用命令端运行java文件抛异常总结

我的java文件路径是：F:/com/test/Aa.java.

1、编译
F:\com\test>javac Aa.java

2、运行
F:\com\test>java Aa
Exception in thread "main" java.lang.NoClassDefFoundError: Aa (wrong name: com/t
est/Aa)
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClassCond(ClassLoader.java:631)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:615)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:14
1)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
        at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
Could not find the main class: Aa.  Program will exit.

F:\com\test>java com.test.Aa
Exception in thread "main" java.lang.NoClassDefFoundError: com/test/Aa
Caused by: java.lang.ClassNotFoundException: com.test.Aa
        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: com.test.Aa.  Program will exit.
F:\com\test>cd ..

F:\com>cd ..

F:\>java com.test.Aa
Hello World!

总结：编译时，要进java类文件的目录下，javac 类.java；运行时，要进入java类文件的包顶级文件层，然后java 包名.类名