Question

我目前有一个程序，可以在不同行的'System.out.println（）'语句中向屏幕打印文本行。我是Java，Eclipse和WindowBuilder的新手。

我现在正在为此程序添加GUI。我能够使用按钮创建GUI，这些按钮正常工作。我的问题是我想将打印到eclipse控制台（或命令行）的所有内容打印到我GUI中的文本框而不是实时。我怎么能这么容易地做到这一点？

package Onur;


import java.awt.BorderLayout;

public class BehaSendDFGUI extends JFrame {

    private BehaviourSendWithDF1 myAgent; // Reference to the agent class
    private JPanel contentPane;
    private JDesktopPane desktopPane;
    private JButton btnMessage;
    private JButton btnMessage_1;
    private JButton btnMessage_2;
    private JButton btnMessage_3;
    private JTextArea textArea = new JTextArea();

    public void setAgent(BehaviourSendWithDF1 a) {
        myAgent = a; // provide the value of the reference of BehaviourSendWithDF1 class here

    }

    private void updateTextArea(final String text) {
          SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                textArea.append(text);
            }
          });
        }

        private void redirectSystemStreams() {
          OutputStream out = new OutputStream() {
            @Override
            public void write(int b) throws IOException {
              updateTextArea(String.valueOf((char) b));
            }

            @Override
            public void write(byte[] b, int off, int len) throws IOException {
              updateTextArea(new String(b, off, len));
            }

            @Override
            public void write(byte[] b) throws IOException {
              write(b, 0, b.length);
            }
          };

          System.setOut(new PrintStream(out, true));
          System.setErr(new PrintStream(out, true));
        }

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        try {
            UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        } catch (Throwable e) {
            e.printStackTrace();
        }
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    BehaSendDFGUI frame = new BehaSendDFGUI();
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the frame.
     */
    public BehaSendDFGUI() {


        setTitle("Behaviour Sender");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 523, 398);

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

        JMenu mnFile = new JMenu("File");
        menuBar.add(mnFile);

        JMenuItem mntmExit = new JMenuItem("Exit");
        mnFile.add(mntmExit);

        JMenu mnAbout = new JMenu("About");
        menuBar.add(mnAbout);

        JMenuItem mntmAboutThisGui = new JMenuItem("About This GUI");
        mnAbout.add(mntmAboutThisGui);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        contentPane.setLayout(new BorderLayout(0, 0));
        setContentPane(contentPane);

        JToolBar toolBar = new JToolBar();
        toolBar.setFloatable(false);
        contentPane.add(toolBar, BorderLayout.CENTER);

        desktopPane = new JDesktopPane();
        toolBar.add(desktopPane);

        btnMessage = new JButton("Send Message 1");
        btnMessage.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                BehaviourSendWithDF1.STEP = "1";
                System.out.println("Button Pressed => STEP = " + BehaviourSendWithDF1.STEP );
                myAgent.behaSend();             
            }

        });
        btnMessage.setBounds(10, 11, 111, 23);
        desktopPane.add(btnMessage);

        btnMessage_1 = new JButton("Send Message 2");
        btnMessage_1.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                BehaviourSendWithDF1.STEP = "2";
                System.out.println("Button Pressed => STEP = " + BehaviourSendWithDF1.STEP );
                myAgent.behaSend(); 
            }
        });
        btnMessage_1.setBounds(131, 11, 111, 23);
        desktopPane.add(btnMessage_1);

        btnMessage_2 = new JButton("Send Message 3");
        btnMessage_2.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                BehaviourSendWithDF1.STEP = "3";
                System.out.println("Button Pressed => STEP = " + BehaviourSendWithDF1.STEP );
                myAgent.behaSend(); 
            }
        });
        btnMessage_2.setBounds(252, 11, 111, 23);
        desktopPane.add(btnMessage_2);

        btnMessage_3 = new JButton("Send Message 4");
        btnMessage_3.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                BehaviourSendWithDF1.STEP = "4";
                System.out.println("Button Pressed => STEP = " + BehaviourSendWithDF1.STEP );
                myAgent.behaSend(); 
            }
        });
        btnMessage_3.setBounds(373, 11, 111, 23);
        desktopPane.add(btnMessage_3);

        JButton btnExitGui = new JButton("Exit GUI");
        btnExitGui.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                dispose();
            }
        });
        btnExitGui.setBounds(189, 293, 130, 23);
        desktopPane.add(btnExitGui);

