question: public static String toBits ( final long x ) { final StringBuilder sb = new StringBuilder ( ) ; long t = x ; for ( int i = 0 ; i < 64 ; i ++ ) { if ( ( i & 7 ) == 0 && i > 0 ) { sb . append ( ":" ) ; } sb . append ( t < 0 ? "1" : "0" ) ; t = t << 1 ; } assert t == 0 ; return sb . toString ( ) ; }
target:  Convert a number into a bit string with separators between each group of 8.