[FIXED] ArrayList is only copying last value from a delimiter file

Issue

I have a library program that adds values into an array list, writes the lists to a delimited file. When my array list is getting populated, it only copies the last values. Here's the code I have right now:

// LibraryGUI.java file
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Alert;
import javafx.scene.control.Button;
import javafx.scene.control.ListView;
import javafx.scene.control.TextInputDialog;
import javafx.scene.control.Alert.AlertType;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.HBox;
import javafx.stage.Stage;
import java.util.Optional;
import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.collections.ListChangeListener;
import javafx.collections.ObservableList;



public class LibraryGUI extends Application {

   private Library library = new Library(this);
   private static Button btAddItem = new Button("Add");
   private static Button btCheckOut = new Button("Check Out");
   private static Button btCheckIn = new Button("Check In");
   private static Button btDelete = new Button("Delete");
   private ListView<String> list;

   @Override
   public void start(Stage primaryStage) throws Exception {
       HBox buttonPanel = new HBox();
       buttonPanel.getChildren().addAll(btAddItem, btCheckOut, btCheckIn, btDelete);
       buttonPanel.setAlignment(Pos.CENTER);
       buttonPanel.setSpacing(17);

       list = new ListView<String>();
       list.setEditable(true);
       ObservableList<String> allItems = FXCollections.observableArrayList(library.listAllItems());
       list.setItems(allItems);
       allItems.addListener((ListChangeListener<Object>) change -> {
           System.out.println("List View Changed");
       });

       BorderPane bPane = new BorderPane();
       BorderPane.setAlignment(list, Pos.TOP_LEFT);
       BorderPane.setMargin(list, new Insets(14,14,8,14));
       BorderPane.setMargin(buttonPanel, new Insets(0,8,8,8));
       bPane.setCenter(list);
       bPane.setBottom(buttonPanel);

       // Add Item Button action
       btAddItem.setOnAction(e -> {
           addNewItem();
           list.setItems(FXCollections.observableArrayList(library.listAllItems())); // Update GUI
       });
       // Check Out Item Button action
       btCheckOut.setOnAction(e -> {
           checkOutItem();
           list.setItems(FXCollections.observableArrayList(library.listAllItems())); // Update GUI
       });
       // Check In Item Button action
       btCheckIn.setOnAction(e -> {
           checkInItem();
           list.setItems(FXCollections.observableArrayList(library.listAllItems())); // Update GUI
       });
       // Delete Item Button action
       btDelete.setOnAction(e -> {
           deleteItem();
           list.setItems(FXCollections.observableArrayList(library.listAllItems())); // Update GUI
       });

       Scene scene = new Scene(bPane, 600, 600);
       primaryStage.setTitle("Lending Library");
       primaryStage.setScene(scene);
       primaryStage.setWidth(bPane.getWidth());
       primaryStage.setHeight(bPane.getHeight());
       primaryStage.setResizable(false);
       primaryStage.show();
       // Save on close
       primaryStage.setOnCloseRequest(e -> {
           try {
               library.save();
           } catch (Exception exp) {
               System.out.println("File did not save!");
           } finally {
               System.exit(0);
           }
       });

   }

   // Method to add an item in the list
   public void addNewItem() {

       String name = null, format = null;
       TextInputDialog dialogBox = new TextInputDialog();
       dialogBox.setTitle("Add Item");
       dialogBox.setHeaderText(null);
       dialogBox.setContentText("Name of Item:");
       Optional<String> input = dialogBox.showAndWait();
       if (input.isPresent()) {
           name = input.get();
       }

       dialogBox.getEditor().clear();
       dialogBox.setContentText("FormatType: ");
       input = dialogBox.showAndWait();
       if (input.isPresent()) {
           format = input.get();
       }
       library.addNewItem(name, format);

       try {
        library.save();
       } catch (Exception exc) {
           System.out.println("File did not save!");
           exc.printStackTrace();
       }
   }

   // Method to delete an item in the list
   public void deleteItem() {
       Object selected = list.getSelectionModel().getSelectedItem();
       String s = selected.toString();
       String title = s.substring(0, s.lastIndexOf("("));
       title = title.trim();
       library.delete(title);

       try {
        library.save();
        } catch (Exception exc) {
           System.out.println("File did not save!");
           exc.printStackTrace();
           }
   }

   // Method to check out item in the list
   public void checkOutItem() {
       String name = null, 
               date = null;

