界面跳转

[gesanri]

要实现的功能很简单，但总是有问题，麻烦大家看看
首先，主界面：
武汉特色介绍

景点
小吃/小吃街
购物街
。。。

完后点击景点，进入子界面：
黄鹤楼
中山公园
江滩

到此我都实现了，下一步，我点击黄鹤楼，就显示一段描述黄鹤楼的文字，这个位置总报错，程序如下（其中DivPage.java单独运行是可以的，所以错误应该在Main.java）：

Main.java

package wuhan; 

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

public class Main extends MIDlet implements CommandListener{ 
private Display display; 
private Form form; 
private Command exit; 
private Command process; 
private ChoiceGroup characters; 
private ChoiceGroup cg; 
private int characterIndex; 
private TestCanvas canvas;

public Main() { 
	display = Display.getDisplay(this); 
	characters = new ChoiceGroup("武汉特色介绍",Choice.EXCLUSIVE); 
	characters.append("景点", null); 
	characters.append("小吃/小吃街", null); 
	characters.append("购物街", null); 
	characters.append("大型购物商场", null); 
	characters.append("大型购物超市", null); 
	characters.append("大学院校", null); 
	exit = new Command("Exit",Command.EXIT,1); 
	process = new Command("Process",Command.SCREEN,2); 
	form = new Form(""); 
	characterIndex = form.append(characters); 
	form.addCommand(exit); 
	form.addCommand(process); 
	form.setCommandListener(this); 
} 

	public void startApp(){ 
        display.setCurrent(form); 
    } 
    
    public void pauseApp(){ 
    } 

    public void destroyApp(boolean arg0){ 
    } 
    
    public void commandAction(Command command,Displayable displayable){ 
	    if(command==exit){ 
	        destroyApp(true); 
	        notifyDestroyed(); 
	    } 
	    else if(command==process){
	    	int x=0;
		    boolean picks[] = new boolean[characters.size()]; 
		    characters.getSelectedFlags(picks); 
		    for(;x <picks.length;x++){ 
			    if(picks[x]){ 
				    cg = new ChoiceGroup("",Choice.EXCLUSIVE); 
				    switch(x){ 
					    case 0: cg.append("黄鹤楼", null); 
					            cg.append("中山公园", null); 
					            cg.append("江滩", null); 
					            break; 
					    case 1: cg.append("热干面", null); 
					            cg.append("豆皮", null); 
					            break; 
					    case 2: 
					    case 3: 
					    case 4: 
					    case 5: break; 
					    default: break; 
				    }
				    break;
			    } 
		  } 
		  form.delete(characterIndex); 
		  characterIndex = form.append(cg); 
		  boolean picks2[] = new boolean[cg.size()];
		  cg.getSelectedFlags(picks2);
		  if(x==0){
			  for(int y=0;y<picks2.length;y++){
				  if(picks2[y]){
					  switch(y){
					  	case 0: canvas = new TestCanvas(new DivPage());
					  		    display.setCurrent(canvas);
					  	        break;
					  	default: break;
					  }
				  }
			  }
		  }
		  form.delete(characterIndex); 
	    }
    } 
} 

DivPage.java

package wuhan;

import javax.microedition.lcdui.Canvas;
import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.Font;
import javax.microedition.lcdui.Graphics;
import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;

public class DivPage extends MIDlet {
    private Display display;

    private TestCanvas canvas;

    public DivPage() {
        display = Display.getDisplay(this);
        canvas = new TestCanvas(this);
    }

    protected void startApp() throws MIDletStateChangeException {
        display.setCurrent(canvas);
    }

    protected void pauseApp() {

    }

    protected void destroyApp(boolean arg0) {

    }

    public void exitMIDlet() {
        destroyApp(true);
        notifyDestroyed();
    }
}

