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在CalendarCanvas课堂上，我们的想法是在日历中的任何一天按下，然后将显示一个表格，其中包含用户选择的当天的实际日期（不仅仅是今天的日期，因为它现在正在做）并且表格下方将是相关的图像到表格（例如 6 月 21 日 ( image.jpg)）。

我有两个问题。

第一，该程序只喜欢一张图片，即Men.img. 它将以所有三种形式显示该图像。其他两个图像根本不会显示。

我不明白，因为我一开始是从一种形式开始的，images.jpg图像和图像有效。我所做的只是创建 2 个新表单并切换图像的顺序。

我什至减小了尺寸（宽度/高度和 KB）以匹配，Men.jpg但它仍然没有显示。ImageItem 构造函数中的字符串甚至不显示。

最后，如何创建该calendar.getSelectedDate().toString()方法的新实例以显示新用户选择的日期，以便在用户选择不同的日期时将其放在图像上方？

在该keyPressed方法中，注释掉的 Alert 新实例将为我执行此操作，但我不想要警报，我希望它是与用户选择的日期有关的表单的标题。

下面是我的代码：

类 CalendarMidlet：

import java.io.IOException;
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;

/**
 * @author addylesson
 */
public class CalendarMidlet extends MIDlet {
    private Display mydisplay;
    private Command f;
    private Displayable d;

    public CalendarMidlet(){}

    public void startApp() {
        d = new CalendarCanvas(this);

        f = new Command("Exit", Command.EXIT, 0);
        d.addCommand(f);
        d.setCommandListener(new CommandListener()
        {
            public void commandAction(Command c, Displayable s)
            {

                if(c == f)

            notifyDestroyed();
            }
        } );

        mydisplay = Display.getDisplay(this);
        mydisplay.setCurrent(d);

    }




    public void startOver() {

        final Displayable d = new CalendarCanvas(this);

        d.addCommand(f);

        d.setCommandListener(new CommandListener()
        {
            public void commandAction(Command c, Displayable s)
            {

                if(c == f)

            notifyDestroyed();
            }
        } );
        mydisplay.setCurrent(d);
    }

    public void pauseApp() {
    }

    public void destroyApp(boolean unconditional) {
    }

}

类日历画布：

import java.io.IOException;
import java.util.Date;

import javax.microedition.lcdui.*;
import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;

public class CalendarCanvas extends Canvas
{
    CalendarWidget calendar = null;
    CalendarMidlet midlet = null;
        private Alert alert;
        private List mList;
        private Command f,e,n;
        private Display mydisplay;
        private Form form;
        private Form form2;
        private Form form3;
        private ImageItem imageItem;
        private ImageItem imageItem2;
        private ImageItem imageItem3;



    public CalendarCanvas(final CalendarMidlet m)
    {
        String day = calendar.getSelectedDate().toString();

                this.midlet = m;

        calendar = new CalendarWidget(new Date());

        calendar.headerFont = Font.getFont(Font.FACE_PROPORTIONAL, Font.STYLE_BOLD, Font.SIZE_LARGE);
        calendar.weekdayFont = Font.getFont(Font.FACE_PROPORTIONAL, Font.STYLE_BOLD, Font.SIZE_MEDIUM);
        calendar.weekdayBgColor = 0xccccff;
        calendar.weekdayColor = 0x0000ff;
        calendar.headerColor = 0xffffff;

                form = new Form(day);
                form2 = new Form("New Page");
                form3 = new Form("New Page");

                try 
                {
                    imageItem = new ImageItem(
                        "Men In Black 3: ",
                        Image.createImage("Men.jpg"),
                        ImageItem.LAYOUT_DEFAULT,
                        "DuKe");
                    form.append(imageItem);
                } catch(Exception s) {}

                try 
                {
                    imageItem2 = new ImageItem(
                        "Jordon vs Knicks: ",
                        Image.createImage("images.jpg"),
                        ImageItem.LAYOUT_DEFAULT,
                        "Not");
                    form2.append(imageItem2);
                } catch(Exception s) {}
                try 
                {
                    imageItem3 = new ImageItem(
                        "Horoscope: ",
                        Image.createImage("Men.jpg"),
                        ImageItem.LAYOUT_DEFAULT,
                        "DuKe");
                    form3.append(imageItem3);
                } catch(Exception s) {}

                alert = new Alert("Listen", "On this day "
                        +calendar.getSelectedDate().toString()+ "stuff happened", null, null);
                alert.setTimeout(Alert.FOREVER);


                n = new Command("Next", Command.SCREEN,0);
                f = new Command("Back", Command.BACK, 0);
                e = new Command("Exit", Command.EXIT, 1);
                form.addCommand(f);             
                form.addCommand(n);
                form2.addCommand(f);
                form2.addCommand(n);
                form3.addCommand(f);
                form3.addCommand(e);



                form.setCommandListener(new CommandListener()
                      {
                      public void commandAction(Command c, Displayable s)
                        {
                            if (c == f)

                            m.startOver();

                            if (c == e)
                                 m.notifyDestroyed();

                            if (c == n)
                                 Display.getDisplay(midlet).setCurrent(form2);
                        }
                      } );
                form2.setCommandListener(new CommandListener()
                      {
                      public void commandAction(Command c, Displayable s)
                        {
                            if (c == f)

                            m.startOver();

                            if (c == e)
                                 m.notifyDestroyed();

                            if (c == n)
                                 Display.getDisplay(midlet).setCurrent(form3);
                        }
                      } );
                form3.setCommandListener(new CommandListener()
                      {
                      public void commandAction(Command c, Displayable s)
                        {
                            if (c == f)

                            m.startOver();

