java - 使用 Jframe/文本字段打印数字

Question

如何使用 Eclipse 中的 WindowBuilder 将 for 循环中的数字打印到文本字段中，我已经制作了 for 循环，以便在单击开始时开始计数器(最多计数 60)。我只是想知道当我单击“开始”时，如何使其显示在不同的文本字段中。如果这个解释不太清楚，换句话说，我正在制作一个秒表，当您单击开始时，它会在 Eclipse 控制台中打印最多 60 。我希望当我单击开始时这些数字显示在窗口的 JTextfield 中。任何帮助表示赞赏:)

这是代码页，我希望你们(或女孩)可以帮助我:)(这就是我试图做的。

package com.racecar484.user;

import java.awt.EventQueue;

import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.SwingConstants;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.Color;
import javax.swing.JLabel;
import javax.swing.JTable;

public class StopWatch extends ForLoopTesting {

    private JFrame frmStopWatchPro;
    private JTextField txtClickMeTo;
    private JButton Terminate;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    StopWatch window = new StopWatch();
                    window.frmStopWatchPro.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the application.
     */
    public StopWatch() {
        initialize();
    }

    /**
     * Initialize the contents of the frame.
     * @param i 
     */



    private void initialize(String i) {
        frmStopWatchPro = new JFrame();
        frmStopWatchPro.getContentPane().setBackground(new Color(255, 127, 80));
        frmStopWatchPro.setTitle("Stop Watch Pro");
        frmStopWatchPro.setBounds(100, 100, 450, 300);
        frmStopWatchPro.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frmStopWatchPro.getContentPane().setLayout(null);

        txtClickMeTo = new JTextField();
        for(int i1 = 0; i1 < 60; i1++){
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }
        }

        txtClickMeTo.setText(i);
        txtClickMeTo.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent arg0) {

            System.out.println("Oh my god this worked!");

            }
        });
        txtClickMeTo.setEditable(false);
        txtClickMeTo.setBounds(19, 24, 300, 58);
        frmStopWatchPro.getContentPane().add(txtClickMeTo);
        txtClickMeTo.setColumns(10);

        JButton btnNewButton = new JButton("Start");
        btnNewButton.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                System.out.println("Stop-Watch activated.");
                for(int i = 0; i < 60; i++){
                    System.out.println(i);
                    try {
                        Thread.sleep(1000);
                    } catch (InterruptedException e1) {
                        // TODO Auto-generated catch block
                        e1.printStackTrace();
                    }
                }
            }
        });
        btnNewButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
            }
        });
        btnNewButton.setBounds(53, 121, 108, 40);
        frmStopWatchPro.getContentPane().add(btnNewButton);

        JButton btnStop = new JButton("Stop");
        btnStop.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
            String Meow = "hey";
                System.out.println("Stop-Watch stopped.");
            }
        });
        btnStop.setBounds(211, 121, 108, 40);
        frmStopWatchPro.getContentPane().add(btnStop);

        Terminate = new JButton("Terminate");
        Terminate.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {

            frmStopWatchPro.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                System.out.println("Closing Application.");
            System.exit(0);
            }
        });
        Terminate.setBounds(329, 0, 105, 261);
        frmStopWatchPro.getContentPane().add(Terminate);

        JLabel lblonlyOneThat = new JLabel("(Only one that actually works without console ->)");
        lblonlyOneThat.setBounds(53, 211, 266, 39);
        frmStopWatchPro.getContentPane().add(lblonlyOneThat);

        JLabel lblStopWatchPro = new JLabel("Stop Watch Pro V.1- made by Andrew Lopez ");
        lblStopWatchPro.setBounds(53, 187, 257, 29);
        frmStopWatchPro.getContentPane().add(lblStopWatchPro);
    }
}

Answer 1

Swing 是单线程的，这意味着如果您执行任何阻塞事件调度线程的操作，例如运行循环、使用 Thread.sleep 或其他一些长时间运行的进程，则 UI 将不会已更新(并且不会处理任何新事件)。

Swing 也不是线程安全的，这意味着您永远不应该从 EDT 之外的任何线程更新 UI

首先查看 Concurrency in Swing了解更多详情。

那么问题来了，如何解决这个问题呢？您可以使用 Thread 和 SwingUtilities.invokeLater，但这有点困惑。您可以使用 SwingWorker，但这对于解决问题来说有点过于严厉。最好的解决方案是使用 Swing Timer，它会在 EDT 内定期调用已注册的回调 (ActionListener)，从而可以安全地从内部更新 UI .

看看How to use Swing Timers了解更多详细信息。

举个例子......

import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class StopWatch {

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

    public StopWatch() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        private JTextField field;
        private Timer timer;
        private int counter;

        public TestPane() {
            setLayout(new GridBagLayout());
            GridBagConstraints gbc = new GridBagConstraints();
            gbc.gridwidth = GridBagConstraints.REMAINDER;
            field = new JTextField(4);
            add(field, gbc);

            JButton btn = new JButton("Start");
            btn.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    if (timer.isRunning()) {
                        timer.stop();
                        btn.setText("Start");
                    } else {
                        counter = 0;
                        timer.start();
                        field.setText(Integer.toString(counter));
                        btn.setText("Stop");
                    }
                }
            });
            add(btn, gbc);

            timer = new Timer(1000, new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    counter++;
                    if (counter >= 60) {
                        timer.stop();
                        btn.setText("Start");
                    }
                    field.setText(Integer.toString(counter));
                }
            });

        }

    }

}

Cavet:这是一个简单的示例。 Swing Timer 仅保证它会在规定的延迟后调用 ActionListener，这使得它稍微不准确(以毫秒为单位)。更“合适”的解决方案是比较 Timer 启动时间和 ActionListener 收到通知的时间

您可能还想查看How to Use Buttons, Check Boxes, and Radio Buttons和 How to Write an Action Listeners用于使用按钮的更合适的机制