GUI‘简单记事本’

Question

请对代码的所有方面给予反馈，无论是注释、方法的使用、语义或任何可以改进的内容。

在我看来，这段代码完美无缺，所以任何改进建议都会产生影响。

//  Imports packages for AWT, Events, Scanner, File, PrintWriter,
//  exceptions and Swing components.
import java.util.Scanner;
import java.io.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

/**
 * This class extends JFrame to inherit all methods for active use.
 * This class implements the interface ActionListener to handle user actions
 */
public class SchultzTobias extends JFrame implements ActionListener {

    //  Declaring all swing components for access throughout multiple methods
    private         JMenuBar      menuBar;
    private         JTextArea     txtArea;
    private final   JMenu[]       menu = new JMenu[4];
    private final   JMenuItem[]   menuItem = new JMenuItem[7];
    private         JMenu         fontMenu;
    private final   JMenuItem[]   fontItem = new JMenuItem[10];

    /**
     * This constructor initializes all components, sets the workspace
     * preferences and connects everything to the JFrame superclass
     */
    public SchultzTobias() {

        //  Assigns a title to the notepad
        super("Simple Notepad");

        //  Initializes the text area for user input
        txtArea = new JTextArea(24, 54);

        //  Sets formatting to break line at whole words, and adding
        //  some border to the JTextArea.
        txtArea.setLineWrap(true);
        txtArea.setWrapStyleWord(true);
        txtArea.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));

        // If content exceeds size of viewport, make scrolling through the
        // content possible
        JScrollPane scrollPane = new JScrollPane(txtArea);

        //  initializes all menus, menuItems and corresponding key bindings
        initializeMenus();
        initializeKeyBindings();

        //  adding menus and JTextArea to the JFrame
        add(menuBar);
        add(scrollPane, BorderLayout.SOUTH);

        //  Presenting the JFrame, and stating the programs close operation
        setVisible(true);
        pack();
        setDefaultCloseOperation(EXIT_ON_CLOSE);
    }

    /**
     * This method constructs and adds names and actionListener's to
     * JMenu's and JMenuItem's, which are then added to the JMenuBar.
     */
    public void initializeMenus() {

        //  Declaring the menu bar
        menuBar = new JMenuBar();

        //  Assigns names to the main menu and adding them to
        //  actionListener's and the menu bar
        String[] menuNames = {"File", "Edit", "Format", "Help"};

        for (int i = 0; i < menu.length; i++) {
            menu[i] = new JMenu(menuNames[i]);
            menu[i].addActionListener(this);
            menuBar.add(menu[i]);
        }

        //  Assigns names to the menu items and adding them to
        //  actionListener's and the main menu
        String[] itemString = {"Open", "Save", "Exit", "Text Wrap",
                "No Text Wrap", "Clear", "About Simple Notepad"};

        for (int i = 0; i < menuItem.length; i++) {
            menuItem[i] = new JMenuItem(itemString[i]);
            menuItem[i].addActionListener(this);

            if (i < 3)      { menu[0].add(menuItem[i]);} // Adding to 'File'
            else if (i < 5) { menu[1].add(menuItem[i]);} // Adding to 'Edit'
            else if (i < 6) { menu[2].add(menuItem[i]);} // Adding to 'Format'
            else            { menu[3].add(menuItem[i]);} // Adding to 'Help'
        }

        // Initializing the menu for fonts and adding
        // menu items with font sizes
        fontMenu = new JMenu("Font");

        for (int i = 0; i < fontItem.length; i++) {
            fontItem[i] = new JMenuItem(String.valueOf((i + 1) * 2));
            fontItem[i].addActionListener(this);
            fontMenu.add(fontItem[i]);
        }

        //  Adding the 'Font' menu to the 'Edit' menu
        menu[1].add(fontMenu);
    }

    /**
     * This method assigns a mnemonic character for each menu and menuItem.
     * If the program is viewed on a Mac, alt(option) key must be pressed
     * to view the mnemonic icon.
     */
    public void initializeKeyBindings() {

