Question

我是stackoverflow和学习Java的新手。我正在为我在大学的一门课程创建一个应用程序，我们必须创建一个带有菜单栏和工具栏的文本编辑器。我已经能够让菜单栏工作，但工具栏没有显示，即使它没有破坏代码。有谁知道这是怎么回事？

import com.sun.deploy.ui.AboutDialog;
import com.sun.org.apache.bcel.internal.generic.RETURN;
import javafx.scene.control.ToolBar;
import javax.swing.JToolBar;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.print.PageFormat;
import java.awt.print.PrinterException;
import java.awt.print.PrinterJob;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import javax.swing.JOptionPane;
import javax.swing.*;
import javax.swing.border.Border;
import javax.swing.event.UndoableEditEvent;
import javax.swing.event.UndoableEditListener;
import javax.swing.undo.CannotUndoException;
import javax.swing.undo.UndoManager;

@SuppressWarnings("serial")
public class DoesThisWork extends JFrame implements ActionListener {

    public static void main(String[] args) {
        new DoesThisWork();
    }

    //============================================
    // FIELDS
    //============================================

    // Menus
    private JMenu fileMenu;
    private JMenu editMenu;
    private JMenu formatMenu;
    private JMenu helpMenu;
    private JMenuItem newFile, openFile, saveFile, saveAsFile, pageSetup, printFile, exit;
    private JMenuItem undoEdit, redoEdit, selectAll, copy, paste, cut;
    private JMenu fontColor, fontSize;
    private JMenuItem about;
    private JMenuItem subColorRed, subColorBlue, subColorGreen, subColorBlack;
    private JMenuItem subTimes, subArial, subCourier, subVerdana;

    //Toolbar Buttons
    private JButton red;
    private JButton blue;
    private JButton green;
    private JButton black;
//    private JButton newFile, openFile, saveFile, saveAsFile, pageSetup, printFile, exit;
//    private JMenuItem undoEdit, redoEdit, selectAll, copy, paste, cut;
//    private JMenu fontColor, fontSize;
//    private JMenuItem about;
//    private JMenuItem subColorRed, subColorBlue, subColorGreen, subColorBlack;
//    private JMenuItem sub8, sub10, sub12, sub50;


    // Window
    private JFrame editorWindow;

    // Text Area
    private Border textBorder;
    private JScrollPane scroll;
    private JTextArea textArea;
    private Font textFont;

    // Window
    private JFrame window;

    // Printing
    private PrinterJob job;
    public PageFormat format;

    // Is File Saved/Opened
    private boolean opened = false;
    private boolean saved = false;

    // Record Open File for quick saving
    private File openedFile;

    // Undo manager for managing the storage of the undos
    // so that the can be redone if requested
    private UndoManager undo;

    //Toolbar
    private JToolBar toolBar;


    //============================================
    // CONSTRUCTOR
    //============================================

    public DoesThisWork() {
        super("Text Editor");

        // Create Menus
        fileMenu();
        editMenu();
        formatMenu();
        helpMenu();

        // Create Text Area
        createTextArea();

        // Create Undo Manager for managing undo/redo commands
        undoMan();

        // Create Window
        createEditorWindow();

        // Create Toolbar
        createToolBar();


    }

    private JFrame createEditorWindow() {
        editorWindow = new JFrame("Text Editor");
        editorWindow.setVisible(true);
        editorWindow.setExtendedState(Frame.MAXIMIZED_BOTH);
        editorWindow.setDefaultCloseOperation(EXIT_ON_CLOSE);
        // Create Menu Bar
        editorWindow.setJMenuBar(createMenuBar());
        editorWindow.add(scroll, BorderLayout.CENTER);
        editorWindow.pack();
        // Centers application on screen
        editorWindow.setLocationRelativeTo(null);
        // Create ToolBar
        //editorWindow.add(toolBar, BorderLayout.NORTH);


        return editorWindow;
    }

    private JTextArea createTextArea() {
        //textBorder = BorderFactory.createBevelBorder(0, Color.BLACK, Color.BLACK);
        textArea = new JTextArea(30, 50);
        textArea.setEditable(true);
        textArea.setBorder(BorderFactory.createCompoundBorder(textBorder, BorderFactory.createEmptyBorder(2, 5, 0, 0)));