    class TestCanvas extends Canvas implements CommandListener {
        private String text = "                            武汉特色介绍"
                + "\n一、 景点"
                + "\n1、 黄鹤楼"
                + "\n        冲决巴山群峰，接纳潇湘云水，浩荡长江在三楚腹地与其最长支流汉水交汇，造就了武汉隔两江而三镇互峙的伟姿。 这里地处江汉平原东缘，鄂东南丘陵余脉起伏于平野湖沼之间，龟蛇两山相夹，江上舟辑如织黄鹤楼天造地设于斯。"
                + "\n        黄鹤楼是古典与现代熔铸、诗化与美意构筑的精品。她处在山川灵气动荡吐钠的交点，正好映和中华民族喜好登高的民风民俗、亲近自然的空间意识、崇尚宇宙的哲学观念。登黄鹤楼，不仅仅获得愉快，更能使心灵与宇宙意象互渗互融，从而使心灵净化。这大约就是黄鹤楼美的魅力经风雨而不衰，与日月共长存原因之所在。"
                + "\n        巍峨耸立于武昌蛇山的黄鹤楼，享有“天下绝景”的盛誉，与湖南岳阳楼，江西滕王阁并称为“江南三大名楼”。唐代诗人崔颢一首“昔人已乘黄鹤去，此地空余黄鹤楼。黄鹤一去不复返，白云千载空悠悠。晴川历历汉阳树，芳草萋萋鹦鹉洲。日暮乡关何处是，烟波江上使人愁。”已成为千古绝唱，更使黄鹤楼名声大噪。全楼各层布置有大型壁画、楹联、文物等。楼外铸铜黄鹤造型、胜像宝塔、牌坊、轩廊、亭阁等一批辅助建筑，将主楼烘托得更加壮丽。登楼远眺，“极目楚天舒”，不尽长江滚滚来，三镇风光尽收眼底。";

        private int sreenWidth;

        private int sreenHeight;

        private int scrollHeight;

        private int scrollY;

        private int regionY;

        private int numHeight;

        private Command exit;

        private DivPage divPage;

        public TestCanvas(DivPage divPage) {
            this.divPage = divPage;
            exit = new Command("Exit", Command.EXIT, 1);
            addCommand(exit);
            setCommandListener(this);
            try {
                this.sreenHeight = this.getHeight();
                this.sreenWidth = this.getWidth();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

        protected void paint(Graphics g) {
            g.setColor(0xFFFFFF);
            g.fillRect(0, 0, this.sreenWidth, this.sreenHeight);
            Font font = g.getFont();
            g.setColor(0x00000);
            int row = drawWrapString(g, text, 0, regionY, sreenWidth - 18, font);
            if (this.numHeight == 0)
                this.numHeight = (row + 1) * font.getHeight();
            System.out.println("numHeigth=" + numHeight);
            this.scrollHeight = this.sreenHeight * this.sreenHeight / numHeight;
            this.scrollY = (-this.regionY) * this.sreenHeight / numHeight;
            g.setColor(255);
            g.fillRect(this.sreenWidth - 6, 0, 6, this.sreenHeight);
            g.setColor(0xFFFFFF);
            g.fillRect(this.sreenWidth - 5, this.scrollY, 4, this.scrollHeight);
        }

        public void keyPressed(int keyCode) {
            System.out.println(keyCode);
            System.out.println(sreenHeight);
            if (keyCode == -2) {
                if (this.sreenHeight - this.regionY >= this.numHeight)
                    return;
                this.regionY -= 30;
            } else if (keyCode == -1) {
                if (this.regionY >= 0)
                    return;
                this.regionY += 30;
            }
            this.repaint();
        }

        public void commandAction(Command command, Displayable displayable) {
            if (command == exit)
                divPage.exitMIDlet();
        }
    

        public static int drawWrapString(Graphics g, String str, int x, int y,
            int rightMargin, Font font) {
        int row = 0;
        int leftMargin = x;
        int fW = 0;
        int fH = font.getHeight();
        char c;
        for (int i = 0; i < str.length(); i++) {
            c = str.charAt(i);
            if (c == '\r')
                continue;
            fW = font.charWidth(c);

            if (c == '\n' || (x + fW) > rightMargin) {
                x = leftMargin; 
                y += fH; 
                row++;
            }

            if (c != '\n') {
                g.drawChar(c, x, y, 20);
                x += fW; 
            }

        }
        return row;
    }
}

[kf156]

J2ME不允许一个MIDlet调用另一个MIDlet
所以改后只留下一个MIDlet类。

Main.java

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

public class Main extends MIDlet implements CommandListener {
	public Display display;
	private Form form;
	private Command exit;
	private Command process;
	private ChoiceGroup characters;
	private ChoiceGroup cg;
	private int characterIndex;
	private TestCanvas canvas;
	public static Main instance;

	public Main() {
		instance = this;
		display = Display.getDisplay(this);
		characters = new ChoiceGroup("武汉特色介绍", Choice.EXCLUSIVE);
		characters.append("景点", null);
		characters.append("小吃/小吃街", null);
		characters.append("购物街", null);
		characters.append("大型购物商场", null);
		characters.append("大型购物超市", null);
		characters.append("大学院校", null);
		exit = new Command("Exit", Command.EXIT, 1);
		process = new Command("Process", Command.SCREEN, 2);
		form = new Form("");
		characterIndex = form.append(characters);
		form.addCommand(exit);
		form.addCommand(process);
		form.setCommandListener(this);
	}

