question: private void appendToBuf ( char [ ] ch , int start , int end ) { if ( start == end ) { return ; } int neededBufLen = pos + ( end - start ) ; if ( neededBufLen > buf . length ) { char [ ] newBuf = new char [ neededBufLen ] ; System . arraycopy ( buf , 0 , newBuf , 0 , pos ) ; if ( bufHolder == null ) { bufHolder = buf ; } buf = newBuf ; } System . arraycopy ( ch , start , buf , pos , end - start ) ; pos += ( end - start ) ; }
target:  Appends a slice of an UTF-16 code unit array to the internal  buffer.