SOure File declaration rules.
Source file declaration have a may rules for thedeclaring class ,import statement ,and packages statements :
> Here only ne public class for the each source code file.
> comments lways apperas only in beginning or end of any sourse code line.
> must match the publicj class anme and file name.
> the package statement must be the first line in a source code file.
> must be import statement go b/w in the package statement and class declaration.
> impot and packages they must apply to all classes with in the source file.
> A file can have more than one non public class.