPart(removeID, "", 0, 0.0);
        carParts.remove(dummy);
        System.out.println("");
            break;
 
        case 3: //print all parts command
        //displays on screen all parts in the database
        System.out.println("");
        System.out.println("Print all Car Parts:");
        System.out.println("--------------------");
        System.out.print("Sorted ");
        System.out.println(carParts);
        System.out.println("");
        break;
 
        case 4: //print a car part command
        //displays on screen data about a specified car part
        //user inputs partID of the part and it is displayed
        System.out.println("");
        System.out.print("What partID would you like displayed?");
        int partPrint = stdin.nextInt();
        carParts.get(partPrint);
        break;
 
        case 5: //increase part stock command
        //increase the available stock of a certain part
        //user inputs partID and quantity to be added to existing part stock
        break;
 
        case 6: //deliver part command
        //deliver a specified quantity of a certain part to customer
        //user inputs partID and the quantity to be delivered
        break;
 
        case 7: //exit command
        //exit the application
        keepGoing = false;
        break;
       }
    }
    System.out.println("");
    System.out.println("Closing the car part database.");
    System.out.println("Thanks for using my program!");
    }
}

[JoeMac3313]

I am having the same problem

[JosAH]

Now what I need help in figuring out is how to implement a RefSortedList, and adding the car part info to it! for each car part, there will be a ID#, Name, Stock and price for example(ID# 001, Name Alternator, Stock 14 [units], Price $45.99)! And each car part with 4 different items should only take up one node in the linked list. Can anyone help me?

That RefSortedList already is implemented, see the code you posted in your
own thread. If you'd read the add() method implementation you'd noticed that
it takes a Comparable as a parameter.

You want to add CarParts to that list so your CarPart class should implement
the Comparable interface; all for obvious reasons: the RefSortedList tries to
keep the list sorted so it should be able to determine if a < b, a == b or a > b.
The Comparable interface takes care of that.

Read the API documentation for that interface.

kind regards,

Jos

[AZRebelCowgirl73]

I altered case 4 and it is now working!

I now have a delima with case 5!!!!! Here is what I have done so far!

case 5: //increase part stock command
        //increase the available stock of a certain part
        //user inputs partID and quantity to be added to existing part stock
        System.out.print("What partID would you like to add stock too? ");
        int incPart = stdin.nextInt();
        System.out.print("How much stock would you like to add to part # " + incPart + "? ");
        int increaseStock = stdin.nextInt();
        System.out.println("");
        CarPart dummy3 = new CarPart(incPart, "", 0, 0.0);
        carParts.get(dummy3);
        CarPart.addToStock(increaseStock);
        System.out.println(carParts.get(dummy3));
        break;

However whenever I try to compile UIandDB.java i get the following error! (pulling hair out)!!!!!

UIandDB.java:138: non-static method addToStock(int) cannot be referenced from a static context
CarPart.addToStock(increaseStock);
1 error

[r035198x]

I altered case 4 and it is now working!

I now have a delima with case 5!!!!! Here is what I have done so far!

case 5: //increase part stock command
        //increase the available stock of a certain part
        //user inputs partID and quantity to be added to existing part stock
        System.out.print("What partID would you like to add stock too? ");
        int incPart = stdin.nextInt();
        System.out.print("How much stock would you like to add to part # " + incPart + "? ");
        int increaseStock = stdin.nextInt();
        System.out.println("");
        CarPart dummy3 = new CarPart(incPart, "", 0, 0.0);
        carParts.get(dummy3);
        CarPart.addToStock(increaseStock);
        System.out.println(carParts.get(dummy3));
        break;

However whenever I try to compile UIandDB.java i get the following error! (pulling hair out)!!!!!

UIandDB.java:138: non-static method addToStock(int) cannot be referenced from a static context
CarPart.addToStock(increaseStock);
1 error

Don't just say CarPart.addToStock. Call the addToStock method on a particular CarPart object. otherwise you'd need to make the addToStock method static as well.

