java - 带 GUI 的 BlueJ 时钟显示

Question

目前显示工作正常。我将运行分钟数编码为模拟时钟显示的秒数。它工作正常，但当它是 12:59 时，它应该是 1 而不是 0。我无法弄清楚删除 00:00 应该是 12:59 之后的 01:00。

时钟.java

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;

public class Clock
{
    private JFrame frame;
    private JLabel label;
    private ClockDisplay clock;
    private boolean clockRunning = false;
    private TimerThread timerThread;

    /**
     * Constructor for objects of class Clock
     */
    public Clock()
    {
        makeFrame();
        clock = new ClockDisplay();
    }

    /**
     * 
     */
    private void start()
    {
        clockRunning = true;
        timerThread = new TimerThread();
        timerThread.start();
    }

    /**
     * 
     */
    private void stop()
    {
        clockRunning = false;
    }

    /**
     * 
     */
    private void step()
    {
        clock.timeTick();
        label.setText(clock.getTime());
    }

    /**
     * 'About' function: show the 'about' box.
     */
    private void showAbout()
    {
        JOptionPane.showMessageDialog (frame, 
                    "Clock Version 1.0\n" +
                    "A simple interface for the 'Objects First' clock display project",
                    "About Clock", 
                    JOptionPane.INFORMATION_MESSAGE);
    }

    /**
     * Quit function: quit the application.
     */
    private void quit()
    {
        System.exit(0);
    }


    /**
     * Create the Swing frame and its content.
     */
    private void makeFrame()
    {
        frame = new JFrame("Clock");
        JPanel contentPane = (JPanel)frame.getContentPane();
        contentPane.setBorder(new EmptyBorder(1, 60, 1, 60));

        makeMenuBar(frame);

        // Specify the layout manager with nice spacing
        contentPane.setLayout(new BorderLayout(12, 12));

        // Create the image pane in the center
        label = new JLabel("00:00", SwingConstants.CENTER);
        Font displayFont = label.getFont().deriveFont(96.0f);
        label.setFont(displayFont);
        //imagePanel.setBorder(new EtchedBorder());
        contentPane.add(label, BorderLayout.CENTER);

        // Create the toolbar with the buttons
        JPanel toolbar = new JPanel();
        toolbar.setLayout(new GridLayout(1, 0));

        JButton startButton = new JButton("Start");
        startButton.addActionListener(e -> start());
        toolbar.add(startButton);

        JButton stopButton = new JButton("Stop");
        stopButton.addActionListener(e -> stop());
        toolbar.add(stopButton);

        JButton stepButton = new JButton("Step");
        stepButton.addActionListener(e -> step());
        toolbar.add(stepButton);

        // Add toolbar into panel with flow layout for spacing
        JPanel flow = new JPanel();
        flow.add(toolbar);

        contentPane.add(flow, BorderLayout.SOUTH);

        // building is done - arrange the components      
        frame.pack();

        // place the frame at the center of the screen and show
        Dimension d = Toolkit.getDefaultToolkit().getScreenSize();
        frame.setLocation(d.width/2 - frame.getWidth()/2, d.height/2 - frame.getHeight()/2);
        frame.setVisible(true);
    }

    /**
     * Create the main frame's menu bar.
     * 
     * @param frame   The frame that the menu bar should be added to.
     */
    private void makeMenuBar(JFrame frame)
    {
        final int SHORTCUT_MASK =
            Toolkit.getDefaultToolkit().getMenuShortcutKeyMask();

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

        JMenu menu;
        JMenuItem item;

        // create the File menu
        menu = new JMenu("File");
        menubar.add(menu);

        item = new JMenuItem("About Clock...");
            item.addActionListener(e -> showAbout());
        menu.add(item);

        menu.addSeparator();

        item = new JMenuItem("Quit");
            item.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_Q, SHORTCUT_MASK));
            item.addActionListener(e -> quit());
        menu.add(item);
    }

    class TimerThread extends Thread
    {
        public void run()
        {
            while (clockRunning) {
                step();
                pause();
            }
        }

        private void pause()
        {
            try {
                Thread.sleep(300);   // pause for 300 milliseconds
            }
            catch (InterruptedException exc) {
            }
        }
    }
}

clock.java 应该被锁定，因为它工作正常。

numDisplay.java

/**
 * The NumberDisplay class represents a digital number display that can hold
 * values from zero to a given limit. The limit can be specified when 
 * creating the display. The values range from zero (inclusive) to limit-1. 
 * If used,
 * for example, for the seconds on a digital clock, the limit would be 60, 
 * resulting in display values from 0 to 59. When incremented, the display 
 * automatically rolls over to zero when reaching the limit.
 */
public class NumberDisplay
{
    private int limit = 13;
    private int value;