        textFont = new Font("Verdana", 0, 14);
        textArea.setFont(textFont);

        scroll = new JScrollPane(textArea, JScrollPane.VERTICAL_SCROLLBAR_ALWAYS, JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);

        return textArea;
    }

    private JMenuBar createMenuBar() {
        JMenuBar menuBar = new JMenuBar();
        setJMenuBar(menuBar);
        menuBar.add(fileMenu);
        menuBar.add(editMenu);
        menuBar.add(formatMenu);
        menuBar.add(helpMenu);

        return menuBar;
    }

    private JToolBar createToolBar(){

        toolBar = new JToolBar();
        toolBar.setFloatable(true);
        red = new JButton("Red");
        red.setToolTipText("Click here to change font color to Red");
        blue = new JButton("Blue");
        blue.setToolTipText("Click here to change font color to Blue");
        green = new JButton("Green");
        green.setToolTipText("Click here to change font color to Green");
        black = new JButton("Black");
        black.setToolTipText("Click here to change font color to Black");
        //add(toolBar, BorderLayout.SOUTH);

        // Toolbar Color Buttons
        toolBar.add(red);
        toolBar.add(blue);
        toolBar.add(green);
        toolBar.add(black);
        add(toolBar, BorderLayout.WEST);

        //ToolBar tb = new ToolBar();
        toolBar.setVisible(true);


        return toolBar;
    }

    private UndoManager undoMan() {
        // Listener for undo and redo functions to document
        undo = new UndoManager();
        textArea.getDocument().addUndoableEditListener(new UndoableEditListener() {

            @Override
            public void undoableEditHappened(UndoableEditEvent e) {
                undo.addEdit(e.getEdit());
            }
        });

        return undo;
    }

    private void fileMenu() {
        // Create File Menu
        fileMenu = new JMenu("File");
        fileMenu.setMnemonic(KeyEvent.VK_F);
        fileMenu.setPreferredSize(new Dimension(40, 20));

        // Add file menu items
        newFile = new JMenuItem("New");
        newFile.setMnemonic(KeyEvent.VK_N);
        newFile.addActionListener(this);
        newFile.setPreferredSize(new Dimension(100, 20));
        newFile.setEnabled(true);

        openFile = new JMenuItem("Open...");
        openFile.setMnemonic(KeyEvent.VK_O);
        openFile.addActionListener(this);
        openFile.setPreferredSize(new Dimension(100, 20));
        openFile.setEnabled(true);

        saveFile = new JMenuItem("Save");
        saveFile.setMnemonic(KeyEvent.VK_S);
        saveFile.addActionListener(this);
        saveFile.setPreferredSize(new Dimension(100, 20));
        saveFile.setEnabled(true);

        saveAsFile = new JMenuItem("Save As...");
        saveAsFile.setMnemonic(KeyEvent.VK_A);
        saveAsFile.addActionListener(this);
        saveAsFile.setPreferredSize(new Dimension(100, 20));
        saveAsFile.setEnabled(true);

        pageSetup = new JMenuItem("Page Setup...");
        pageSetup.setMnemonic(KeyEvent.VK_U);
        pageSetup.addActionListener(this);
        pageSetup.setPreferredSize(new Dimension(100, 20));
        pageSetup.setEnabled(true);

        printFile = new JMenuItem("Print...");
        printFile.setMnemonic(KeyEvent.VK_P);
        printFile.addActionListener(this);
        printFile.setPreferredSize(new Dimension(100, 20));
        printFile.setEnabled(true);

        exit = new JMenuItem("Exit");
        exit.setMnemonic(KeyEvent.VK_E);
        exit.addActionListener(this);
        exit.setPreferredSize(new Dimension(100, 20));
        exit.setEnabled(true);

        // Add items to menu
        fileMenu.add(newFile);
        fileMenu.add(openFile);
        fileMenu.add(saveFile);
        fileMenu.add(saveAsFile);
        fileMenu.add(pageSetup);
        fileMenu.add(printFile);
        fileMenu.add(exit);
    }

    private void editMenu() {
        editMenu = new JMenu("Edit");
        editMenu.setMnemonic(KeyEvent.VK_E);
        editMenu.setPreferredSize(new Dimension(40, 20));

        // Add file menu items
        undoEdit = new JMenuItem("Undo");
        undoEdit.setMnemonic(KeyEvent.VK_U);
        undoEdit.addActionListener(this);
        undoEdit.setPreferredSize(new Dimension(100, 20));
        undoEdit.setEnabled(true);

        redoEdit = new JMenuItem("Redo");
        redoEdit.setMnemonic(KeyEvent.VK_R);
        redoEdit.addActionListener(this);
        redoEdit.setPreferredSize(new Dimension(100, 20));
        redoEdit.setEnabled(true);

        selectAll = new JMenuItem("Select All");
        selectAll.setMnemonic(KeyEvent.VK_S);
        selectAll.addActionListener(this);
        selectAll.setPreferredSize(new Dimension(100, 20));
        selectAll.setEnabled(true);

        copy = new JMenuItem("Copy");
        copy.setMnemonic(KeyEvent.VK_C);
        copy.addActionListener(this);
        copy.setPreferredSize(new Dimension(100, 20));
        copy.setEnabled(true);

        paste = new JMenuItem("Paste");
        paste.setMnemonic(KeyEvent.VK_P);
        paste.addActionListener(this);
        paste.setPreferredSize(new Dimension(100, 20));
        paste.setEnabled(true);

        cut = new JMenuItem("Cut");
        cut.setMnemonic(KeyEvent.VK_T);
        cut.addActionListener(this);
        cut.setPreferredSize(new Dimension(100, 20));
        cut.setEnabled(true);

        // Add items to menu
        editMenu.add(undoEdit);
        editMenu.add(redoEdit);
        editMenu.add(selectAll);
        editMenu.add(copy);
        editMenu.add(paste);
        editMenu.add(cut);
    }
    private void formatMenu() {
        formatMenu = new JMenu("Format");
        formatMenu.setMnemonic(KeyEvent.VK_O);
        formatMenu.setPreferredSize(new Dimension(60, 20));

        // Add file menu items
        fontColor= new JMenu("Font Color");
        fontColor.setMnemonic(KeyEvent.VK_C);
        fontColor.addActionListener(this);
        fontColor.setPreferredSize(new Dimension(100, 20));
        fontColor.setEnabled(true);

        fontSize= new JMenu("Font Style");
        fontSize.setMnemonic(KeyEvent.VK_S);
        fontSize.addActionListener(this);
        fontSize.setPreferredSize(new Dimension(100, 20));
        fontSize.setEnabled(true);

        // Add submenu items
        subColorRed= new JMenuItem("Red");
        subColorRed.setMnemonic(KeyEvent.VK_R);
        subColorRed.addActionListener(this);
        subColorRed.setPreferredSize(new Dimension(100, 20));
        subColorRed.setEnabled(true);

        subColorBlue= new JMenuItem("Blue");
        subColorBlue.setMnemonic(KeyEvent.VK_B);
        subColorBlue.addActionListener(this);
        subColorBlue.setPreferredSize(new Dimension(100, 20));
        subColorBlue.setEnabled(true);

        subColorGreen= new JMenuItem("Green");
        subColorGreen.setMnemonic(KeyEvent.VK_G);
        subColorGreen.addActionListener(this);
        subColorGreen.setPreferredSize(new Dimension(100, 20));
        subColorGreen.setEnabled(true);

        subColorBlack= new JMenuItem("Black");
        subColorBlack.setMnemonic(KeyEvent.VK_K);
        subColorBlack.addActionListener(this);
        subColorBlack.setPreferredSize(new Dimension(100, 20));
        subColorBlack.setEnabled(true);

        subTimes= new JMenuItem("Times New Roman");
        subTimes.setMnemonic(KeyEvent.VK_T);
        subTimes.addActionListener(this);
        subTimes.setPreferredSize(new Dimension(125, 20));
        subTimes.setEnabled(true);

