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    1. /*
    2.  * Licensed to the Apache Software Foundation (ASF) under one
    3.  * or more contributor license agreements.  See the NOTICE file
    4.  * distributed with this work for additional information
    5.  * regarding copyright ownership.  The ASF licenses this file
    6.  * to you under the Apache License, Version 2.0 (the
    7.  * "License"); you may not use this file except in compliance
    8.  * with the License.  You may obtain a copy of the License at
    9.  *
    10.  *     http://www.apache.org/licenses/LICENSE-2.0
    11.  *
    12.  * Unless required by applicable law or agreed to in writing, software
    13.  * distributed under the License is distributed on an "AS IS" BASIS,
    14.  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    15.  * See the License for the specific language governing permissions and
    16.  * limitations under the License.
    17.  */
    19. package org.apache.flink.streaming.runtime.streamrecord;
    21. import org.apache.flink.annotation.Internal;
    22. import org.apache.flink.streaming.api.watermark.Watermark;
    23. import org.apache.flink.streaming.runtime.streamstatus.StreamStatus;
    25. /**
    26.  * An element in a data stream. Can be a record or a Watermark.
    27.  */
    28. @Internal
    29. public abstract class StreamElement {
    31.     /**
    32.      * Checks whether this element is a watermark.
    33.      * @return True, if this element is a watermark, false otherwise.
    34.      */
    35.     public final boolean isWatermark() {
    36.         return getClass() == Watermark.class;
    37.     }
    39.     /**
    40.      * Checks whether this element is a stream status.
    41.      * @return True, if this element is a stream status, false otherwise.
    42.      */
    43.     public final boolean isStreamStatus() {
    44.         return getClass() == StreamStatus.class;
    45.     }
    47.     /**
    48.      * Checks whether this element is a record.
    49.      * @return True, if this element is a record, false otherwise.
    50.      */
    51.     public final boolean isRecord() {
    52.         return getClass() == StreamRecord.class;
    53.     }
    55.     /**
    56.      * Checks whether this element is a latency marker.
    57.      * @return True, if this element is a latency marker, false otherwise.
    58.      */
    59.     public final boolean isLatencyMarker() {
    60.         return getClass() == LatencyMarker.class;
    61.     }
    63.     /**
    64.      * Casts this element into a StreamRecord.
    65.      * @return This element as a stream record.
    66.      * @throws java.lang.ClassCastException Thrown, if this element is actually not a stream record.
    67.      */
    68.     @SuppressWarnings("unchecked")
    69.     public final <E> StreamRecord<E> asRecord() {
    70.         return (StreamRecord<E>) this;
    71.     }
    73.     /**
    74.      * Casts this element into a Watermark.
    75.      * @return This element as a Watermark.
    76.      * @throws java.lang.ClassCastException Thrown, if this element is actually not a Watermark.
    77.      */
    78.     public final Watermark asWatermark() {
    79.         return (Watermark) this;
    80.     }
    82.     /**
    83.      * Casts this element into a StreamStatus.
    84.      * @return This element as a StreamStatus.
    85.      * @throws java.lang.ClassCastException Thrown, if this element is actually not a Stream Status.
    86.      */
    87.     public final StreamStatus asStreamStatus() {
    88.         return (StreamStatus) this;
    89.     }
    91.     /**
    92.      * Casts this element into a LatencyMarker.
    93.      * @return This element as a LatencyMarker.
    94.      * @throws java.lang.ClassCastException Thrown, if this element is actually not a LatencyMarker.
    95.      */
    96.     public final LatencyMarker asLatencyMarker() {
    97.         return (LatencyMarker) this;
    98.     }
    99. }