困惑内心类，简单的行动

Question

我有一个简单的表单设置，我正在按照本书Core Java Vol I设置表单的方式，他们有一个顶级类，扩展JFrame创建不同组件的对象，并将它们放在帧。如果这不是您“通常”应该这样做的方式，请告诉我。

当我编写内部类以按下按钮时执行操作时，我感到很困惑。我可以把我的内部类放在我的AddressBookForm类中，因为那是我放置按钮的地方，它可以访问JTextFields的私有变量。我有这个问题（假设到目前为止其他部分都是'ok'），我不知道如何获取addressList.size（）所以我可以用插入按钮时的总人数更新我的statusBar标签按下。有什么想法吗？感谢。

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

public class AddressBook
{
    public static void main(String[] args)
    {
        EventQueue.invokeLater(new Runnable()
        {
            public void run()
            {
                AddressBookFrame frame = new AddressBookFrame();
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

                JMenuBar menuBar = new JMenuBar();
                frame.setJMenuBar(menuBar);

                JMenu fileMenu = new JMenu("File");
                JMenuItem openItem = new JMenuItem("Open");
                JMenuItem saveItem = new JMenuItem("Save");
                JMenuItem saveAsItem = new JMenuItem("Save As");
                JMenuItem printItem = new JMenuItem("Print");
                JMenuItem exitItem = new JMenuItem("Exit");
                fileMenu.add(openItem);
                fileMenu.add(saveItem);
                fileMenu.add(saveAsItem);
                fileMenu.add(printItem);
                fileMenu.add(exitItem);
                menuBar.add(fileMenu);

                JMenu editMenu = new JMenu("Edit");
                JMenuItem newItem = new JMenuItem("New");
                JMenuItem editItem = new JMenuItem("Edit");
                JMenuItem deleteItem = new JMenuItem("Delete");
                JMenuItem findItem = new JMenuItem("Find");
                JMenuItem firstItem = new JMenuItem("First");
                JMenuItem previousItem = new JMenuItem("Previous");
                JMenuItem nextItem = new JMenuItem("Next");
                JMenuItem lastItem = new JMenuItem("Last");
                editMenu.add(newItem);
                editMenu.add(editItem);
                editMenu.add(deleteItem);
                editMenu.add(findItem);
                editMenu.add(firstItem);
                editMenu.add(previousItem);
                editMenu.add(nextItem);
                editMenu.add(lastItem);
                menuBar.add(editMenu);

                JMenu helpMenu = new JMenu("Help");
                JMenuItem documentationItem = new JMenuItem("Documentation");
                JMenuItem aboutItem = new JMenuItem("About");
                helpMenu.add(documentationItem);
                helpMenu.add(aboutItem);

                menuBar.add(helpMenu);

                frame.setVisible(true);

            }
        });
    }
}

class AddressBookFrame extends JFrame
{
    public AddressBookFrame() 
    {
        setLayout(new BorderLayout());
        setTitle("Address Book");
        setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
        AddressBookToolBar toolBar = new AddressBookToolBar();
        add(toolBar, BorderLayout.NORTH);
        AddressBookStatusBar aStatusBar = new AddressBookStatusBar();
        add(aStatusBar, BorderLayout.SOUTH);
        AddressBookForm form = new AddressBookForm();
        add(form, BorderLayout.CENTER);
    }
    public static final int DEFAULT_WIDTH = 500;
    public static final int DEFAULT_HEIGHT = 500;

}

/* Create toolbar buttons and add buttons to toolbar */
class AddressBookToolBar extends JPanel
{
    public AddressBookToolBar()
    {
        setLayout(new FlowLayout(FlowLayout.LEFT));
        JToolBar bar = new JToolBar();
        JButton newButton = new JButton("New");
        JButton editButton = new JButton("Edit");
        JButton deleteButton = new JButton("Delete");
        JButton findButton = new JButton("Find");
        JButton firstButton = new JButton("First");
        JButton previousButton = new JButton("Previous");
        JButton nextButton = new JButton("Next");
        JButton lastButton = new JButton("Last");
        bar.add(newButton);
        bar.add(editButton);
        bar.add(deleteButton);
        bar.add(findButton);
        bar.add(firstButton);
        bar.add(previousButton);
        bar.add(nextButton);
        bar.add(lastButton);
        add(bar);
    }
}