        //  The assignment had mnemonic icons on different indexes in its
        //  presentation. To deliver exactly what the assignment specified,
        //  and to keep the code readable, i wrote each mnemonic statement
        //  separately.
        menu[0].setMnemonic(KeyEvent.VK_F);     //  File
        menu[1].setMnemonic(KeyEvent.VK_E);     //  Edit
        menu[2].setMnemonic(KeyEvent.VK_O);     //  Format
        menu[3].setMnemonic(KeyEvent.VK_H);     //  Help

        menuItem[0].setMnemonic(KeyEvent.VK_O); //  Open
        menuItem[1].setMnemonic(KeyEvent.VK_S); //  Save
        menuItem[2].setMnemonic(KeyEvent.VK_E); //  Exit
        menuItem[3].setMnemonic(KeyEvent.VK_W); //  Text Wrap
        menuItem[4].setMnemonic(KeyEvent.VK_N); //  No Text Wrap
        menuItem[5].setMnemonic(KeyEvent.VK_C); //  Clear
        menuItem[6].setMnemonic(KeyEvent.VK_A); //  About

        fontMenu.setMnemonic(KeyEvent.VK_F);    //  Font
    }

    /**
     * This method prompts user to enter name of file that will be attempted
     * to be opened
     *
     * @exception FileNotFoundException On input error.
     */
    public void openFile() {

        //  Prompts user for the name of the file to read
        String fileOutput = "";
        String fileName = JOptionPane.showInputDialog(txtArea, "Oppgi filnavn");

        //  If the user has typed anything, attempt to open file
        if (fileName != null) {
            try {

                //  Read everything from file until the end-anchor is found: \Z
                Scanner content = new Scanner(new File(fileName));
                content.useDelimiter("\\Z");

                while (content.hasNext()) {
                    fileOutput += content.next();
                }

                //  Store content read from file in text area and close dialog
                //  box.
                txtArea.setText(fileOutput);
                content.close();

                //  If file was not found, print the exception that was thrown
            } catch (FileNotFoundException fnfe) {
                System.out.println("This error was thrown: " + fnfe);
            }
        }
    }

    /**
     * This method  prompts user to enter name of file that will be attempted
     * to be stored
     *
     * @exception IOException On output error.
     */
    public void saveFile() {

        //  Prompts user for the name of the file to be stored
        String fileName = JOptionPane.showInputDialog(txtArea, "Oppgi filnavn");

        //  If user has typed in anything, attempt to save file
        if (fileName != null) {

            //  Copy content from the text area into the file being created
            try {
                PrintWriter content = new PrintWriter(new File(fileName));
                content.write(txtArea.getText());
                content.close();

                //  If there was an error, print the exception
            } catch (IOException ioe) {
                System.out.println("This error was thrown: " + ioe);
            }
        }
    }

    /**
     *  This method prompts user with three options
     *      - Save text area to file through method saveFile()
     *      - Exit the program without storing file
     *      - Go back to superclass JFrame
     *
     * @param clear handles what to do after a user has selected an option.
     *              If clear is true, do not exit program after statement.
     *              If clear is false, exit program after statement.
     */
    public void exitFile(boolean clear) {

        //  Prompts user with options to store file, not to store file or
        int options = JOptionPane.showConfirmDialog(
                txtArea, "Vil du lagre først?");

        //  If user acted on the YES option
        if (options == JOptionPane.YES_OPTION) {
            saveFile();

            // And first acted on the 'Clear' menuItem
            if (clear) {
                txtArea.setText("");

            // And first acted on the 'Exit' menuItem
            } else {
                System.exit(0);
            }
        }

        //  If user acted on the NO option
        else if (options == JOptionPane.NO_OPTION) {

            // And first acted on the 'Clear' menuItem
            if (clear) {
                txtArea.setText("");

            // And first acted on the 'Exit' menuItem
            } else {
                System.exit(0);
            }
        }
    }

    /**
     * This method handles user actions on the menu's
     *
     * @param e handles actionListeners
     */
    @Override
    public void actionPerformed(ActionEvent e) {

        //  Stores a variable with the source of the action event for
        //  readable event handling
        Object source = e.getSource();

        //  Names of menuItems that the user can act on is a comment to its
        //  preceding code
        //  Open:
        if (source == menuItem[0]) {
            openFile();
        }

        //  Save:
        if (source == menuItem[1]) {
            saveFile();
        }

        //  Exit:
        if (source == menuItem[2]) {

            //  Exit's the file directly if JTextArea is empty
            if (txtArea.getText().equals("")){
                System.exit(0);
            }
            else {
                exitFile(false);
            }
        }