    /**
     * Constructor for objects of class NumberDisplay.
     * Set the limit at which the display rolls over.
     */
    public NumberDisplay(int rollOverLimit)
    {
        limit = rollOverLimit; 
        value = 1;
    }
    /*
     * 
     */

    /**
     * Return the current value.
     */
    public int getValue()
    {
        return value;
    }

    /**
     * Return the display value (that is, the current value as a two-digit
     * String. If the value is less than ten, it will be padded with a leading
     * zero).
     */
    public String getDisplayValue()
    {
        if(value < 10) {
            return "0" + value; // stay 0 appears in left 
        }
        else {
            return "" + value; // none to show in right of the display
        }
    }

    /**
     * Set the value of the display to the new specified value. If the new
     * value is less than zero or over the limit, do nothing.
     */
    public void setValue(int replacementValue)
    {
        if((replacementValue >= 2) & (replacementValue < limit)) {
            value = replacementValue;
        }
    }

    /**
     * Increment the display value by one, rolling over to zero if the
     * limit is reached.
     */
    public void increment()
    {
        value = (value + 1) % limit; // this is already the time by 1 
    }
}

我还留下了评论，以帮助了解他们正在运行的程序。

这是最后一个名为“Display”的项目，名为 ClockDisplay.java:

/**
 * The ClockDisplay class implements a digital clock display for a
 * European-style 24 hour clock. The clock shows hours and minutes. The 
 * range of the clock is 00:00 (midnight) to 23:59 (one minute before 
 * midnight).
 * 
 * The clock display receives "ticks" (via the timeTick method) every minute
 * and reacts by incrementing the display. This is done in the usual clock
 * fashion: the hour increments when the minutes roll over to zero.
 */
public class ClockDisplay
{
    private NumberDisplay hours;    // runs from 1 am/pm to 11:59 am/pm
    private NumberDisplay minutes;  // This will running like 
                                    //  seconds act as minutes.
    private String displayString;    // simulates the actual display

    /**
     * Constructor for ClockDisplay objects. This constructor 
     * creates a new clock set at 00:00.
     */
    public ClockDisplay()
    {
        hours = new NumberDisplay(13); // set great than 13; runs from 1am to 12 noon
        minutes = new NumberDisplay(60); // 60 minutes is one hour
        updateDisplay();
    }

    /**
     * Constructor for ClockDisplay objects. This constructor
     * creates a new clock set at the time specified by the 
     * parameters.
     */
    public ClockDisplay(int hour, int minute)
    {
        hours = new NumberDisplay(13);
        minutes = new NumberDisplay(60);
        setTime(hour, minute);
    }

    /**
     * This method should get called once every minute - it makes
     * the clock display go one minute forward.
     */
    public void timeTick()
    {
        minutes.increment();
        if(minutes.getValue() == 1) {  // on clock at after 12 am or pm.
            hours.increment(); // after 60 mins, next per hour.
        }
        updateDisplay(); // updating to return 
    }

    /**
     * Set the time of the display to the specified hour and
     * minute.
     */
    public void setTime(int hour, int minute)
    {
        hours.setValue(hour);       // hours will be set on display
        minutes.setValue(minute);   // minutes will be set on display
        updateDisplay();            // updating the value to display
    }

    /**
     * Return the current time of this display in the format HH:MM.
     */
    public String getTime()
    {
        return displayString; // appears as messagebox to display the clock
    }

    /**
     * Update the internal string that represents the display.
     */
    private void updateDisplay()
    {
        displayString = hours.getDisplayValue() + ":" + 
                        minutes.getDisplayValue(); //Updated the clock simulator 
    }
}

我仍然停留在 00:00。需要帮助吗？

Answer 1

您的代码中有很多地方可以更好地管理。

让我们从...开始

public void increment() {
    value = (value + 1) % limit; // this is already the time by 1 
}

我可以看到你想要做什么，但请记住 13 % 13 是 0，这是你问题的起点，虽然确实很聪明，但我会使用 setValue(value + 1) 并允许 setValue 执行验证。

这样做的原因是，您可以提供最小和最大允许值，然后 setValue 可以管理这些值。

然后，我将更改 increment 方法，使其在“滚动”值时返回 true，这样可以更轻松地确定值何时恢复到其值最低状态。

为了简洁起见，这些是基本的变化......

