按照教程安装了 jdk，nodejs 和 android sdk，maven。
在命令行输入 java -version 提示 java version "1.6.0_43"
但是输入 mvn -version 提示

C:\Users\dengyi>mvn -version
Exception in thread "main" java.lang.NoClassDefFoundError: –Xmx512m
Caused by: java.lang.ClassNotFoundException: –Xmx512m
at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
Could not find the main class: 鈥揦 mx512m. Program will exit.

这个问题搞了很久了，麻烦哪位高手帮忙看看，谢谢了