	public void startApp() {
		display.setCurrent(form);
	}

	public void pauseApp() {
	}

	public void destroyApp(boolean arg0) {
	}

	public static void exit() {
		instance.destroyApp(true);
		instance.notifyDestroyed();
		instance = null;
	}

	public void commandAction(Command command, Displayable displayable) {
		if (command == exit) {
			exit();
		} else if (command == process) {
			int x = 0;
			boolean picks[] = new boolean[characters.size()];
			characters.getSelectedFlags(picks);
			for (; x < picks.length; x++) {
				if (picks[x]) {
					cg = new ChoiceGroup("", Choice.EXCLUSIVE);
					switch (x) {
					case 0:
						cg.append("黄鹤楼", null);
						cg.append("中山公园", null);
						cg.append("江滩", null);
						break;
					case 1:
						cg.append("热干面", null);
						cg.append("豆皮", null);
						break;
					case 2:
					case 3:
					case 4:
					case 5:
						break;
					default:
						break;
					}
					break;
				}
			}
			form.delete(characterIndex);
			characterIndex = form.append(cg);
			boolean picks2[] = new boolean[cg.size()];
			cg.getSelectedFlags(picks2);
			if (x == 0) {
				for (int y = 0; y < picks2.length; y++) {
					if (picks2[y]) {
						switch (y) {
						case 0:
							canvas = new TestCanvas();
							display.setCurrent(canvas);
							break;
						default:
							break;
						}
					}
				}
			}
			form.delete(characterIndex);
		}
	}
}

TestCanvas.java

import javax.microedition.lcdui.Canvas;
import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.Font;
import javax.microedition.lcdui.Graphics;

public class TestCanvas extends Canvas implements CommandListener {
	private String text = "                            武汉特色介绍"
			+ "\n一、 景点"
			+ "\n1、 黄鹤楼"
			+ "\n        冲决巴山群峰，接纳潇湘云水，浩荡长江在三楚腹地与其最长支流汉水交汇，造就了武汉隔两江而三镇互峙的伟姿。 这里地处江汉平原东缘，鄂东南丘陵余脉起伏于平野湖沼之间，龟蛇两山相夹，江上舟辑如织黄鹤楼天造地设于斯。"
			+ "\n        黄鹤楼是古典与现代熔铸、诗化与美意构筑的精品。她处在山川灵气动荡吐钠的交点，正好映和中华民族喜好登高的民风民俗、亲近自然的空间意识、崇尚宇宙的哲学观念。登黄鹤楼，不仅仅获得愉快，更能使心灵与宇宙意象互渗互融，从而使心灵净化。这大约就是黄鹤楼美的魅力经风雨而不衰，与日月共长存原因之所在。"
			+ "\n        巍峨耸立于武昌蛇山的黄鹤楼，享有“天下绝景”的盛誉，与湖南岳阳楼，江西滕王阁并称为“江南三大名楼”。唐代诗人崔颢一首“昔人已乘黄鹤去，此地空余黄鹤楼。黄鹤一去不复返，白云千载空悠悠。晴川历历汉阳树，芳草萋萋鹦鹉洲。日暮乡关何处是，烟波江上使人愁。”已成为千古绝唱，更使黄鹤楼名声大噪。全楼各层布置有大型壁画、楹联、文物等。楼外铸铜黄鹤造型、胜像宝塔、牌坊、轩廊、亭阁等一批辅助建筑，将主楼烘托得更加壮丽。登楼远眺，“极目楚天舒”，不尽长江滚滚来，三镇风光尽收眼底。";

	private int sreenWidth;

	private int sreenHeight;

	private int scrollHeight;

	private int scrollY;

	private int regionY;

	private int numHeight;

	private Command exit;

	public TestCanvas() {
		exit = new Command("Exit", Command.EXIT, 1);
		addCommand(exit);
		setCommandListener(this);
		try {
			this.sreenHeight = this.getHeight();
			this.sreenWidth = this.getWidth();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	protected void paint(Graphics g) {
		g.setColor(0xFFFFFF);
		g.fillRect(0, 0, this.sreenWidth, this.sreenHeight);
		Font font = g.getFont();
		g.setColor(0x00000);
		int row = drawWrapString(g, text, 0, regionY, sreenWidth - 18, font);
		if (this.numHeight == 0)
			this.numHeight = (row + 1) * font.getHeight();
		System.out.println("numHeigth=" + numHeight);
		this.scrollHeight = this.sreenHeight * this.sreenHeight / numHeight;
		this.scrollY = (-this.regionY) * this.sreenHeight / numHeight;
		g.setColor(255);
		g.fillRect(this.sreenWidth - 6, 0, 6, this.sreenHeight);
		g.setColor(0xFFFFFF);
		g.fillRect(this.sreenWidth - 5, this.scrollY, 4, this.scrollHeight);
	}