       TextInputDialog dialogBox = new TextInputDialog();
       dialogBox.setTitle("Item Check Out");
       dialogBox.setHeaderText(null);

       dialogBox.setContentText("Enter Person Loaning To: ");
       Optional<String> result = dialogBox.showAndWait();
       if (result.isPresent()) {
           name = result.get();
       }

       dialogBox.getEditor().clear();
       dialogBox.setContentText("Date: ");
       result = dialogBox.showAndWait();
       if (result.isPresent()) {
           date = result.get();
       }

       try {
           library.markItemOnLoan(list.getSelectionModel().getSelectedIndex(), name, date);
       } catch (Exception e) {
           Alert alert = new Alert(AlertType.ERROR);
           alert.setTitle("Error");
           alert.setHeaderText(null);
           alert.setContentText(e.getMessage());
       }
   }

   // Method to check in items in the list
   public void checkInItem() {
       Object selected = list.getSelectionModel().getSelectedItem(); // gets the selected item
       String s = selected.toString(); // converts that to a String
       String title = s.substring(0, s.lastIndexOf("(")); // extracts the title
       title.trim(); // removes any trailing whitespace

       TextInputDialog dialog = new TextInputDialog();
       dialog.setTitle("Item Check In");
       dialog.setHeaderText(null);
       dialog.setContentText("Enter Title Returned: ");

       try {
           library.markItemReturned(list.getSelectionModel().getSelectedIndex());
       } catch (Exception e) {
           Alert alert = new Alert(AlertType.ERROR);
           alert.setTitle("Error");
           alert.setHeaderText(null);
           alert.setContentText(e.getMessage());
       }
   }

   // Method to start GUI
   public static void main(String[] args) {
       Application.launch(args);
   }
}

This is my Library.java file

import java.util.ArrayList;
import java.util.Iterator;
import java.util.Scanner;
import java.io.File;
import java.io.PrintWriter;

public class Library {

   private ArrayList<MediaItem> items;
   private LibraryGUI gui;
   private ArrayList<String> masterList;

   public Library(LibraryGUI GUI) {
       this.gui = gui;
       items = new ArrayList<MediaItem>();
       try {
           open();
       } catch (Exception exp) {
           System.out.println(exp.getMessage());
           exp.printStackTrace();
       }
   }

   // Method to add new item
   public void addNewItem(String title, String format) {
       items.add(new MediaItem(title, format));
       System.out.println("Item Added");
       System.out.println(items.get(items.size() - 1).getTitle());
   }

   // Method to mark item on loan
   public void markItemOnLoan(int index, String title, String loanDate) throws Exception {
       try {
           items.get(index).markOnLoan(title, loanDate);
       } catch (Exception e) {
           throw e;
       }
       return;
   }

   // 
   public ArrayList<String> listAllItems() {
       System.out.println("\nItems Updated~");
       masterList = new ArrayList<String>();

       System.out.println("Number of values in Items: "+ items.size()); // Debugging console output

       for (int index = 0; index < (items.size()); index++) {
           System.out.println("Index for showing Array list: " + index); // Debugging console output

           String mItem = "";
           mItem = items.get(index).getTitle();

           System.out.println(items.get(index).getTitle()); // Debugging console output
           mItem += " (";
           mItem += items.get(index).getFormat();
           mItem += ")";
           if (items.get(index).isOnLoan()) {
               mItem += (" loaned to " + items.get(index).getLoanedTo() + " on " + items.get(index).getDateLoaned());
           }
           masterList.add(mItem);
           System.out.println("Number of items in Master List: "+ masterList.size()); // Debugging console output
           System.out.println("Added " + items.get(index).getTitle()); // Debugging console output
       }

       return masterList;
   }

   // Method to mark item returned
   public void markItemReturned(int index) {
       try {
           items.get(index).markReturned();
       } catch (Exception e) {
           e.printStackTrace();
       }
       return;
   }

   // Method to delete item
   public void delete(String title) {

       Iterator<MediaItem> iter = items.iterator();
       while (iter.hasNext()) {
            MediaItem mItem = iter.next();
            if(mItem.getTitle().equalsIgnoreCase(title))
                iter.remove();
       }

   }

   // Method to save items to file
   public void save() throws Exception {
       File file = new File("libraryItems.txt");
       PrintWriter pw = new PrintWriter(file);

       for(MediaItem item : items) {
           pw.println(
                   "%" + item.getTitle() + "%" + item.getFormat() + "%" + item.isOnLoan() + 
                   "%" + (item.isOnLoan() ? item.getLoanedTo() : "null") + "%" + 
                           (item.isOnLoan() ? item.getDateLoaned() : "null"));
       }

