software.amazon.awssdk.services.databasemigration.paginators.DescribeEventsPaginator Maven / Gradle / Ivy

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The AWS Java SDK for AWS Database Migration Service module holds the client classes that are used for communicating with AWS Database Migration Service.
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/*
 * Copyright 2012-2017 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"). You may not use this file except in compliance with
 * the License. A copy of the License is located at
 * 
 * http://aws.amazon.com/apache2.0
 * 
 * or in the "license" file accompanying this file. This file is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
 * CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions
 * and limitations under the License.
 */

package software.amazon.awssdk.services.databasemigration.paginators;

import java.util.Iterator;
import javax.annotation.Generated;
import software.amazon.awssdk.core.pagination.NextPageFetcher;
import software.amazon.awssdk.core.pagination.PaginatedResponsesIterator;
import software.amazon.awssdk.core.pagination.SdkIterable;
import software.amazon.awssdk.services.databasemigration.DatabaseMigrationClient;
import software.amazon.awssdk.services.databasemigration.model.DescribeEventsRequest;
import software.amazon.awssdk.services.databasemigration.model.DescribeEventsResponse;

/**
 * 
 * Represents the output for the
 * {@link software.amazon.awssdk.services.databasemigration.DatabaseMigrationClient#describeEventsIterable(software.amazon.awssdk.services.databasemigration.model.DescribeEventsRequest)}
 * operation which is a paginated operation. This class is an iterable of
 * {@link software.amazon.awssdk.services.databasemigration.model.DescribeEventsResponse} that can be used to iterate
 * through all the response pages of the operation.
 * 
 * 
 * When the operation is called, an instance of this class is returned. At this point, no service calls are made yet and
 * so there is no guarantee that the request is valid. As you iterate through the iterable, SDK will start lazily
 * loading response pages by making service calls until there are no pages left or your iteration stops. If there are
 * errors in your request, you will see the failures only after you start iterating through the iterable.
 * 
 *
 * 
 * The following are few ways to iterate through the response pages:
 * 
 * 1) Using a Stream
 * 
 *  * {@code
 * software.amazon.awssdk.services.databasemigration.paginators.DescribeEventsPaginator responses = client.describeEventsIterable(request);
 * responses.stream().forEach(....);
 * }
 * 
 *
 * 2) Using For loop
 * 
 *  * {
 *     @code
 *     software.amazon.awssdk.services.databasemigration.paginators.DescribeEventsPaginator responses = client
 *             .describeEventsIterable(request);
 *     for (software.amazon.awssdk.services.databasemigration.model.DescribeEventsResponse response : responses) {
 *         // do something;
 *     }
 * }
 * 
 *
 * 3) Use iterator directly
 * 
 *  * {@code
 * software.amazon.awssdk.services.databasemigration.paginators.DescribeEventsPaginator responses = client.describeEventsIterable(request);
 * responses.iterator().forEachRemaining(....);
 * }
 * 
 * 
 * Note: If you prefer to have control on service calls, use the
 * {@link #describeEvents(software.amazon.awssdk.services.databasemigration.model.DescribeEventsRequest)} operation.
 * 
 */
@Generated("software.amazon.awssdk:codegen")
public final class DescribeEventsPaginator implements SdkIterable {
    private final DatabaseMigrationClient client;

    private final DescribeEventsRequest firstRequest;

    private final NextPageFetcher nextPageFetcher;

    public DescribeEventsPaginator(final DatabaseMigrationClient client, final DescribeEventsRequest firstRequest) {
        this.client = client;
        this.firstRequest = firstRequest;
        this.nextPageFetcher = new DescribeEventsResponseFetcher();
    }

    @Override
    public Iterator iterator() {
        return new PaginatedResponsesIterator(nextPageFetcher);
    }

    private class DescribeEventsResponseFetcher implements NextPageFetcher {
        @Override
        public boolean hasNextPage(DescribeEventsResponse previousPage) {
            return previousPage.marker() != null;
        }

        @Override
        public DescribeEventsResponse nextPage(DescribeEventsResponse previousPage) {
            if (previousPage == null) {
                return client.describeEvents(firstRequest);
            }
            return client.describeEvents(firstRequest.toBuilder().marker(previousPage.marker()).build());
        }
    }
}