source code file extension means what??

Answer 1

A file extension, located at the end of the filename, indicates what the file is. For example, a file with .txt is a textfile. The java source code files have the extension .java.

Answer 2

means in which file u save ur coding .. its extension must be .java

Answer 3

Just like Ms Word it's extension is .docx the source file extension of Java is .java