本文整理了Java中org.apache.spark.api.java.Optional类的一些代码示例，展示了Optional类的具体用法。这些代码示例主要来源于Github/Stackoverflow/Maven等平台，是从一些精选项目中提取出来的代码，具有较强的参考意义，能在一定程度帮忙到你。Optional类的具体详情如下：
包路径：org.apache.spark.api.java.Optional
类名称：Optional

Optional介绍

[英]Like java.util.Optional in Java 8, scala.Option in Scala, and com.google.common.base.Optional in Google Guava, this class represents a value of a given type that may or may not exist. It is used in methods that wish to optionally return a value, in preference to returning null.

In fact, the class here is a reimplementation of the essential API of both java.util.Optional and com.google.common.base.Optional. From java.util.Optional, it implements:

• #empty()
• #of(Object)
• #ofNullable(Object)
• #get()
• #orElse(Object)
• #isPresent()

From com.google.common.base.Optional it implements:

• #absent()
• #of(Object)
• #fromNullable(Object)
• #get()
• #or(Object)
• #orNull()
• #isPresent()

java.util.Optional itself was not used because at the time, the project did not require Java 8. Using com.google.common.base.Optionalhas in the past caused serious library version conflicts with Guava that can't be resolved by shading. Hence this work-alike clone.
[中]比如java。util。在Java8中，scala是可选的。Scala和com中的选项。谷歌。常见的基础在Google Guava中是可选的，该类表示给定类型的值，该值可能存在，也可能不存在。它用于希望选择性地返回值的方法中，而不是返回null。
实际上，这里的类是java和java的基本API的重新实现。util。可选和com。谷歌。常见的基础可选择的来自java。util。可选，它实现：
*#空的（）
*#of（物体）
*#of nullable（对象）
*#得到（）
*#orElse（对象）
*#isPresent（）
来自com。谷歌。常见的基础可选，它实现：
*#缺席（）
*#of（物体）
*#fromNullable（对象）
*#得到（）
*#或（对象）
*#orNull（）
*#isPresent（）
JAVAutil。Optional本身没有被使用，因为当时该项目不需要Java8。使用com。谷歌。常见的基础Optionalhas过去曾与番石榴造成严重的库版本冲突，无法通过着色解决。因此，这项工作类似于克隆。

代码示例

代码示例来源：origin: org.apache.spark/spark-core_2.10

@Test
public void testOf() {
 Assert.assertTrue(Optional.of(1).isPresent());
 Assert.assertNotNull(Optional.of(1).orNull());
 Assert.assertEquals(Integer.valueOf(1), Optional.of(1).get());
 Assert.assertEquals(Integer.valueOf(1), Optional.of(1).or(2));
 Assert.assertEquals(Integer.valueOf(1), Optional.of(1).orElse(2));
}

代码示例来源：origin: org.apache.spark/spark-core

@Test
public void testEmpty() {
 Assert.assertFalse(Optional.empty().isPresent());
 Assert.assertNull(Optional.empty().orNull());
 Assert.assertEquals("foo", Optional.empty().or("foo"));
 Assert.assertEquals("foo", Optional.empty().orElse("foo"));
}

代码示例来源：origin: org.apache.spark/spark-core_2.10

@Test
public void testOfNullable() {
 Assert.assertTrue(Optional.ofNullable(1).isPresent());
 Assert.assertNotNull(Optional.ofNullable(1).orNull());
 Assert.assertEquals(Integer.valueOf(1), Optional.ofNullable(1).get());
 Assert.assertEquals(Integer.valueOf(1), Optional.ofNullable(1).or(2));
 Assert.assertEquals(Integer.valueOf(1), Optional.ofNullable(1).orElse(2));
 Assert.assertFalse(Optional.ofNullable(null).isPresent());
 Assert.assertNull(Optional.ofNullable(null).orNull());
 Assert.assertEquals(Integer.valueOf(2), Optional.<Integer>ofNullable(null).or(2));
 Assert.assertEquals(Integer.valueOf(2), Optional.<Integer>ofNullable(null).orElse(2));
}

代码示例来源：origin: org.apache.spark/spark-core

/**
 * @param value value to wrap, which may be null
 * @return {@code Optional} wrapping this value, which may be empty
 */
public static <T> Optional<T> ofNullable(T value) {
 if (value == null) {
  return empty();
 } else {
  return of(value);
 }
}

代码示例来源：origin: org.apache.spark/spark-core_2.10

@Test(expected = NullPointerException.class)
public void testAbsentGet() {
 Optional.absent().get();
}