	public void keyPressed(int keyCode) {
		System.out.println(keyCode);
		System.out.println(sreenHeight);
		if (keyCode == -2) {
			if (this.sreenHeight - this.regionY >= this.numHeight)
				return;
			this.regionY -= 30;
		} else if (keyCode == -1) {
			if (this.regionY >= 0)
				return;
			this.regionY += 30;
		}
		this.repaint();
	}

	public void commandAction(Command command, Displayable displayable) {
		if (command == exit)
			Main.exit();
		// divPage.exitMIDlet();
	}

	public static int drawWrapString(Graphics g, String str, int x, int y,
			int rightMargin, Font font) {
		int row = 0;
		int leftMargin = x;
		int fW = 0;
		int fH = font.getHeight();
		char c;
		for (int i = 0; i < str.length(); i++) {
			c = str.charAt(i);
			if (c == '\r')
				continue;
			fW = font.charWidth(c);

			if (c == '\n' || (x + fW) > rightMargin) {
				x = leftMargin;
				y += fH;
				row++;
			}

			if (c != '\n') {
				g.drawChar(c, x, y, 20);
				x += fW;
			}

		}
		return row;
	}
}

[gesanri]

改了后，昨天的问题解决了，但新的问题又出现了，点击景点直接显示那段描述黄鹤楼的文字了，中间界面：
黄鹤楼
中山公园
江滩
没有显示出来，如何在form.append(cg)后停顿一下，显示当前界面啊

[kf156]

分两个命令就好了。

package gesanri;

import java.util.Timer;
import java.util.TimerTask;

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

public class Main extends MIDlet implements CommandListener {
	public Display display;

	private Form form;

	private Command exit;

	private Command process;

	private Command enter;

	private Command back;

	private ChoiceGroup characters;

	private ChoiceGroup cg;

	private int characterIndex;

	private TestCanvas canvas;

	public static Main instance;

	public Main() {
		instance = this;
		display = Display.getDisplay(this);
		characters = new ChoiceGroup("武汉特色介绍", Choice.EXCLUSIVE);
		characters.append("景点", null);
		characters.append("小吃/小吃街", null);
		characters.append("购物街", null);
		characters.append("大型购物商场", null);
		characters.append("大型购物超市", null);
		characters.append("大学院校", null);
		exit = new Command("Exit", Command.EXIT, 1);
		process = new Command("Process", Command.SCREEN, 2);
		enter = new Command("Enter", Command.SCREEN, 1);
		back = new Command("Back", Command.BACK, 2);
		form = new Form("");
		characterIndex = form.append(characters);
		form.addCommand(exit);
		form.addCommand(process);
		form.setCommandListener(this);
	}

	public void startApp() {
		display.setCurrent(form);
	}

	public void pauseApp() {
	}

	public void destroyApp(boolean arg0) {
	}

	public static void exit() {
		instance.destroyApp(true);
		instance.notifyDestroyed();
		instance = null;
	}

	public void commandAction(Command command, Displayable displayable) {
		if (command == exit) {
			exit();
		} else if (command == process) {
			cg = new ChoiceGroup("", Choice.EXCLUSIVE);
			switch (characters.getSelectedIndex()) {
			case 0:
				cg.append("黄鹤楼", null);
				cg.append("中山公园", null);
				cg.append("江滩", null);
				break;
			case 1:
				cg.append("热干面", null);
				cg.append("豆皮", null);
				break;
			case 2:
			case 3:
			case 4:
			case 5:
				break;
			default:
				break;
			}
			// }
			form.removeCommand(process);
			form.removeCommand(exit);
			form.deleteAll();
			// form.delete(characterIndex);
			characterIndex = form.append(cg);
			form.addCommand(enter);
			form.addCommand(back);

		} else if (command == enter) {
			switch (cg.getSelectedIndex()) {
			case 0:
				canvas = new TestCanvas();
				display.setCurrent(canvas);
				break;
			default:
				break;
			}

		} else if (command == back) {
			form.removeCommand(enter);
			form.removeCommand(back);
			form.deleteAll();
			form.append(characters);
			form.addCommand(exit);
			form.addCommand(process);
		}

	}
}

[gesanri]

真是高手啊，你觉得我这种程序结构是不是有问题啊，因为我现在这只放了很少的信息进去，实际要开发的程序景点，小吃/小吃街，购物街，商场，超市这些目录下都有很多的内容，甚至还有子目录，这样都加进去的话，我的Main.class是不是太庞大了，不符合软件开发的基本要求吧

