Java package folders with a dot in the name
classpath, java
Solution
The packaging structure mentioned at the top of the class file has less to do with compilation and more to do with Runtime class loading.
You can put any packagename and compile it. e.g. following java class compiles
package com.sa.test.me.yes.no;
public class Test{
public static void main(String[] args){
System.out.println("Hello");
}
}
It compiles even if you don't put inside a folder structure same as package declaration. You can test it by not putting in any folder (e.g `java Test.java`)
2 . Packages organization is more important while class loading. The classloader will always search for the class into the folder based on package structure. So when you are trying to run your program, the classloader tries to search for the class file in a folder as per the package structure.
Problem
Is it by spec that, given a `MyClass.java` file containing ``` package com.mycorp.foo; public class MyClass { public static void main (String[] args) { System.out.println("Hello, world!"); } } ``` in the following path (note the dot in the folder name): ``` ./com/mycorp.foo/MyClass.java ``` the following works fine: ``` $ javac com/mycorp.foo/MyClass.java ``` producing `./com/mycorp.foo/MyClass.class` while this doesn't work: ``` $ java com.mycorp.foo.MyClass Exception in thread "main" java.lang.NoClassDefFoundError: com/mycorp/foo/MyClass Caused by: java.lang.ClassNotFoundException: com.mycorp.foo.MyClass 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) ```