        //  Text Wrap:
        if (source == menuItem[3]) {
            txtArea.setLineWrap(true);
            txtArea.setWrapStyleWord(true);
        }

        //  No Text Wrap:
        if (source == menuItem[4]) {
            txtArea.setLineWrap(false);
            txtArea.setWrapStyleWord(false);
        }

        //  Font:
        //  Assigns new font size to match the users size preference entered
        for (int i = 0; i < fontItem.length; i++) {
            if (source == fontItem[i]) {
                txtArea.setFont(new Font("Serif", Font.PLAIN,
                        ((i + 1) * 2)));
            }
        }

        //  Clear:
        //  If there is content in JTextArea, prompt user to save content
        if (source == menuItem[5] && !txtArea.getText().equals("")) {
                exitFile(true);
        }

        //  About:
        if (source == menuItem[6]) {
            JOptionPane.showMessageDialog(txtArea,
                    "Denne applikasjonen er laget av\nTobias Goulden Schultz" +
                            "\n\nDet er en enkel tekstbehandler.");
        }
    }

    /**
     * This method is main, it declares and initializes a new Object of
     * the class SchultzTobias
     */
    public static void main(String[] args) {
        SchultzTobias st = new SchultzTobias();
    }
}

Answer 1

自动资源管理

扫描器是可关闭的，所以您可以使用自动资源：

try (Scanner content = new Scanner(new File(fileName))) {
    ... rest of code goes here, don't need a content.close();
} catch (FileNotFoundException fnfe) {
    System.out.println("This error was thrown: " + fnfe);
}

菜单

有很多实现菜单的选项。使用数组和引用索引来确定它们位于哪个菜单下，并找出选择哪个菜单对于小型应用程序是可行的，但是在您决定重新组织菜单时，它不需要缩放，并且需要多个位置来更改索引引用。

如果使用javax.swing.AbstractAction的子类，则可以将操作的逻辑保持为单独的。另外，稍后还可以将相同的操作添加到菜单项和工具栏中。有关可以放入操作的属性，请参见行动javadoc。您可以使用多个构造函数和帮助方法创建AbstractAction的子类，用于设置和获取描述、图标、助记符等。

注释

您不需要以“这个类.”作为JavaDoc注释的开头。或者“这个方法.”请参阅方法描述以动词短语开头。部分。

有些样板不需要评论。例如，“导入”部分实际上不需要注释。另外，有些评论描述了发生了什么，而不是为什么(例如，“设置格式设置为整个单词的行.”)，您只需有一个注释“”，除非有一行您认为会特别忘记为什么会出现这种情况。

不是什么大问题，但英语中的复数不使用撇号(例如菜单可以是菜单)。

编辑后添加：

可以在保持相同功能的同时缩短exitFile()。您的选项只有YES_OPTION和NO_OPTION，而且它们之间有重复的代码，不管如何，它们都可以执行：

public void exitFile(boolean clear) {

    //  Prompts user with options to store file, not to store file or
    int options = JOptionPane.showConfirmDialog(
            txtArea, "Vil du lagre først?");

    //  If user acted on the YES option
    if (options == JOptionPane.YES_OPTION) {
        saveFile();
    }

    // And first acted on the 'Clear' menuItem
    if (clear) {
        txtArea.setText("");

    // And first acted on the 'Exit' menuItem
    } else {
        System.exit(0);
    }
}

Answer 2

对代码的所有方面给予反馈

因此，这里有一个简短的反馈：

我注意到的东西很少，

• 几乎所有的方法都是公开的(这需要吗？)
• initializeMenus()是从ctor内部调用的，但is不是final
• 类SchultzTobias可以子类(它不是final)
• 大多数方法都可以被重写(当子类.)
• menuItem[3]和menu[2]是什么？(你只有很少的静态菜单项，也许你应该考虑使用mnuItmSave，mnuItmOpen，.(为了更好地阅读)
• exitFile(boolean clear)可以缩短(看看它，里面有重复的代码！)
• exitFile(boolean clear)仅由MenuItem操作调用，而不是在关闭窗口时调用(例如，使用windows X-Button)。
• 在setVisible()中调用ctor可以工作，但这是不寻常的(当子类化时可能是意外的)
• 在出现异常时不关闭Closeables (如：PrintWriter)

干杯!