mac 电脑

问题复现

随手写了一个main方法，想用命令行操作

进入 BlockDemo.java 所在目录：

wn@wangnandeMBP wn % cd /Users/wn/IdeaProjects/test/JianZhiOffer/src/main/java/com/io/wn
wn@wangnandeMBP wn % ls -l
total 16
-rw-r--r--  1 wangnan  staff  537  7 14 17:59 BlockDemo.java
drwxr-xr-x  4 wangnan  staff  128  7 14 17:59 aio
drwxr-xr-x  4 wangnan  staff  128  7 14 17:59 bio
drwxr-xr-x  4 wangnan  staff  128  7 14 18:10 nio

编译 BlockDemo.java，生成字节码文件 BlockDemo.class

wn@wangnandeMBP wn % javac BlockDemo.java
wn@wangnandeMBP wn % ls -l
total 16
-rw-r--r--  1 wangnan  staff  823  7 14 19:23 BlockDemo.class
-rw-r--r--  1 wangnan  staff  537  7 14 17:59 BlockDemo.java
drwxr-xr-x  4 wangnan  staff  128  7 14 17:59 aio
drwxr-xr-x  4 wangnan  staff  128  7 14 17:59 bio
drwxr-xr-x  4 wangnan  staff  128  7 14 18:10 nio
wn@wangnandeMBP wn % java BlockDemo
错误: 找不到或无法加载主类 BlockDemo

运行字节码文件 BlockDemo.class ，突然报错误: 找不到或无法加载主类 BlockDemo

wn@wangnandeMBP wn % java BlockDemo
错误: 找不到或无法加载主类 BlockDemo

解决方案：

项目的class文件是统一放到target下面，需要再target的class目录下执行运行操作才行

1. 先执行compile编译，生成class文件
   
2. 进入target的class目录下执行运行操作

wn@wangnandeMBP bio % cd /Users/wangnan/IdeaProjects/test/JianZhiOffer/target/classes
wn@wangnandeMBP classes % pwd
/Users/wangnan/IdeaProjects/test/JianZhiOffer/target/classes
wn@wangnandeMBP classes % java com.io.wn.BlockDemo
请输入一个字符串:
success
你输入的字符串是: success