/* Creates the status bar string */
class AddressBookStatusBar extends JPanel
{
    public AddressBookStatusBar()
    {
        setLayout(new FlowLayout(FlowLayout.LEFT));
        this.statusBarString = new JLabel("Total: " + totalContacts);
        add(this.statusBarString);
    }

    public void updateLabel(int n)
    {
        contactsLabel.setText((new Integer(n)).toString());
    }

    private JLabel statusBarString;
    private JLabel contactsLabel;
}

class AddressBookForm extends JPanel
{
    public AddressBookForm()
    {   
        // create form panel
        this.setLayout(new GridLayout(2, 1));
        JPanel formPanel = new JPanel();
        formPanel.setLayout(new GridLayout(4, 2));
        firstName = new JTextField(20);
        lastName = new JTextField(20);
        telephone = new JTextField(20);
        email = new JTextField(20);
        JLabel firstNameLabel = new JLabel("First Name: ", JLabel.LEFT);
        formPanel.add(firstNameLabel);
        formPanel.add(firstName);
        JLabel lastNameLabel = new JLabel("Last Name: ", JLabel.LEFT); 
        formPanel.add(lastNameLabel);
        formPanel.add(lastName);
        JLabel telephoneLabel = new JLabel("Telephone: ", JLabel.LEFT);
        formPanel.add(telephoneLabel);
        formPanel.add(telephone);
        JLabel emailLabel = new JLabel("Email: ", JLabel.LEFT);
        formPanel.add(emailLabel);
        formPanel.add(email);
        add(formPanel);

        // create button panel
        JPanel buttonPanel = new JPanel();
        JButton insertButton = new JButton("Insert");
        JButton displayButton = new JButton("Display");

        ActionListener insertAction = new AddressBookListener();
        ActionListener displayAction = new AddressBookListener();
        insertButton.addActionListener(insertAction);
        displayButton.addActionListener(displayAction);
        buttonPanel.add(insertButton);
        buttonPanel.add(displayButton);
        add(buttonPanel);
    }

    public int getTotalContacts()
    {
        return addressList.size();
    }

    private JTextField firstName;
    private JTextField lastName;
    private JTextField telephone;
    private JTextField email;
    private JLabel contacts;

    private List<Person> addressList = new ArrayList<Person>();

    private class AddressBookListener implements ActionListener
    {
        public void actionPerformed(ActionEvent e)
        {
            String buttonPressed = e.getActionCommand();
            System.out.println(buttonPressed);
            if (buttonPressed == "Insert") {
                Person aPerson = new Person(firstName.getText(), lastName.getText(), telephone.getText(), email.getText());
                addressList.add(aPerson);
            }
            else {
                for (Person p : addressList) {
                    System.out.println(p);
                }
            }
        }
    }

}

Answer 1

不要将组件中的人员列表存储紧密耦合。

有一个提供人员列表的服务类或接口，类似这样的

public interface AddressBookService {

    List<Person> getContacts();

    void addContact(Person contact);

    void deleteContact(Person person);

}

现在，让每个组件都可以通过注入或将其用作单例或任何其他查找方法来访问此服务。

Answer 2

我投票支持seanizer的解决方案，但是如果你坚持使用你的代码，你可以这样使用在其内部类中访问外部类的addressList变量（AddressBookFrame）：

class AddressBookFrame extends JFrame {

private List<Person> addressList = new ArrayList<Person>();

public AddressBookFrame() {
    setLayout(new BorderLayout());
    setTitle("Address Book");
    setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
    AddressBookToolBar toolBar = new AddressBookToolBar();
    add(toolBar, BorderLayout.NORTH);
    AddressBookStatusBar aStatusBar = new AddressBookStatusBar();
    add(aStatusBar, BorderLayout.SOUTH);
    AddressBookForm form = new AddressBookForm();
    add(form, BorderLayout.CENTER);
}

public static final int DEFAULT_WIDTH = 500;
public static final int DEFAULT_HEIGHT = 500;