数字显示

public class NumberDisplay {

    private int minimum = 1;
    private int maximum = 13;
    private int value;

    /**
     * Constructor for objects of class NumberDisplay. Set the limit at
     * which the display rolls over.
     */
    public NumberDisplay(int maxumum, int minimum) {
        this.maximum = maxumum;
        this.minimum = minimum;
        value = 1;
    }

    //...

    /**
     * Set the value of the display to the new specified value. If the new
     * value is less than zero or over the limit, do nothing.
     */
    public boolean setValue(int replacementValue) {
        if (replacementValue >= maximum) {
            value = minimum;
            return true;
        } else {
            value = replacementValue;
            return false;
        }
    }

    /**
     * Increment the display value by one, rolling over to zero if the limit
     * is reached.
     */
    public boolean increment() {

//值 = (值 + 1) % 最大值；//这已经是时间 1 返回设置值(值+1)； } }

时钟显示

public class ClockDisplay {

        //...

        /**
         * This method should get called once every minute - it makes the clock
         * display go one minute forward.
         */
        public void timeTick() {
            if (minutes.increment()) {  // on clock at after 12 am or pm.
                hours.increment(); // after 60 mins, next per hour.
            }
            updateDisplay(); // updating to return 
        }

        //...

}

完整示例....

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.Toolkit;
import java.awt.event.KeyEvent;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.SwingConstants;
import javax.swing.SwingUtilities;
import javax.swing.border.EmptyBorder;

public class Clock {

    private JFrame frame;
    private JLabel label;
    private ClockDisplay clock;
    private boolean clockRunning = false;
    private TimerThread timerThread;

    public static void main(String[] args) {
        System.out.println((13 % 13));
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new Clock();
            }
        });
    }

    /**
     * Constructor for objects of class Clock
     */
    public Clock() {
        makeFrame();
        clock = new ClockDisplay(12, 0);
    }

    /**
     *
     */
    private void start() {
        clockRunning = true;
        timerThread = new TimerThread();
        timerThread.start();
    }

    /**
     *
     */
    private void stop() {
        clockRunning = false;
    }

    /**
     *
     */
    private void step() {
        clock.timeTick();
        label.setText(clock.getTime());
    }

    /**
     * 'About' function: show the 'about' box.
     */
    private void showAbout() {
        JOptionPane.showMessageDialog(frame,
                "Clock Version 1.0\n"
                + "A simple interface for the 'Objects First' clock display project",
                "About Clock",
                JOptionPane.INFORMATION_MESSAGE);
    }

    /**
     * Quit function: quit the application.
     */
    private void quit() {
        System.exit(0);
    }

    /**
     * Create the Swing frame and its content.
     */
    private void makeFrame() {
        frame = new JFrame("Clock");
        JPanel contentPane = (JPanel) frame.getContentPane();
        contentPane.setBorder(new EmptyBorder(1, 60, 1, 60));

        makeMenuBar(frame);

        // Specify the layout manager with nice spacing
        contentPane.setLayout(new BorderLayout(12, 12));

        // Create the image pane in the center
        label = new JLabel("12:00", SwingConstants.CENTER);
        Font displayFont = label.getFont().deriveFont(96.0f);
        label.setFont(displayFont);
        //imagePanel.setBorder(new EtchedBorder());
        contentPane.add(label, BorderLayout.CENTER);

        // Create the toolbar with the buttons
        JPanel toolbar = new JPanel();
        toolbar.setLayout(new GridLayout(1, 0));

        JButton startButton = new JButton("Start");
        startButton.addActionListener(e -> start());
        toolbar.add(startButton);

        JButton stopButton = new JButton("Stop");
        stopButton.addActionListener(e -> stop());
        toolbar.add(stopButton);

        JButton stepButton = new JButton("Step");
        stepButton.addActionListener(e -> step());
        toolbar.add(stepButton);

        // Add toolbar into panel with flow layout for spacing
        JPanel flow = new JPanel();
        flow.add(toolbar);

        contentPane.add(flow, BorderLayout.SOUTH);

        // building is done - arrange the components      
        frame.pack();

        // place the frame at the center of the screen and show
        Dimension d = Toolkit.getDefaultToolkit().getScreenSize();
        frame.setLocation(d.width / 2 - frame.getWidth() / 2, d.height / 2 - frame.getHeight() / 2);
        frame.setVisible(true);
    }