        subArial= new JMenuItem("Arial");
        subArial.setMnemonic(KeyEvent.VK_A);
        subArial.addActionListener(this);
        subArial.setPreferredSize(new Dimension(100, 20));
        subArial.setEnabled(true);

        subCourier= new JMenuItem("Courier");
        subCourier.setMnemonic(KeyEvent.VK_C);
        subCourier.addActionListener(this);
        subCourier.setPreferredSize(new Dimension(100, 20));
        subCourier.setEnabled(true);

        subVerdana= new JMenuItem("Verdana");
        subVerdana.setMnemonic(KeyEvent.VK_V);
        subVerdana.addActionListener(this);
        subVerdana.setPreferredSize(new Dimension(100, 20));
        subVerdana.setEnabled(true);

        // Add items to menu
        formatMenu.add(fontColor);
        fontColor.add(subColorRed);
        fontColor.add(subColorBlue);
        fontColor.add(subColorGreen);
        fontColor.add(subColorBlack);
        formatMenu.add(fontSize);
        fontSize.add(subTimes);
        fontSize.add(subArial);
        fontSize.add(subCourier);
        fontSize.add(subVerdana);

    }
    private void helpMenu() {
        helpMenu = new JMenu("Help");
        helpMenu.setMnemonic(KeyEvent.VK_H);
        helpMenu.setPreferredSize(new Dimension(40, 20));

        // Add file menu items
        about = new JMenuItem("About");
        about.setMnemonic(KeyEvent.VK_A);
        about.addActionListener(this);
        about.setPreferredSize(new Dimension(100, 20));
        about.setEnabled(true);

        // Add items to menu
        helpMenu.add(about);
    }
    // Method for saving files - Removes duplication of code
    private void saveFile(File filename) {
        try {
            BufferedWriter writer = new BufferedWriter(new FileWriter(filename));
            writer.write(textArea.getText());
            writer.close();
            saved = true;
            window.setTitle("Text Editor - " + filename.getName());
        } catch (IOException err) {
            err.printStackTrace();
        }
    }

    // Method for quick saving files
    private void quickSave(File filename) {
        try {
            BufferedWriter writer = new BufferedWriter(new FileWriter(filename));
            writer.write(textArea.getText());
            writer.close();
        } catch (IOException err) {
            err.printStackTrace();
        }
    }

    // Method for opening files
    private void openingFiles(File filename) {
        try {
            openedFile = filename;
            FileReader reader = new FileReader(filename);
            textArea.read(reader, null);
            opened = true;
            window.setTitle("Text Editor - " + filename.getName());
        } catch (IOException err) {
            err.printStackTrace();
        }
    }

