初学J2ME,装了 JB9+WTK2.0....运行书中一代码出现异常..帮忙....

[MPU]

JB 9 + WTK2.0
最基本的程序可以运行...

出现异常代码如下:
import javax.microedition.lcdui.*;
import javax.microedition.midlet.*;
public class GraphicsTestCanvas1 extends Canvas
{
public void paint(Graphics g)
{
g.setColor(255,250,0);
//g.setGrayScale(4);
g.fillRect(0,0,getWidth(),getHeight());
int color = g.getColor() ;
int displaycolor = g.getDisplayColor(g.getColor()) ;
System.out.println("目前画面的颜色为："+Integer.toHexString(color));
System.out.println("目前画面的红色为："+g.getRedComponent());
System.out.println("目前画面的绿色为："+g.getGreenComponent());
System.out.println("目前画面的蓝色为："+g.getBlueComponent());
System.out.println("目前画面的显示颜色为："+Integer.toHexString(displaycolor));
System.out.println("画面为："+g.getGrayScale()+"灰度");
}
}
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\Exception\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\
C:\WTK20\bin\emulator.exe -classpath "D:\Save\JAVA\wtk_006\classes;" -Xdevice:DefaultColorPhone -Xdescriptor:"D:\Save\JAVA\wtk_006\jad-temp\GraphicsTestCanvas1.jad"
Running with storage root DefaultColorPhone
Unable to create MIDlet GraphicsTestCanvas1
java.lang.InstantiationException: Class not a MIDlet
at com.sun.midp.midlet.MIDletState.createMIDlet(+51)
at com.sun.midp.midlet.Selector.run(+22)

[zealVampire]

Class not a MIDlet
你首先要是个MIDlet啊

[feiyunjian]

没有创建MIDlet类，而且我看起来连线程都没有。。。。。。。。

[chengfeng]

o, midlet

[chengfeng]

需要一个作为main class的midlet

[王旺旺旺]

另外再建立一个class，应该是如下格式的：

public class MyMIDlet extends MIDlet
{
protected void startApp()
{
}
protected void pauseApp()
{
}
protected void destroyApp(boolean unconditional)
{
}
}

[MPU]

import javax.microedition.lcdui.*;
import javax.microedition.midlet.*;
public class MyMIDlet extends MIDlet
{
private Display display;
public MyMIDlet()
{
display = Display.getDisplay(this);
}
protected void startApp()
{
GraphicsTestCanvas c = new GraphicsTestCanvas();
display.setCurrent(c);
}
protected void pauseApp()
{
}
protected void destroyApp(boolean unconditional)
{
}
}
/////搞定