我编写了以下 Java 源文件 ( Hello.java
):
package com;
public class Hello {
public static void main(String[] args) {
System.out.println("Hello!");
}
}
我把这个保存到C:/tmpjava/Hello.java
.
从命令行,我导航到该目录并运行javac Hello.java
. 然后我运行dir
:
Hello.class
Hello.java
然后,从我刚刚运行的同一个目录中javac
,我运行java Hello.class
并得到:
Exception in thread "main" java.lang.NoClassDefFoundError: Hello/class
Caused by: java.lang.ClassNotFoundException: Hello.class
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: Hello.class. Program will exit.
这里发生了什么?!?怎么javac
能跑得好,但不行java
?