question: public static int indexOfJavaLikeExtension ( String fileName ) { int fileNameLength = fileName . length ( ) ; char [ ] [ ] javaLikeExtensions = getJavaLikeExtensions ( ) ; extensions : for ( int i = 0 , length = javaLikeExtensions . length ; i < length ; i ++ ) { char [ ] extension = javaLikeExtensions [ i ] ; int extensionLength = extension . length ; int extensionStart = fileNameLength - extensionLength ; int dotIndex = extensionStart - 1 ; if ( dotIndex < 0 ) continue ; if ( fileName . charAt ( dotIndex ) != '.' ) continue ; for ( int j = 0 ; j < extensionLength ; j ++ ) { if ( fileName . charAt ( extensionStart + j ) != extension [ j ] ) continue extensions ; } return dotIndex ; } return - 1 ; }
target:  Returns the index of the Java like extension of the given file name or -1 if it doesn't end with a known Java like extension. Note this is the index of the '.' even if it is not considered part of the extension.