[AZRebelCowgirl73]

I tried dummy3.addToStock(increaseStock) but it doesnt work!

Here is what I am now trying!

case 5: //increase part stock command
        //increase the available stock of a certain part
        //user inputs partID and quantity to be added to existing part stock
        System.out.print("What partID would you like to add stock too? ");
        int incPart = stdin.nextInt();
        System.out.print("How much stock would you like to add to part # " + incPart + "? ");
        int increaseStock = stdin.nextInt();
        System.out.println("");
        CarPart dummy3 = new CarPart(incPart, "", 0, 0.0);
        carParts.get(dummy3);
        System.out.println(carParts.get(dummy3));
        dummy3.getStock();
        dummy3.addToStock(increaseStock);
        carParts.remove(dummy3);
        carParts.add(dummy3);
        System.out.println(carParts.get(dummy3));
        break;

When I attempt this I get the following!

If I tell the program i want to add stock to partID 123 and I want to add 10 units, this is what I get!
the first print comes out right but the second i believe is only referencing the change because it prints like this
ID#:123, Name: qwe, Quantity: 23, Price: $23.0
ID#: 123, Name: , Quantity: 10, Price: $0.0
I am losing the origanal values!

[r035198x]

I tried dummy3.addToStock(increaseStock) but it doesnt work!

What does it do or not do when you use dummy3?

[AZRebelCowgirl73]

I tried dummy3.addToStock(increaseStock) but it doesnt work!

Here is what I am now trying!

case 5: //increase part stock command
        //increase the available stock of a certain part
        //user inputs partID and quantity to be added to existing part stock
        System.out.print("What partID would you like to add stock too? ");
        int incPart = stdin.nextInt();
        System.out.print("How much stock would you like to add to part # " + incPart + "? ");
        int increaseStock = stdin.nextInt();
        System.out.println("");
        CarPart dummy3 = new CarPart(incPart, "", 0, 0.0);
        carParts.get(dummy3);
        System.out.println(carParts.get(dummy3));
        dummy3.getStock();
        dummy3.addToStock(increaseStock);
        carParts.remove(dummy3);
        carParts.add(dummy3);
        System.out.println(carParts.get(dummy3));
        break;

When I attempt this I get the following!

If I tell the program i want to add stock to partID 123 and I want to add 10 units, this is what I get!
the first print comes out right but the second i believe is only referencing the change because it prints like this
ID#:123, Name: qwe, Quantity: 23, Price: $23.0
ID#: 123, Name: , Quantity: 10, Price: $0.0
I am losing the origanal values!

[mingster]

I tried dummy3.addToStock(increaseStock) but it doesnt work!

Here is what I am now trying!

case 5: //increase part stock command
        //increase the available stock of a certain part
        //user inputs partID and quantity to be added to existing part stock
        System.out.print("What partID would you like to add stock too? ");
        int incPart = stdin.nextInt();
        System.out.print("How much stock would you like to add to part # " + incPart + "? ");
        int increaseStock = stdin.nextInt();
        System.out.println("");
        CarPart dummy3 = new CarPart(incPart, "", 0, 0.0);
        carParts.get(dummy3);
        System.out.println(carParts.get(dummy3));
        dummy3.getStock();
        dummy3.addToStock(increaseStock);
        carParts.remove(dummy3);
        carParts.add(dummy3);
        System.out.println(carParts.get(dummy3));
        break;

When I attempt this I get the following!

If I tell the program i want to add stock to partID 123 and I want to add 10 units, this is what I get!
the first print comes out right but the second i believe is only referencing the change because it prints like this
ID#:123, Name: qwe, Quantity: 23, Price: $23.0
ID#: 123, Name: , Quantity: 10, Price: $0.0
I am losing the origanal values!

How did you alter 4, Ive been stuck on 4 for a bit now.