Java me Java ME日历未显示

我一直在这里学习本教程：。但我似乎无法正确显示应用程序。当我运行应用程序时，我希望看到教程中类似CalendarCanvas的屏幕，但我得到了以下结果：

这是我的代码，我使用的是标准的MIDP类

类创建日历：

import java.util.Date;
import java.util.Calendar;
import javax.microedition.lcdui.*;
import javax.microedition.midlet.MIDlet;


public class CreateCalendar
{
    /**
     * Array of strings which holds data for the month and day 
     * for the calendar application.
     */
    static final String[] month_labels = new String[]
    {
        "January", "Febuary", "March", "April", "May", "June", "July", "August", "Sepetember", "October", "November", "Decemeber"
    };
    static final String[] weekdays_labels = new String[]
    {
        "Mon", "Tue", "Wed", "Thur", "Fri", "Sat", "Sun"
    };

    public int startWeekday = 0;
    public int padding = 1;
    public int borderWidth = 4;
    public int borderColor = 0x009900;

    /**
     * Weekday Labels
     */
    public Font weekdayFont = Font.getDefaultFont();
    public int weekdayBackgroundColor = 0x009900;
    public int weekdayColor = 0xffffff;

    /**
     * Month/Year Labels
     */
    public Font headerFont = Font.getDefaultFont();
    public int headerBackgroundColor = 0x009900;
    public int headerColor = 0xffffff;

    /**
     * Cells Labels
     */
    public Font font = Font.getDefaultFont();
    public int foreColor = 0xffffff;
    public int backgroundColor = 0x009900;
    public int selectedBackgroundColor = 0xCCFF00;
    public int selectedForegroundColor = 0xffffff;

    /**
     * Size properties 
     */
    int width = 0;
    int height = 0;
    int headerHeight = 0;
    int weekHeight = 0;
    int cellWidth = 0;
    int cellHeight = 0;

    /**
     * Internal time properties
     */
    long currentTimeStamp = 0;
    Calendar calendar = null;
    int weeks = 0;

    public CreateCalendar(Date date)
    {
    calendar = Calendar.getInstance();
    setDate(date);
    initialize();
    }

    public Date getSelectedDate()
    {
        return calendar.getTime();
    }

    public void setDate(Date d)
    {
        currentTimeStamp = d.getTime();
        calendar.setTime(d);
        this.weeks = (int)Math.ceil(((double)getStartWeekday() + getMonthDays()) / 7);
    }

    public void setDate(long timestamp)
    {
        setDate(new Date(timestamp));
    }

    public void initialize()
    {
        this.cellWidth = font.stringWidth("MM") + 2 * padding;
        this.cellHeight = font.getHeight() + 2 * padding;
        this.headerHeight = headerFont.getHeight() + 2 * padding;
        this.weekHeight = weekdayFont.getHeight() + 2 * padding;
        this.width = 7 * (cellWidth + borderWidth) + borderWidth;
        initHeight();
    }

    void initHeight()
    {
        this.height = headerHeight + weekHeight + this.weeks * (cellHeight + borderWidth) + borderWidth;
    }

    int getMonthDays()
    {
        int month = calendar.get(Calendar.MONTH);
        switch (month)
        {
            case 3:
            case 5:
            case 8:
            case 10:
                return 30;    
            case 1:
                int year = calendar.get(Calendar.YEAR);
                return (year % 4 == 0 && year % 100 != 0) || (year % 400 == 0) ? 29 : 28;
            default:
                return 31;
        }
    }

    int getStartWeekday()
    {
        Calendar c = Calendar.getInstance();
        c.set(Calendar.MONTH, calendar.get(Calendar.MONTH));
        c.set(Calendar.YEAR, calendar.get(Calendar.YEAR));
        c.set(Calendar.DAY_OF_MONTH, 1);
        return (c.get(Calendar.DAY_OF_WEEK) + 5) % 7;
    }

    public void KeyPressed(int key)
    {
        switch(key)
        {
            case Canvas.UP:
                go(-7);
                break;
            case Canvas.DOWN:
                go(7);
                break;
            case Canvas.RIGHT:
                go(1);
                break;
            case Canvas.LEFT:
                go(-1);
                break; 
        }
    }