                            if (c == e)
                                m.notifyDestroyed();
                        }
                      } );


        calendar.initialize();
    }


    protected void keyPressed(int key)
    {
        int keyCode = getGameAction(key);
        String day = calendar.getSelectedDate().toString();
        if(keyCode == FIRE)
        {
             /*Display.getDisplay(midlet).setCurrent(
                new Alert("Selected date", 
                                day, null, 
                                AlertType.CONFIRMATION)
            );*/
                       Display.getDisplay(midlet).setCurrent(form);
        }
        else
        {
            calendar.keyPressed(keyCode);

            repaint();
        }
    }

    protected void paint(Graphics g)
    {
        g.setColor(0xff0000);
        g.fillRect(0, 0, getWidth(), getHeight());

        calendar.paint(g);
    }

}

类日历小部件：

import java.util.Calendar;
import java.util.Date;

import javax.microedition.lcdui.*;

public class CalendarWidget
{
    static final String[] MONTH_LABELS = new String[]{
        "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"
    };
    static final String[] WEEKDAY_LABELS = new String[]{
        "M", "T", "W", "T", "F", "S", "S"
    };
    /* starting week day: 0 for monday, 6 for sunday */
    public int startWeekday = 0;

    /* elements padding */
    public int padding = 2;

    /* cells border properties */
    public int borderWidth = 4;
    public int borderColor = 0x000000;

    /* weekday labels properties */
    public Font weekdayFont = Font.getDefaultFont();
    public int weekdayBgColor = 0xcccccc;
    public int weekdayColor = 0xffffff;

    /* header (month-year label) properties */
    public Font headerFont = Font.getDefaultFont();
    public int headerBgColor = 0xff0000;
    public int headerColor = 0xff0000;

    /* cells properties */
    public Font font = Font.getDefaultFont();
    public int foreColor = 0xffffff;
    public int bgColor = 0xcccccc;
    public int selectedBgColor = 0x000000;
    public int selectedForeColor = 0xff0000;

    /* internal 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 CalendarWidget(Date date)
{
    calendar = Calendar.getInstance();

    //we'll see these 2 methods later
    setDate(date);

    initialize();
}
public Date getSelectedDate()
{
    return calendar.getTime();
}
public void setDate(Date d)
{
    currentTimestamp = d.getTime();

    calendar.setTime(d);

    //weeks number can change, depending on week starting day and month total days
    this.weeks = (int)Math.ceil(((double)getStartWeekday() + getMonthDays()) / 7);
}
public void setDate(long timestamp)
{
    setDate(new Date(timestamp));
}
void initialize()
{
    //let's initialize calendar size
    this.cellWidth = font.stringWidth("MM") + 3 * padding;
    this.cellHeight = font.getHeight() + 15 * 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:
        return calendar.get(Calendar.YEAR) % 4 == 0 && calendar.get(Calendar.YEAR) % 100 != 0 ? 29 : 28;
    default:
        return 31;
    }
}
int getStartWeekday()
{
    //let's create a new calendar with same month and year, but with day 1
    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);

    //we must normalize DAY_OF_WEEK returned value
    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 + 86400000 * delta);

    //we have to check if month has changed
    //if yes, we have to recalculate month height
    //since weeks number could be changed
    if(calendar.get(Calendar.MONTH) != prevMonth)
    {
        initHeight();
    }
}
public void paint(Graphics g)
{
    //painting background
    g.setColor(bgColor);
    g.fillRect(0, 0, width, height);

    //painting header (month-year label)
    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);

    //painting week days labels
    g.translate(0, headerHeight);

    g.setColor(weekdayBgColor);
    g.fillRect(0, 0, width, weekHeight);

    g.setColor(weekdayColor);
    g.setFont(weekdayFont);

    for(int i = 0; i < 7; i++)
    {
        g.drawString(WEEKDAY_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 + borderWidth) + padding;


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

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


        if(i + 1 == currentDay)
        {
            g.setColor(foreColor);
        }
    }

    g.translate(0, - headerHeight - weekHeight);
}
}
4

1 回答 1

1

您发布的代码片段中没有明显的错误。

当您的 MIDlet 变得如此复杂时，为了更容易找出可能出现的问题，添加日志语句并在模拟器中运行它并观察控制台输出。

您肯定需要在catch块内添加日志记录。要找出我为什么要做出如此强烈的声明，请在 Web 上搜索Java 燕子异常之类的内容。

我建议记录的其他点是在commandAction调用setCurrent. 在开发时，请随意在您认为需要的地方添加更多内容（keyPressed看起来也是一个不错的候选者）。

public class Log {
    // utility class to keep logging code in one place
    public static void log (String message) {
        System.out.println(message);
        // when debugging at real device, S.o.p above can be refactored
        //  - based on ideas like one used here (with Form.append):
        //    http://stackoverflow.com/questions/10649974
        //  - Another option would be to write log to RMS
        //    and use dedicated MIDlet to read it from there
        //  - If MIDlet has network connection, an option is
        //    to pass log messages over the network. Etc etc...
    }
}


// ... other classes...
    // ...
    catch (Exception e) {
        Log.log("unexpected exception: [" + e + "]");
    }

    // ...
    public void commandAction(Command c, Displayable s) {
        Log.log("command: [" + c.getCommandLabel()
                + "] at screen: [" + d.getTitle() + "]");
        // ...
    }

    // ...
    Log.log("set current: [" + someDisplayable.getTitle() + "]");
    mydisplay.setCurrent(someDisplayable);
    // ...

    protected void keyPressed(int key) {
        Log.log("key pressed: [" + getKeyName(key) + "]");
        // ...
    }
于 2012-05-18T05:59:16.477 回答