question: public static boolean isExtension ( String filename , String extension ) { if ( filename == null ) { return false ; } if ( extension == null || extension . length ( ) == 0 ) { return indexOfExtension ( filename ) == - 1 ; } String fileExt = getExtension ( filename ) ; return fileExt . equals ( extension ) ; }
target:  Checks whether the extension of the filename is that specified. <p> This method obtains the extension as the textual part of the filename after the last dot. There must be no directory separator after the dot. The extension check is case-sensitive on all platforms.