I have a lib directory with a thousand jars, where main.jar contains the main method, and the class that contains the main method is org.test.Main.
The directory structure is as follows:

# tree
.
└── lib
    ├── a.jar
    ├── b.jar
    ├── c.jar
    └── main.jar

and now I use these commands to run the message class not found error

# class not found
java -cp lib org.test.Main

# class not found
java -cp lib/*.jar org.test.Main

# class not found
java -cp lib/* org.test.Main

# class not found, 
export CLASSPATH=/mydir/lib
java org.test.Main
unset CLASSPATH

and the follow commands work fine, It seems that the jar in which the main class resides must be specified separately in the classpath

# work fine
java -cp lib/*:lib/main.jar org.test.Main

# work fine, the order is not the question
java -cp lib/main.jar:lib/* org.test.Main

# work fine, list every jar
java -cp lib/main.jar:lib/a.jar::lib/b.jar:lib/c.jar org.test.Main

it looks weird. is there any java specification introduce how the classpath work?

I’m confused about how the java classpath works, and i wonder how it works.