代码示例来源：origin: apache/tinkerpop

final JavaSparkContext sparkContext = new JavaSparkContext(Spark.create(hadoopConfiguration));
final Storage sparkContextStorage = SparkContextStorage.open();
  if (loadedGraphRDD.partitioner().isPresent())
    this.logger.debug("Using the existing partitioner associated with the loaded graphRDD: " + loadedGraphRDD.partitioner().get());
  else {
    if (!skipPartitioner) {
      final Partitioner partitioner = new HashPartitioner(this.workersSet ? this.workers : loadedGraphRDD.partitions().size());
      this.logger.debug("Partitioning the loaded graphRDD: " + partitioner);
      loadedGraphRDD = loadedGraphRDD.partitionBy(partitioner);
      partitioned = true;
      assert loadedGraphRDD.partitioner().isPresent();
    } else {
      assert skipPartitioner == !loadedGraphRDD.partitioner().isPresent(); // no easy way to test this with a test case
      this.logger.debug("Partitioning has been skipped for the loaded graphRDD via " + GREMLIN_SPARK_SKIP_PARTITIONER);
          sparkContext.cancelAllJobs();
          throw new TraversalInterruptedException();

代码示例来源：origin: apache/tinkerpop

final Configuration vertexProgramConfiguration) { // has the VertexProgram.loadState() information
boolean partitionedGraphRDD = graphRDD.partitioner().isPresent();
  assert graphRDD.partitioner().get().equals(viewIncomingRDD.partitioner().get());
final JavaPairRDD<Object, ViewOutgoingPayload<M>> viewOutgoingRDD = ((null == viewIncomingRDD) ?
    graphRDD.mapValues(vertexWritable -> new Tuple2<>(vertexWritable, Optional.<ViewIncomingPayload<M>>absent())) : // first iteration will not have any views or messages
    graphRDD.leftOuterJoin(viewIncomingRDD))                                                   // every other iteration may have views and messages
        final boolean hasViewAndMessages = vertexViewIncoming._2()._2().isPresent(); // if this is the first iteration, then there are no views or messages
        final List<DetachedVertexProperty<Object>> previousView = hasViewAndMessages ? vertexViewIncoming._2()._2().get().getView() : memory.isInitialIteration() ? new ArrayList<>() : Collections.emptyList();
        final List<M> incomingMessages = hasViewAndMessages ? vertexViewIncoming._2()._2().get().getIncomingMessages() : Collections.emptyList();
  assert graphRDD.partitioner().get().equals(viewOutgoingRDD.partitioner().get());
        viewOutgoingRDD.flatMapToPair(messageFunction).reduceByKey(graphRDD.partitioner().get(), reducerFunction) :
        viewOutgoingRDD.flatMapToPair(messageFunction).reduceByKey(reducerFunction))
        .mapValues(payload -> { // handle various corner cases of when views don't exist, messages don't exist, or neither exists.
  assert graphRDD.partitioner().get().equals(newViewIncomingRDD.partitioner().get());
newViewIncomingRDD
    .foreachPartition(partitionIterator -> {

代码示例来源：origin: org.apache.spark/spark-core_2.11

@Test
public void leftOuterJoin() {
 JavaPairRDD<Integer, Integer> rdd1 = sc.parallelizePairs(Arrays.asList(
  new Tuple2<>(1, 1),
  new Tuple2<>(1, 2),
  new Tuple2<>(2, 1),
  new Tuple2<>(3, 1)
 ));
 JavaPairRDD<Integer, Character> rdd2 = sc.parallelizePairs(Arrays.asList(
  new Tuple2<>(1, 'x'),
  new Tuple2<>(2, 'y'),
  new Tuple2<>(2, 'z'),
  new Tuple2<>(4, 'w')
 ));
 List<Tuple2<Integer, Tuple2<Integer, Optional<Character>>>> joined =
  rdd1.leftOuterJoin(rdd2).collect();
 Assert.assertEquals(5, joined.size());
 Tuple2<Integer, Tuple2<Integer, Optional<Character>>> firstUnmatched =
  rdd1.leftOuterJoin(rdd2).filter(tup -> !tup._2()._2().isPresent()).first();
 Assert.assertEquals(3, firstUnmatched._1().intValue());
}

代码示例来源：origin: org.apache.spark/spark-core

@Test
public void checkpointAndRestore() {
 JavaRDD<Integer> rdd = sc.parallelize(Arrays.asList(1, 2, 3, 4, 5));
 sc.setCheckpointDir(tempDir.getAbsolutePath());
 assertFalse(rdd.isCheckpointed());
 rdd.checkpoint();
 rdd.count(); // Forces the DAG to cause a checkpoint
 assertTrue(rdd.isCheckpointed());
 assertTrue(rdd.getCheckpointFile().isPresent());
 JavaRDD<Integer> recovered = sc.checkpointFile(rdd.getCheckpointFile().get());
 assertEquals(Arrays.asList(1, 2, 3, 4, 5), recovered.collect());
}