[老张-AI]

[Quote=引用 3 楼 kf156 的回复:]
分两个命令就好了。

Java codepackage gesanri;import java.util.Timer;import java.util.TimerTask;import javax.microedition.midlet.*;import javax.microedition.lcdui.*;publicclass Mainextends MIDletimplements CommandListener {public Display display;private Form form;private Command exit;private Command process;private Command enter;private Command back;private ChoiceGroup characters;private ChoiceGroup cg;privateint characterIndex;private TestCanvas canvas;publicstatic Main instance;public Main() {
instance=this;
display= Display.getDisplay(this);
characters=new ChoiceGroup("武汉特色介绍", Choice.EXCLUSIVE);
characters.append("景点",null);
characters.append("小吃/小吃街",null);
characters.append("购物街",null);
characters.append("大型购物商场",null);
characters.append("大型购物超市",null);
characters.append("大学院校",null);
exit=new Command("Exit", Command.EXIT,1);
process=new Command("Process", Command.SCREEN,2);
enter=new Command("Enter", Command.SCREEN,1);
back=new Command("Back", Command.BACK,2);
form=new Form("");
characterIndex= form.append(characters);
form.addCommand(exit);
form.addCommand(process);
form.setCommandListener(this);
}publicvoid startApp() {
display.setCurrent(form);
}publicvoid pauseApp() {
}publicvoid destroyApp(boolean arg0) {
}publicstaticvoid exit() {
instance.destroyApp(true);
instance.notifyDestroyed();
instance=null;
}publicvoid commandAction(Command command, Displayable displayable) {if (command== exit) {
exit();
}elseif (command== process) {
cg=new ChoiceGroup("", Choice.EXCLUSIVE);switch (characters.getSelectedIndex()) {case0:
cg.append("黄鹤楼",null);
cg.append("中山公园",null);
cg.append("江滩",null);break;case1:
cg.append("热干面",null);
cg.append("豆皮",null);break;case2:case3:case4:case5:break;default:break;
}// } form.removeCommand(process);
form.removeCommand(exit);
form.deleteAll();// form.delete(characterIndex); characterIndex= form.append(cg);
form.addCommand(enter);
form.addCommand(back);

}elseif (command== enter) {switch (cg.getSelectedIndex()) {case0:
canvas=new TestCanvas();
display.setCurrent(canvas);break;default:break;
}

}elseif (command== back) {
form.removeCommand(enter);
form.removeCommand(back);
form.deleteAll();
form.append(characters);
form.addCommand(exit);
form.addCommand(process);
}

}
}
[/Quote]
高手 学习了

[kf156]

你说的那信息是存在JAR包里，还是从服务端取的？

[gesanri]

那些信息应该是以字符串的形式直接都放在程序中的，不用文件，所以应该是都在jar包里，不从服务器端取，我的问题是因为我主界面就有6个选项，包括景点，小吃/小吃街，超市等等，这些选项又有子目录，比如景点有黄鹤楼，江滩等等，完后有的选项甚至还有子目录，比如超市下面有中百超市，中百超市下面还有武昌中百超市，汉口中百超市等等，选择其中任意一个，都会显示一段描述性的文字，所以整个目录结构很庞大，我这只是先写了极少数的几个所以还看不出来，如果照我这种结构写下去的话，我的Main.class是不是太庞大了，结构似乎不大合理啊

[kf156]

之前也有公司做过类似的项目，后来...
咳，不看好...

言归正传，如果说是以字符串形式存到程序中的话
那肯定不能说直接代码写死有没有下一级目录，而是要通过程序自动识别添加
还有就是如果每个目录都以一个界面来展示的话，当级数比较多的时候，用户会很烦的。

[gesanri]

。。。 程序自动识别添加目录，这对我来说太难了，有没有具体例子，没有也算了

[kf156]

想了好久，数据存代码里，我还真不知道怎么举例。
先抛开数据存哪
说下自动生成目录的思路吧：你理解成HTML页面就比较容易了
首次从index.html页面里得到目录列表，每个目录列表有自己对应的跳转页面地址
选中目录里的某一项，进入。
根据得到对应的页面地址，读取相应页面的内容
判断当前页面里是否还有下级目录？有，展示下级目录:没有，展示当前内容

[gesanri]

呵呵，算了，等我到了那步再说，先用笨方法吧

[lj2008525]

呵呵，

[yangtou]

我用C#写界面有一个父页面和8子页面，现在能实现点击父页面上的按钮进入相应的子页面，但是我实现不了子页面之间的跳转 高手帮帮忙~