java命令行下运行class文件

今天碰到了一个很变态的问题，写了一个很简单的HelloWord.java，内容如下：
package com.yanjiuyanjiu;
public class HelloWorld {
    public static void main(String args[]) {
        System.out.println("Hello World!");
    }
}
在eclipse中运行是可以的，但是在命令行下运行总是失败。我的工程位置为 d:\workspace\HelloWorld\。
尝试了很多次，如下
d:\workspace\HelloWorld\bin\com\yanjiuyanjiu\>java HelloWorld
Exception in thread "main" java.lang.NoClassDefFoundError: HelloWorld (wrong name: com/yanjiuyanjiu/HelloWorld)
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClassCond(Unknown Source)
    at java.lang.ClassLoader.defineClass(Unknown Source)
    at java.security.SecureClassLoader.defineClass(Unknown Source)
    at java.net.URLClassLoader.defineClass(Unknown Source)
    at java.net.URLClassLoader.access$000(Unknown Source)
    at java.net.URLClassLoader$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
Could not find the main class: HelloWorld.  Program will exit.
Exception in thread "main"
d:\workspace\HelloWorld\bin\com\yanjiuyanjiu\>java -classpath .; HelloWorld
Exception in thread "main" java.lang.NoClassDefFoundError: HelloWorld (wrong name: com/yanjiuyanjiu/HelloWorld)
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClassCond(Unknown Source)
    at java.lang.ClassLoader.defineClass(Unknown Sourc