代码示例来源：origin: org.apache.spark/spark-streaming_2.11

new Tuple2<>("new york", 2));
JavaRDD<Tuple2<String, Integer>> tmpRDD = ssc.sparkContext().parallelize(initial);
JavaPairRDD<String, Integer> initialRDD = JavaPairRDD.fromJavaRDD(tmpRDD);
  if (state.isPresent()) {
   out += state.get();
  return Optional.of(out);
 }, new HashPartitioner(1), initialRDD);
JavaTestUtils.attachTestOutputStream(updated);

代码示例来源：origin: seznam/euphoria

.setName(operator.getName() + "::extract-left")
.flatMapToPair(
  t -> {
      new Tuple2<>(
        t._1,
        new Tuple2<>(opt(t._2), Optional.<SparkElement>empty())))
      .iterator();
key ->
  context.getExecutionEnvironment()
    .broadcast(
      toBroadcast(
        left
      new Tuple2<>(
        t._1,
        new Tuple2<>(Optional.<SparkElement>empty(), opt(t._2))))
      .iterator();
 final SparkElement first = t._2._1.orNull();
 final SparkElement second = t._2._2.orNull();
 final Window window = first == null ? second.getWindow() : first.getWindow();
 final long maxTimestamp =

代码示例来源：origin: org.apache.spark/spark-core_2.11

pairs.add(new Tuple2<>(1, 3));
JavaPairRDD<Integer, Integer> rdd = sc.parallelizePairs(pairs);
  rdd.repartitionAndSortWithinPartitions(partitioner);
assertTrue(repartitioned.partitioner().isPresent());
assertEquals(repartitioned.partitioner().get(), partitioner);
List<List<Tuple2<Integer, Integer>>> partitions = repartitioned.glom().collect();
assertEquals(partitions.get(0),

代码示例来源：origin: apache/tinkerpop

public static <M> JavaPairRDD<Object, VertexWritable> prepareFinalGraphRDD(
    final JavaPairRDD<Object, VertexWritable> graphRDD,
    final JavaPairRDD<Object, ViewIncomingPayload<M>> viewIncomingRDD,
    final Set<VertexComputeKey> vertexComputeKeys) {
  // the graphRDD and the viewRDD must have the same partitioner
  if (graphRDD.partitioner().isPresent())
    assert (graphRDD.partitioner().get().equals(viewIncomingRDD.partitioner().get()));
  final String[] vertexComputeKeysArray = VertexProgramHelper.vertexComputeKeysAsArray(vertexComputeKeys); // the compute keys as an array
  return graphRDD.leftOuterJoin(viewIncomingRDD)
      .mapValues(tuple -> {
        final StarGraph.StarVertex vertex = tuple._1().get();
        vertex.dropVertexProperties(vertexComputeKeysArray); // drop all existing compute keys
        // attach the final computed view to the cached graph
        final List<DetachedVertexProperty<Object>> view = tuple._2().isPresent() ? tuple._2().get().getView() : Collections.emptyList();
        for (final DetachedVertexProperty<Object> property : view) {
          if (!VertexProgramHelper.isTransientVertexComputeKey(property.key(), vertexComputeKeys))
            property.attach(Attachable.Method.create(vertex));
        }
        return tuple._1();
      });
}

代码示例来源：origin: uber/hudi

public JavaPairRDD<HoodieKey, Optional<String>> fetchRecordLocation(JavaRDD<HoodieKey> hoodieKeys,
  JavaSparkContext jsc, HoodieTable<T> hoodieTable) {
 JavaPairRDD<String, String> partitionRecordKeyPairRDD = hoodieKeys
   .mapToPair(key -> new Tuple2<>(key.getPartitionPath(), key.getRecordKey()));
 // Lookup indexes for all the partition/recordkey pair
 JavaPairRDD<String, String> rowKeyFilenamePairRDD = lookupIndex(partitionRecordKeyPairRDD, jsc, hoodieTable);
 JavaPairRDD<String, HoodieKey> rowKeyHoodieKeyPairRDD = hoodieKeys
   .mapToPair(key -> new Tuple2<>(key.getRecordKey(), key));
 return rowKeyHoodieKeyPairRDD.leftOuterJoin(rowKeyFilenamePairRDD).mapToPair(keyPathTuple -> {
  Optional<String> recordLocationPath;
  if (keyPathTuple._2._2.isPresent()) {
   String fileName = keyPathTuple._2._2.get();
   String partitionPath = keyPathTuple._2._1.getPartitionPath();
   recordLocationPath = Optional
     .of(new Path(new Path(hoodieTable.getMetaClient().getBasePath(), partitionPath), fileName)
       .toUri().getPath());
  } else {
   recordLocationPath = Optional.absent();
  }
  return new Tuple2<>(keyPathTuple._2._1, recordLocationPath);
 });
}