    /**
     * Create the main frame's menu bar.
     *
     * @param frame The frame that the menu bar should be added to.
     */
    private void makeMenuBar(JFrame frame) {
        final int SHORTCUT_MASK
                = Toolkit.getDefaultToolkit().getMenuShortcutKeyMask();

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

        JMenu menu;
        JMenuItem item;

        // create the File menu
        menu = new JMenu("File");
        menubar.add(menu);

        item = new JMenuItem("About Clock...");
        item.addActionListener(e -> showAbout());
        menu.add(item);

        menu.addSeparator();

        item = new JMenuItem("Quit");
        item.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_Q, SHORTCUT_MASK));
        item.addActionListener(e -> quit());
        menu.add(item);
    }

    class TimerThread extends Thread {

        public void run() {
            while (clockRunning) {
                step();
                pause();
            }
        }

        private void pause() {
            try {
                Thread.sleep(300);   // pause for 300 milliseconds
            } catch (InterruptedException exc) {
            }
        }
    }

    public class NumberDisplay {

        private int minimum = 1;
        private int maximum = 13;
        private int value;

        /**
         * Constructor for objects of class NumberDisplay. Set the limit at
         * which the display rolls over.
         */
        public NumberDisplay(int maxumum, int minimum) {
            this.maximum = maxumum;
            this.minimum = minimum;
            value = 1;
        }

        /*
     * 
         */
        /**
         * Return the current value.
         */
        public int getValue() {
            return value;
        }

        /**
         * Return the display value (that is, the current value as a two-digit
         * String. If the value is less than ten, it will be padded with a
         * leading zero).
         */
        public String getDisplayValue() {
            if (value < 10) {
                return "0" + value; // stay 0 appears in left 
            } else {
                return "" + value; // none to show in right of the display
            }
        }

        /**
         * Set the value of the display to the new specified value. If the new
         * value is less than zero or over the limit, do nothing.
         */
        public boolean setValue(int replacementValue) {
            if (replacementValue >= maximum) {
                value = minimum;
                return true;
            } else {
                value = replacementValue;
                return false;
            }
        }

        /**
         * Increment the display value by one, rolling over to zero if the limit
         * is reached.
         */
        public boolean increment() {
//            value = (value + 1) % maximum; // this is already the time by 1 
            return setValue(value + 1);
        }
    }

    public class ClockDisplay {

        private NumberDisplay hours;    // runs from 1 am/pm to 11:59 am/pm
        private NumberDisplay minutes;  // This will running like 
        //  seconds act as minutes.
        private String displayString;    // simulates the actual display

        /**
         * Constructor for ClockDisplay objects. This constructor creates a new
         * clock set at 00:00.
         */
        public ClockDisplay() {
            hours = new NumberDisplay(13, 1); // set great than 13; runs from 1am to 12 noon
            minutes = new NumberDisplay(60, 0); // 60 minutes is one hour
            updateDisplay();
        }

        /**
         * Constructor for ClockDisplay objects. This constructor creates a new
         * clock set at the time specified by the parameters.
         */
        public ClockDisplay(int hour, int minute) {
            this();
            setTime(hour, minute);
        }

        /**
         * This method should get called once every minute - it makes the clock
         * display go one minute forward.
         */
        public void timeTick() {
            if (minutes.increment()) {  // on clock at after 12 am or pm.
                hours.increment(); // after 60 mins, next per hour.
            }
            updateDisplay(); // updating to return 
        }

        /**
         * Set the time of the display to the specified hour and minute.
         */
        public void setTime(int hour, int minute) {
            System.out.println("setTime " + hour + ":" + minute);
            hours.setValue(hour);       // hours will be set on display
            minutes.setValue(minute);   // minutes will be set on display
            updateDisplay();            // updating the value to display
        }

        /**
         * Return the current time of this display in the format HH:MM.
         */
        public String getTime() {
            return displayString; // appears as messagebox to display the clock
        }

        /**
         * Update the internal string that represents the display.
         */
        private void updateDisplay() {
            displayString = hours.getDisplayValue() + ":"
                    + minutes.getDisplayValue(); //Updated the clock simulator 
        }
    }
}

旁注

您还需要更好地了解 Swing 中的并发性。 Swing 不是线程安全的，您永远不应该从事件调度线程的上下文之外修改 UI 或 UI 所依赖的内容，请参阅 Concurrency in Swing更多细节。一个Swing Timer在这种情况下，将是比 Thread 更好的选择