    @Override
    public void actionPerformed(ActionEvent event) {
        if(event.getSource() == newFile) {
            new DoesThisWork();
        } else if(event.getSource() == openFile) {
            JFileChooser open = new JFileChooser();
            open.showOpenDialog(null);
            File file = open.getSelectedFile();
            openingFiles(file);
        } else if(event.getSource() == saveFile) {
            JFileChooser save = new JFileChooser();
            File filename = save.getSelectedFile();
            if(opened == false && saved == false) {
                save.showSaveDialog(null);
                int confirmationResult;
                if(filename.exists()) {
                    confirmationResult = JOptionPane.showConfirmDialog(saveFile, "Replace existing file?");
                    if(confirmationResult == JOptionPane.YES_OPTION) {
                        saveFile(filename);
                    }
                } else {
                    saveFile(filename);
                }
            } else {
                quickSave(openedFile);
            }
        } else if(event.getSource() == saveAsFile) {
            JFileChooser saveAs = new JFileChooser();
            saveAs.showSaveDialog(null);
            File filename = saveAs.getSelectedFile();
            int confirmationResult;
            if(filename.exists()) {
                confirmationResult = JOptionPane.showConfirmDialog(saveAsFile, "Replace existing file?");
                if(confirmationResult == JOptionPane.YES_OPTION) {
                    saveFile(filename);
                }
            } else {
                saveFile(filename);
            }
        } else if(event.getSource() == pageSetup) {
            job = PrinterJob.getPrinterJob();
            format = job.pageDialog(job.defaultPage());
        } else if(event.getSource() == printFile) {
            job = PrinterJob.getPrinterJob();
            if(job.printDialog()) {
                try {
                    job.print();
                } catch (PrinterException err) {
                    err.printStackTrace();
                }
            }
        } else if(event.getSource() == exit) {
            System.exit(0);
        } else if(event.getSource() == undoEdit) {
            try {
                undo.undo();
            } catch(CannotUndoException cu) {
                cu.printStackTrace();
            }
        } else if(event.getSource() == redoEdit) {
            try {
                undo.redo();
            } catch(CannotUndoException cur) {
                cur.printStackTrace();
            }
        } else if(event.getSource() == selectAll) {
            textArea.selectAll();
        }  else if(event.getSource() == copy) {
            textArea.copy();
        } else if(event.getSource() == paste) {
            textArea.paste();
        } else if(event.getSource() == cut) {
            textArea.cut();
        } else if(event.getSource() == about){
            //createAboutFrame();
            JLabel About = new JLabel();
            About.setText("<html>"
                    + "<p>This is a custom Text Editor</p>"
                    + "<p>Built By Todd Eaton, October 2015</p>"
                    + "<p>Brandeis University</p>"
                    + "<p>Master of Software Engineering Candidate</p>");
            JOptionPane.showMessageDialog(null, About, "About Text Editor", JOptionPane.INFORMATION_MESSAGE);
        } else if(event.getSource() == subColorRed){
            textArea.setForeground(Color.RED);
        } else if(event.getSource() == subColorBlue) {
            textArea.setForeground(Color.BLUE);
        } else if(event.getSource() == subColorGreen) {
            textArea.setForeground(Color.GREEN);
        } else if(event.getSource() == subColorBlack) {
            textArea.setForeground(Color.BLACK);
        } else if(event.getSource() == subTimes){
            textFont = new Font("Times New Roman", 0, 14);
            textArea.setFont(textFont);
        } else if(event.getSource() == subArial){
            textFont = new Font("Arial", 0, 14);
            textArea.setFont(textFont);
        } else if(event.getSource() == subCourier){
            textFont = new Font("Courier", 0, 14);
            textArea.setFont(textFont);
        } else if(event.getSource() == subVerdana){
            textFont = new Font("Verdana", 0, 14);
            textArea.setFont(textFont);
        }


    }

    //============================================
    // GETTERS AND SETTERS
    //============================================

    public JTextArea getTextArea() {
        return textArea;
    }

    public void setTextArea(JTextArea text) {
        textArea = text;
    }
}

Answer 1

以下评论

//editorWindow.add(toolBar, BorderLayout.NORTH);

应替换为

editorWindow.add(createToolBar(), BorderLayout.NORTH);

实际创建工具栏并将其添加到用户界面。

Answer 2

您将JToolBar添加到JFrame创建的DoesThisWork实例中，但屏幕上实际上并未显示。

首先删除extends JFrame并依赖JFrame分配给editorWindow

的实例

然后在您的createEditorWindow方法中添加

 editorWindow.add(createToolBar(), BorderLayout.WEST);

（您需要修复通过删除extends JFrame生成的其他几个编译器错误，但它们应该非常明显）

Answer 3

//editorWindow.add(toolBar, BorderLayout.NORTH);

您不会将工具栏添加到框架中。

您是否意识到代码中有两个JFrame？您的类扩展了JFrame，然后在您的代码中也创建了另一个JFrame。有时您的代码只使用add(...)方法向组中添加组件。然后，有时您的代码会使用editorWindow.add(...)向框架中添加组件。

您的代码令人困惑，因为您有两个框架。不要扩展JFrame。

从How to Make Menus上的Swing教程中的MenuLookDemo代码开始。它将向您展示如何更好地构建代码，以便您不会有两个框架。＆＃34;创建＆＃34;方法实际上应该返回组件，以便将它们添加到框架中。

Jtoolbar没有显示

3 个答案: