question: public MP3Reader ( File file ) throws FileNotFoundException { this . file = file ; fis = new FileInputStream ( file ) ; channel = fis . getChannel ( ) ; try { mappedFile = channel . map ( FileChannel . MapMode . READ_ONLY , 0 , channel . size ( ) ) ; } catch ( IOException e ) { log . error ( "MP3Reader {}" , e ) ; } mappedFile . order ( ByteOrder . BIG_ENDIAN ) ; in = IoBuffer . wrap ( mappedFile ) ; analyzeKeyFrames ( ) ; firstTags . addFirst ( createFileMeta ( ) ) ; if ( in . remaining ( ) > 4 ) { searchNextFrame ( ) ; int pos = in . position ( ) ; MP3Header header = readHeader ( ) ; in . position ( pos ) ; if ( header != null ) { checkValidHeader ( header ) ; } else { throw new RuntimeException ( "No initial header found." ) ; } } }
target:  Creates reader from file input stream