import java.util.ArrayList; 
import java.util.List;
import javax.swing.*; 
import java.awt.*; 
import java.awt.event.*;


class ShoppingListModel {
    private final List<String> shoppingList = new ArrayList<>();

    public void addItem(String item) {
        shoppingList.add(item); 
    }

    public List<String> getShoppingList() {
        return shoppingList;
    }
}
class ShoppingListView {

    private ShoppingListController controller = null;
    private final DefaultListModel<String> shoppingList;
    private final JTextField inputField;
    private final JList<String> itemList;


    public ShoppingListView() {
        try {
            UIManager.setLookAndFeel(UIManager.getCrossPlatformLookAndFeelClassName());
        } catch (Exception e) { System.exit(1); }


        shoppingList = new DefaultListModel<>();


        JFrame frame = new JFrame("Shopping List");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);


        inputField = new JTextField(20);
        JButton addButton = new JButton("Add");


        addButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                controller.addItem(inputField.getText());
                inputField.setText("");
                inputField.requestFocusInWindow();
            }
        });


        itemList = new JList<>(shoppingList);
        JScrollPane scrollPane = new JScrollPane(itemList);


        JPanel panel = new JPanel(new BorderLayout());
        panel.add(inputField, BorderLayout.NORTH);
        panel.add(addButton, BorderLayout.CENTER);
        panel.add(scrollPane, BorderLayout.SOUTH);


        frame.add(panel);
        frame.pack(); frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    public void updateItemListView(List<String> items) {
        shoppingList.clear();
        for(String item : items) {
            shoppingList.addElement(item);
        }
    }


    public void setController(ShoppingListController controller) {
        this.controller = controller;
    }
}


class ShoppingListController {
    private final ShoppingListModel model;
    private final ShoppingListView view;


    public ShoppingListController(ShoppingListModel model, ShoppingListView view) {
        this.model = model;
        this.view = view;
    }


    public void addItem(String item) {
        if (item != null && !item.strip().isEmpty()) {
            model.addItem(item.strip());
            updateView();
        }
    }


    private void updateView() {
        List<String> shoppingList = model.getShoppingList();
        view.updateItemListView(shoppingList);
    }
}


class ShoppingListApp {
    public static void main(String[] args) {
            ShoppingListModel model = new ShoppingListModel();
            ShoppingListView view = new ShoppingListView();
            ShoppingListController controller = new ShoppingListController(model, view);
            view.setController(controller);
    }
}