While trying to execute java code via command-line you may have encountered the above error quite commonly (if you declare your class as a part of some package)
Packages are containers for classes that are used to keep the class name space compartmentalized. For example, a package allows you to create a class named List, which you can store in your own package without concern that it will collide with some other class named List stored elsewhere.
How does the Java run-time system know where to look for packages that you create?
The answer has three parts. First, by default, the Java run-time system uses the current working directory as its starting point. Thus, if your package is in a subdirectory of the current directory, it will be found. Second, you can specify a directory path or paths by setting the CLASSPATH environmental variable. Third, you can use the -classpath option with java and javac to specify the path to your classes.
In this read I will focus on the most easiest way, i.e. first one
1> Checkin into your development directory in my case this is
2> The easiest way is to simply create your package directory below your development folder.
3> Now put your .java file into the package directory complie the code .
CAUTION: make sure that all the .class files are placed in the right folder/directory.
4> Then execute the class using the command:
and that's that. :)