question: private void addMembers ( List < String > newMembers ) { if ( newMembers . isEmpty ( ) ) { return ; } int startIndex = - 1 ; int endIndex = - 1 ; for ( String name : newMembers ) { Member member = new Member ( name ) ; member . setChangeListener ( healthListener ) ; memberMap . put ( name , member ) ; memberList . add ( member ) ; int index = memberList . indexOf ( member ) ; if ( startIndex == - 1 ) { startIndex = index ; endIndex = index ; } else { startIndex = Math . min ( startIndex , index ) ; endIndex = Math . max ( endIndex , index ) ; } } fireIntervalAdded ( this , startIndex , endIndex ) ; }
target:  Add a group of new members.