question: public static String toBits ( final long x ) { final StringBuilder sb = new StringBuilder ( ) ; long t = x ; boolean first = false ; for ( int i = 0 ; i < 64 ; i ++ ) { if ( t < 0 ) { sb . append ( "1" ) ; first = true ; } else if ( first ) { sb . append ( "0" ) ; } t = t << 1 ; } assert t == 0 ; return sb . toString ( ) ; }
target:  Convert a number into a bit string.