ListChange

This sealed interface describes the possible changes that can happen to a RealmList collection.

The states are represented by the specific subclasses InitialList, UpdatedList and DeletedList. When the list is deleted an empty list is emitted instead of null.

Changes can thus be consumed in a number of ways:

// Variant 1: Switch on the sealed interface
person.addresses.asFlow()
  .collect { listChange: ListChange<Address> ->
      when(listChange) {
         is InitialList -> setAddressesUIList(listChange.list)
         is UpdatedList -> updateAddressesUIList(listChange) // Android RecyclerView knows how to animate ranges
         is DeletedList -> deleteAddressesUIList()
      }
  }


// Variant 2: Just pass on the list
person.addresses.asFlow()
  .collect { listChange: ListChange<Address> ->
      handleChange(listChange.list)
  }

When the list is updated, extra information is provided describing the changes from the previous version. This information is formatted in a way that can be feed directly to drive animations on UI components like RecyclerView. In order to access this information, the ListChange must be cast to the appropriate subclass.

person.addresses.asFlow()
  .collect { listChange: ListChange<Address> ->
      when(listChange) {
         is InitialList -> setList(listChange.list)
         is UpdatedList -> { // Automatic cast to UpdatedList
             updateList(
                 listChange.list,
                 listChange.deletionRanges,
                 listChange.insertionRanges,
                 listChange.changeRanges
            )
         }
         is DeletedList -> deleteList()
      }
  }

Properties

list

abstract val list: RealmList<T>

Inheritors

InitialList

UpdatedList

DeletedList