    void go(int delta)
    {
        int prevMonth = calendar.get(Calendar.MONTH);
        setDate(currentTimeStamp + 864000000 * delta);
        if(calendar.get(Calendar.MONTH) != prevMonth)
        {
            initHeight();
        }
    }

    public void paint(Graphics g)
    {
        g.setColor(backgroundColor);
        g.fillRect(0, 0, width, height);
        g.setFont(headerFont);
        g.setColor(headerColor);
        g.drawString(month_labels[calendar.get(Calendar.MONTH)] + " " + calendar.get(Calendar.YEAR), width / 2, padding, Graphics.TOP | Graphics.HCENTER);
        g.translate(0, headerHeight);
        g.setColor(weekdayBackgroundColor);
        g.fillRect(0, 0, width, weekHeight);
        g.setColor(weekdayColor);
        g.setFont(weekdayFont);

        for(int i = 0; i < 7; i++)
        {
            g.drawString(weekdays_labels[(i + startWeekday) % 7], borderWidth + i * (cellWidth + borderWidth) + cellWidth / 2, padding, Graphics.TOP | Graphics.HCENTER);
        }

        g.translate(0, weekHeight);
        g.setColor(borderColor);

        for(int i = 0; i <= weeks; i++)
        {
            g.fillRect(0, i * (cellHeight + borderWidth), width, borderWidth);
        }
        for(int i = 0; i <=7; i++)
        {
            g.fillRect(i * (cellWidth + borderWidth), 0, borderWidth, height - headerHeight - weekHeight);
        }

        int days = getMonthDays();
        int dayIndex = (getStartWeekday() - this.startWeekday + 7) % 7;
        g.setColor(foreColor);
        int currentDay = calendar.get(Calendar.DAY_OF_MONTH);

        for(int i = 0; i < days; i++)
        {
            int weekday = (dayIndex + i) % 7;
            int row = (dayIndex + i) / 7;
            int x = borderWidth + weekday * (cellWidth + borderWidth) + cellWidth / 2;
            int y = borderWidth + row * (cellHeight + cellWidth) + padding;

            if(i + 1 == currentDay)
            {
                g.setColor(selectedBackgroundColor);
                g.fillRect(borderWidth + weekday * (cellWidth + borderWidth), borderWidth + row * (cellHeight + borderWidth), cellWidth, cellHeight);
                g.setColor(selectedForegroundColor);
            }

            g.drawString("" + (i + 1), x, y, Graphics.TOP | Graphics.HCENTER);

            if(i + 1 == currentDay)
            {
                g.setColor(foreColor);
            }
        }
        g.translate(0, - headerHeight - weekHeight);
    }

    private Date getTime() {
        throw new UnsupportedOperationException("Not yet implemented"); //TODO get current Time
    }

---

类CreateCalendar中的代码看起来很有问题

在本文中，您提到了对教程中的代码所做的一些小的变量名差异，但从代码片段中显示的情况来看，情况并非如此

为了找到重用教程代码的方法，最简单的方法如下所示

从教程文件CalendarWidget.java和CalendarCanvas.java复制源代码
按原样复制，仅在必要时调整程序包语句

修改

CalFrontEnd

about如下

• 如果需要，为CalendarCanvas添加导入语句
• 用CalendarCanvas的最简单调用替换startApp中的当前代码，如下所示： public void startApp() { Display.getDisplay(this).setCurrent( new CalendarCanvas(this)); } 公开作废startApp（）{ Display.getDisplay（this）.setCurrent( 新日历画布（本））； }

测试代码，调整并修复它，直到你的MIDlet显示出你对CalendarCanvas的期望

完成上述操作后，继续修改代码以进一步满足您的需要。
别忘了测试您所做的更改，以确保事情确实如您所期望的那样工作

---

最有可能出错的第一件事是方法的名称

按键

。Java是区分大小写的，您所参考的教程中，它类似于按

键

，从小写的

k

开始，这对于匹配Canvas API很重要。此外，您的个人无法判断新intCalendar（this）中发生了什么，这使得您无法判断出发生了什么问题 public void startApp() { Display.getDisplay(this).setCurrent( new CalendarCanvas(this)); }