question: private void updateChanges ( DocumentEvent event , StringBuilder oldText ) { int i = findIndex ( event . getOffset ( ) ) ; int endOffset = event . getOffset ( ) + event . getNewLength ( ) ; TextChangeImpl change = new TextChangeImpl ( oldText , event . getOffset ( ) , endOffset ) ; if ( i < 0 ) { myChanges . add ( change ) ; } else { myChanges . add ( i , change ) ; } }
target:  Updates current object's state on the basis of the given event assuming that there are no stored change ranges that start after offset denoted by the given event.