How are Java source code files named

A Java source code file takes the name of a public class or interface that is defined withinthe file. A sourcecode file may contain at most one public class or interface. If a public class or interface isdefined within asource code file, then the source code file must take the name of the public class orinterface. If no publicclass or interface is defined within a source code file, then the file must take on a namethat is different thanits classes and interfaces. Source code files use the .java extension.