Package com.amazonaws.services.dynamodbv2.datamodeling

Class PaginatedList<T>

  • Type Parameters:
    T - The domain object type stored in this list.
    All Implemented Interfaces:
    Iterable<T>, Collection<T>, List<T>
    Direct Known Subclasses:
    PaginatedParallelScanList, PaginatedQueryList, PaginatedScanList
    public abstract class PaginatedList<T>
extends Object
implements List<T>
    Unmodifiable list supporting paginated result sets from Amazon DynamoDB.

    Pages of results are fetched lazily from DynamoDB as they are needed. Some methods, such as size() and toArray(), require fetching the entire result set eagerly. See the javadoc of individual methods for details on which are lazy.

    • Field Detail

      • mapper

        protected final DynamoDBMapper mapper
        Reference to the DynamoDB mapper for marshalling DynamoDB attributes back into objects

      • clazz

        protected final Class<T> clazz
        The class annotated with DynamoDB tags declaring how to load/store objects into DynamoDB

      • dynamo

        protected final AmazonDynamoDB dynamo
        The client for working with DynamoDB

      • allResultsLoaded

        protected boolean allResultsLoaded
        Tracks if all results have been loaded yet or not

      • allResults

        protected final List<T> allResults
        All currently loaded results for this list. In ITERATION_ONLY mode, this list will at most keep one page of the loaded results, and all previous results will be cleared from the memory.

      • nextResults

        protected final List<T> nextResults
        Lazily loaded next results waiting to be added into allResults

    • Constructor Detail

      • PaginatedList

        public PaginatedList​(DynamoDBMapper mapper,
                     Class<T> clazz,
                     AmazonDynamoDB dynamo)
        Constructs a PaginatedList instance using the default PaginationLoadingStrategy

      • PaginatedList

        public PaginatedList​(DynamoDBMapper mapper,
                     Class<T> clazz,
                     AmazonDynamoDB dynamo,
                     DynamoDBMapperConfig.PaginationLoadingStrategy paginationLoadingStrategy)
        Constructs a PaginatedList instance.
        Parameters:
        mapper - The mapper for marshalling DynamoDB attributes into objects.
        clazz - The class of the annotated model.
        dynamo - The DynamoDB client for making low-level request calls.
        paginationLoadingStrategy - The strategy used for loading paginated results. Caller has to explicitly set this parameter, since the DynamoDBMapperConfig set in the mapper is not accessible here. If null value is provided, LAZY_LOADING will be set by default.

    • Method Detail

      • loadAllResults

        public void loadAllResults()
        Eagerly loads all results for this list.

        Not supported in ITERATION_ONLY mode.

      • fetchNextPage

        protected abstract List<T> fetchNextPage()
        Fetches the next page of results (which may be empty) and returns any items found.

      • atEndOfResults

        protected abstract boolean atEndOfResults()
        Returns whether we have reached the end of the result set.

      • iterator

        public Iterator<T> iterator()
        Returns an iterator over this list that lazily initializes results as necessary.

        If it configured with ITERARTION_ONLY mode, then the iterator could be only retrieved once, and any previously loaded results will be cleared in the memory during the iteration.

        Specified by:
        iterator in interface Collection<T>
        Specified by:
        iterator in interface Iterable<T>
        Specified by:
        iterator in interface List<T>

      • isEmpty

        public boolean isEmpty()
        Returns whether the collection is empty. At most one (non-empty) page of results is loaded to make the check.

        Not supported in ITERATION_ONLY mode.

        Specified by:
        isEmpty in interface Collection<T>
        Specified by:
        isEmpty in interface List<T>

      • get

        public T get​(int n)
        Returns the Nth element of the list. Results are loaded until N elements are present, if necessary.

        Not supported in ITERATION_ONLY mode.

        Specified by:
        get in interface List<T>

      • contains

        public boolean contains​(Object arg0)
        Returns whether the collection contains the given element. Results are loaded and checked incrementally until a match is found or the end of the result set is reached.

        Not supported in ITERATION_ONLY mode.

        Specified by:
        contains in interface Collection<T>
        Specified by:
        contains in interface List<T>

      • subList

        public List<T> subList​(int arg0,
                       int arg1)
        Returns a sub-list in the range specified, loading more results as necessary.

        Not supported in ITERATION_ONLY mode.

        Specified by:
        subList in interface List<T>

      • indexOf

        public int indexOf​(Object arg0)
        Returns the first index of the object given in the list. Additional results are loaded incrementally as necessary.

        Not supported in ITERATION_ONLY mode.

        Specified by:
        indexOf in interface List<T>

      • remove

        public T remove​(int arg0)
        Specified by:
        remove in interface List<T>

      • set

        public T set​(int arg0,
             T arg1)
        Specified by:
        set in interface List<T>

      • add

        public boolean add​(T arg0)
        Specified by:
        add in interface Collection<T>
        Specified by:
        add in interface List<T>

      • add

        public void add​(int arg0,
                T arg1)
        Specified by:
        add in interface List<T>

      • addAll

        public boolean addAll​(int arg0,
                      Collection<? extends T> arg1)
        Specified by:
        addAll in interface List<T>