question: public final void write ( String s , int off , int len ) throws IOException { if ( bufferSize == 0 ) { writer . write ( s , off , len ) ; return ; } int b = off , t = off + len ; while ( b < t ) { int d = min ( bufferSize - nextChar , t - b ) ; s . getChars ( b , b + d , cb , nextChar ) ; b += d ; nextChar += d ; if ( nextChar >= bufferSize ) if ( autoFlush ) flushBuffer ( ) ; else bufferOverflow ( ) ; } }
target:  Write a portion of a String.