请教J2ME编程前辈，谢谢^_^

安装了jdk1.6.0_02
WTK2.5.2
NEC_N820

环境变量配置如下：PATH    .;C:\Program Files\Java\jdk1.6.0_02\bin
                CLASSPATH    .;C:\Program Files\Java\jre1.6.0_02\lib\rt.jar

NEC_N820配置如下：JDK Path  C:\Program Files\Java\jdk1.6.0_02
                MIDP Path  C:\WTK2.5.2

程序代码如下：
import javax.microedition.midlet.MIDlet;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.TextBox;

/**
* HelloWorld
*
*/

public class HelloWorld extends MIDlet {
private Display display;
private TextBox textbox;

public HelloWorld() {
display = Display.getDisplay(this);
textbox = new TextBox("HelloWorld.", 500, 0);
}

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

public void pauseApp() {
}

public void destroyApp(boolean unconditional) {
}
}


编译错误如下：

致命错误：在类路径或引导类路径中找不到软件包 java.lang
Compiled with options:
WARNING:  set options to -g:none for final build.

是不是插件没安好哦