        JTextPane txtpnConsoleOutput = new JTextPane();
        txtpnConsoleOutput.setText("Console Output:");
        txtpnConsoleOutput.setBounds(10, 45, 101, 20);
        desktopPane.add(txtpnConsoleOutput);

        JScrollPane scrollPane = new JScrollPane();
        scrollPane.setBounds(10, 76, 475, 206);
        desktopPane.add(scrollPane);
        scrollPane.setViewportView(textArea);

        redirectSystemStreams();

    }
}

我在NetBeans上看到过这个解决方案，但无法将其应用于WindowBuilder：

http://unserializableone.blogspot.com/2009/01/redirecting-systemout-and-systemerr-to.html

先谢谢。

编辑：在问题中编辑代码的工作版本。感谢您的帮助。

Answer 1

您的问题包括

您正在尝试使用不存在的变量textPane和
您的程序没有可以显示文本的文本组件。我建议你至少添加一个JTextArea，这样你就可以将输出重定向到它。如果你愿意，可以把它称为textPane，但无论你怎么称呼它，你至少需要可以显示多行文字。
同样，您提供的链接中描述的一般技术是正确的 - 您需要将System.out和System.err重定向到您创建的OutputStream，
但是你必须注意只在Swing事件线程上更新Swing组件，因此使用SwingUtilities.invokeLater(new Runnable() {...}) ...
正确使用文章的建议将工作。所以坚持下去。

再次阅读Swing教程并将Windows构建器代码生成器放在一边。代码生成器可用于节省您的时间，但如果您在充分了解Swing库之前使用它们，那么在您需要的任何内容以及最基本的GUI和行为之外，您可能会遇到大问题。

修改
您似乎试图在JTextField上调用append(...)，并且此类不允许该消息。我建议

您大大简化了类，因此它只有最基本的GUI来演示System.out和err的重定向，并且

再次使用JTextArea，而不是JTextField。

编辑2
你问：

我无法解决'textArea.append（text）;'范围错误：无法解析textArea。

请注意声明 textArea变量的位置。由于它不是在类中声明，而是在方法或构造函数中声明，因此在类的其他地方不可见。解决方案是在课堂上声明它，而不是在别处。

编辑3
例如，

import java.awt.event.ActionEvent; import java.io.IOException; import java.io.OutputStream; import java.io.PrintStream; import javax.swing.*; @SuppressWarnings("serial") public class RedirectOut extends JPanel { private static final int BUTTON_COUNT = 4; private JTextArea textArea = new JTextArea(20, 20); private SomeAgent myAgent; public RedirectOut() { redirectSystemStreams(); setLayout(new BoxLayout(this, BoxLayout.PAGE_AXIS)); for (int i = 0; i < BUTTON_COUNT; i++) { final int count = i + 1; JButton button = new JButton(new AbstractAction("Send Message " + count){ @Override public void actionPerformed(ActionEvent e) { myAgent.setStep(String.valueOf(count)); System.out.println("Button Pressed => STEP = " + myAgent.getStep()); myAgent.behaSend(); } }); JPanel btnPanel = new JPanel(); btnPanel.add(button); add(btnPanel); } add(new JScrollPane(textArea, JScrollPane.VERTICAL_SCROLLBAR_ALWAYS, JScrollPane.HORIZONTAL_SCROLLBAR_NEVER)); } public void setAgent(SomeAgent agent) { this.myAgent = agent; } public void updateTextArea(final String text) { SwingUtilities.invokeLater(new Runnable() { public void run() { textArea.append(text); } }); } private void redirectSystemStreams() { OutputStream out = new OutputStream() { @Override public void write(int b) throws IOException { updateTextArea(String.valueOf((char) b)); } @Override public void write(byte[] b, int off, int len) throws IOException { updateTextArea(new String(b, off, len)); } @Override public void write(byte[] b) throws IOException { write(b, 0, b.length); } }; System.setOut(new PrintStream(out, true)); System.setErr(new PrintStream(out, true)); } private static void createAndShowGui() { RedirectOut redirectOut = new RedirectOut(); redirectOut.setAgent(new SomeAgent()); JFrame frame = new JFrame("RedirectOut"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.getContentPane().add(redirectOut); frame.pack(); frame.setLocationByPlatform(true); frame.setVisible(true); } public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { public void run() { createAndShowGui(); } }); } }

控制台输出到WindowBuilder GUI

1 个答案: