question: public static final StringBuilder sprintf0d ( StringBuilder sb , int value , int width ) { long d = value ; if ( d < 0 ) { sb . append ( '-' ) ; d = - d ; -- width ; } int n = 10 ; for ( int i = 2 ; i < width ; i ++ ) { n *= 10 ; } for ( int i = 1 ; i < width && d < n ; i ++ ) { sb . append ( '0' ) ; n /= 10 ; } sb . append ( d ) ; return sb ; }
target:  Mimics sprintf(buf, "%0*d", decaimal, width).