Running a program in Java 8. Where did the bin folders go?

Question

Java

In the project folder, instead of bin and src, there are build and src. Now build is bin, or do I really need cat /dev/ass > /dev/head ?
Apparently, after all, the latter, because on the command line when you try to enter C: \ project name \ bin ru.sitename.programm substituting build instead of bin, cmd gives out Error: Could not find or load main class blabla.
UPD: I figured out the launch by packing the archive into a .jar, now it works from cmd. But nevertheless, the course instructor made me do something with running the class file from cmd without exporting to .jar. Why it didn't work, any ideas?
The calling code was: "java -classpath C:\Eclipse\Helloworld\bin ru.specialist.Programm". Did in accordance with the instructions, the Eclipse folder, respectively, just the name of the folder with the projects.