代码示例来源：origin: uber/hudi

/**
 * Tag the <rowKey, filename> back to the original HoodieRecord RDD.
 */
private JavaRDD<HoodieRecord<T>> tagLocationBacktoRecords(
  JavaPairRDD<String, String> rowKeyFilenamePairRDD, JavaRDD<HoodieRecord<T>> recordRDD) {
 JavaPairRDD<String, HoodieRecord<T>> rowKeyRecordPairRDD = recordRDD
   .mapToPair(record -> new Tuple2<>(record.getRecordKey(), record));
 // Here as the recordRDD might have more data than rowKeyRDD (some rowKeys' fileId is null),
 // so we do left outer join.
 return rowKeyRecordPairRDD.leftOuterJoin(rowKeyFilenamePairRDD).values().map(v1 -> {
  HoodieRecord<T> record = v1._1();
  if (v1._2().isPresent()) {
   String filename = v1._2().get();
   if (filename != null && !filename.isEmpty()) {
    // When you have a record in multiple files in the same partition, then rowKeyRecordPairRDD will have 2
    // entries with the same exact in memory copy of the HoodieRecord and the 2 separate filenames that the
    // record is found in. This will result in setting currentLocation 2 times and it will fail the second time.
    // This check will create a new in memory copy of the hoodie record.
    if (record.getCurrentLocation() != null) {
     record = new HoodieRecord<T>(record.getKey(), record.getData());
    }
    record.setCurrentLocation(new HoodieRecordLocation(FSUtils.getCommitTime(filename),
      FSUtils.getFileId(filename)));
   }
  }
  return record;
 });
}

代码示例来源：origin: uber/marmaray

public long getCount() {
    if (!count.isPresent()) {
      this.count = Optional.of(this.data.count());
    }
    return count.get();
  }
}

代码示例来源：origin: com.davidbracewell/mango

@Override
public <V> MPairStream<T, Map.Entry<U, V>> leftOuterJoin(@NonNull MPairStream<? extends T, ? extends V> stream) {
 return new SparkPairStream<>(rdd.leftOuterJoin(toPairRDD(stream))
                 .mapToPair(t -> Cast.as(
                   new scala.Tuple2<>(t._1(), Tuple2.of(t._2()._1(), t._2()._2().or(null))))));
}

代码示例来源：origin: org.apache.spark/spark-core

@Test
public void testFromNullable() {
 Assert.assertTrue(Optional.fromNullable(1).isPresent());
 Assert.assertNotNull(Optional.fromNullable(1).orNull());
 Assert.assertEquals(Integer.valueOf(1), Optional.fromNullable(1).get());
 Assert.assertEquals(Integer.valueOf(1), Optional.fromNullable(1).or(2));
 Assert.assertEquals(Integer.valueOf(1), Optional.fromNullable(1).orElse(2));
 Assert.assertFalse(Optional.fromNullable(null).isPresent());
 Assert.assertNull(Optional.fromNullable(null).orNull());
 Assert.assertEquals(Integer.valueOf(2), Optional.<Integer>fromNullable(null).or(2));
 Assert.assertEquals(Integer.valueOf(2), Optional.<Integer>fromNullable(null).orElse(2));
}

代码示例来源：origin: com.davidbracewell/mango

@Override
public <V> MPairStream<T, Map.Entry<U, V>> rightOuterJoin(@NonNull MPairStream<? extends T, ? extends V> stream) {
 return new SparkPairStream<>(rdd.rightOuterJoin(toPairRDD(stream))
                 .mapToPair(t -> Cast.as(
                   new scala.Tuple2<>(t._1(), Tuple2.of(t._2()._1().or(null), t._2()._2())))));
}

代码示例来源：origin: org.apache.spark/spark-core_2.10

@Test
public void testAbsent() {
 Assert.assertFalse(Optional.absent().isPresent());
 Assert.assertNull(Optional.absent().orNull());
 Assert.assertEquals("foo", Optional.absent().or("foo"));
 Assert.assertEquals("foo", Optional.absent().orElse("foo"));
}