/* Creates the status bar string */
class AddressBookStatusBar extends JPanel {
    public AddressBookStatusBar() {
        setLayout(new FlowLayout(FlowLayout.LEFT));
        this.statusBarString = new JLabel("Total: " + addressList.size());
        add(this.statusBarString);
    }

    public void updateLabel(int n) {
        contactsLabel.setText((new Integer(n)).toString());
    }

    private JLabel statusBarString;
    private JLabel contactsLabel;
}

/* Create toolbar buttons and add buttons to toolbar */
class AddressBookToolBar extends JPanel {
    public AddressBookToolBar() {
        setLayout(new FlowLayout(FlowLayout.LEFT));
        JToolBar bar = new JToolBar();
        JButton newButton = new JButton("New");
        JButton editButton = new JButton("Edit");
        JButton deleteButton = new JButton("Delete");
        JButton findButton = new JButton("Find");
        JButton firstButton = new JButton("First");
        JButton previousButton = new JButton("Previous");
        JButton nextButton = new JButton("Next");
        JButton lastButton = new JButton("Last");
        bar.add(newButton);
        bar.add(editButton);
        bar.add(deleteButton);
        bar.add(findButton);
        bar.add(firstButton);
        bar.add(previousButton);
        bar.add(nextButton);
        bar.add(lastButton);
        add(bar);
    }
}

class AddressBookForm extends JPanel {
    public AddressBookForm() {
        // create form panel
        this.setLayout(new GridLayout(2, 1));
        JPanel formPanel = new JPanel();
        formPanel.setLayout(new GridLayout(4, 2));
        firstName = new JTextField(20);
        lastName = new JTextField(20);
        telephone = new JTextField(20);
        email = new JTextField(20);
        JLabel firstNameLabel = new JLabel("First Name: ", JLabel.LEFT);
        formPanel.add(firstNameLabel);
        formPanel.add(firstName);
        JLabel lastNameLabel = new JLabel("Last Name: ", JLabel.LEFT);
        formPanel.add(lastNameLabel);
        formPanel.add(lastName);
        JLabel telephoneLabel = new JLabel("Telephone: ", JLabel.LEFT);
        formPanel.add(telephoneLabel);
        formPanel.add(telephone);
        JLabel emailLabel = new JLabel("Email: ", JLabel.LEFT);
        formPanel.add(emailLabel);
        formPanel.add(email);
        add(formPanel);

        // create button panel
        JPanel buttonPanel = new JPanel();
        JButton insertButton = new JButton("Insert");
        JButton displayButton = new JButton("Display");

        ActionListener insertAction = new AddressBookListener();
        ActionListener displayAction = new AddressBookListener();
        insertButton.addActionListener(insertAction);
        displayButton.addActionListener(displayAction);
        buttonPanel.add(insertButton);
        buttonPanel.add(displayButton);
        add(buttonPanel);
    }

    public int getTotalContacts() {
        return addressList.size();
    }

    private JTextField firstName;
    private JTextField lastName;
    private JTextField telephone;
    private JTextField email;
    private JLabel contacts;

    private class AddressBookListener implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            String buttonPressed = e.getActionCommand();
            System.out.println(buttonPressed);
            if (buttonPressed == "Insert") {
                Person aPerson = new Person(firstName.getText(), lastName
                        .getText(), telephone.getText(), email.getText());
                addressList.add(aPerson);
            } else {
                for (Person p : addressList) {
                    System.out.println(p);
                }
            }
        }
    }

}

}