       System.out.println("File Saved");
       pw.close();
   }

   // Method to open file
   public void open() throws Exception {
       MediaItem mItem = new MediaItem();
       String itemStr;
       String loanedTo;
       Scanner fileInput = new Scanner(new File("libraryItems.txt"));
       fileInput.useDelimiter("%");

       while (fileInput.hasNext()) {
           System.out.println("File opened!"); // Debugging console output
           mItem.setTitle(fileInput.next());
           mItem.setFormat(fileInput.next());
           mItem.setOnLoan(fileInput.nextBoolean());
           loanedTo = fileInput.next();
           mItem.setLoanedTo(loanedTo != "null" ? loanedTo: null);
           itemStr = fileInput.next();
           mItem.setDateLoaned(itemStr != "null" ? itemStr : null);
           System.out.println(mItem.getTitle() + " (" + mItem.getFormat() + ") " + mItem.isOnLoan() + 
                   " " + (mItem.isOnLoan() ? mItem.getLoanedTo() : "null") + " "  + 
                   (mItem.isOnLoan() ? mItem.getDateLoaned() : "null")); // Debugging console output

           items.add(mItem);

           System.out.println("Item added: " + mItem.getTitle()); // Debugging console output
           System.out.println("Number of values in Item: " + items.size()); // Debugging console output
       }
       System.out.println("Number of values in Item: " + items.size()); // Debugging console output
       fileInput.close();
   }
}

This is my MediaItem.java file

public class MediaItem {
    private String title;
    private String format;
    private boolean onLoan;
    private String dateLoaned;
    private String loanedTo;

    public MediaItem() {
        title = null;
        format = null;
        onLoan = false;
        dateLoaned = null;
        loanedTo = null;
    }

    public MediaItem(String title, String format){
        this.title = title;
        this.format = format;
        this.onLoan = false;
        this.dateLoaned = null;
        this.loanedTo = null;
    }

    public void markOnLoan(String name, String date){
        if(onLoan)
            System.out.println("This title is already loaned to " + loanedTo + " on " + dateLoaned);
        else {
            this.loanedTo = name;
            this.dateLoaned = date;
            this.onLoan = true;
            }
        }

    public void markReturned() {
        if(!onLoan) {
            System.out.println("This title is not currently loaned out");
        }else
        {
            this.onLoan = false;
            this.loanedTo = null;
            this.dateLoaned = null;
        }
    }

    public String getTitle() {
        return title;
        }
    public void setTitle(String title) {
        this.title = title;
        }
    public String getFormat() {
        return format;
        }
    public void setFormat(String format) {
        this.format = format;
        }
    public boolean isOnLoan() {
        return onLoan;
        }
    public void setOnLoan(boolean onLoan) {
        this.onLoan = onLoan;
        }
    public String getDateLoaned() {
        return dateLoaned;
        }
    public void setDateLoaned(String dateLoaned) {
        this.dateLoaned = dateLoaned;
        }
    public String getLoanedTo() {
        return loanedTo;
        }
    public void setLoanedTo(String loanedTo) {
        this.loanedTo = loanedTo;
        }
    }

And this is a sample libraryItems.txt file

%one%DVD%false%null%null
%two%DVD%false%null%null
%three%DVD%false%null%null

From my 'debugging' console output I can tell that in the "public ArrayList listAllItems" method is when the problem is occurring, but I'm not sure why. I have looked at similar questions and they don't seem to be working! A nudge in the right direction is appreciated!

Solution

Your code for item creation resides outside the while loop in open(). This results in only one instance per call being created. This instance is repeatedly updated.

You need to move the item creation inside the loop body:

   public void open() throws Exception {

       try (Scanner fileInput = new Scanner(new File("libraryItems.txt"))) { // try-with resources makes sure that the Scanner is closed even on an error

          fileInput.useDelimiter("%");

          System.out.println("File opened!"); // Debugging console output

           while (fileInput.hasNext()) {
               MediaItem mItem = new MediaItem(); // create one item per line
               mItem.setTitle(fileInput.next());
               mItem.setFormat(fileInput.next());
               mItem.setOnLoan(fileInput.nextBoolean());

               String loanedTo = fileInput.next();
               mItem.setLoanedTo(loanedTo != "null" ? loanedTo: null);

               String itemStr = fileInput.next();
               mItem.setDateLoaned(itemStr != "null" ? itemStr : null);

               System.out.println(mItem.getTitle() + " (" + mItem.getFormat() + ") " + mItem.isOnLoan() + 
                       " " + (mItem.isOnLoan() ? mItem.getLoanedTo() : "null") + " "  + 
                       (mItem.isOnLoan() ? mItem.getDateLoaned() : "null")); // Debugging console output

               items.add(mItem);

               System.out.println("Item added: " + mItem.getTitle()); // Debugging console output
               System.out.println("Number of values in Item: " + items.size()); // Debugging console output
           }
           System.out.println("Number of values in Item: " + items.size()); // Debugging console output
       }
   }

Answered By - fabian