java.util.Optional.get()方法的使用及代码示例

x33g5p2x  于2022-01-17 转载在 其他  
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本文整理了Java中java.util.Optional.get()方法的一些代码示例，展示了Optional.get()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.get()方法的具体详情如下：
包路径：java.util.Optional
类名称：Optional
方法名：get

Optional.get介绍

[英]If a value is present in this Optional, returns the value, otherwise throws NoSuchElementException.
[中]如果此选项中存在一个值，则返回该值，否则抛出NoTouchElementException。

代码示例

代码示例来源：origin: stackoverflow.com

void foo(String a, Optional<Integer> bOpt) {
  Integer b = bOpt.isPresent() ? bOpt.get() : 0;
  //...
}

foo("a", Optional.of(2));
foo("a", Optional.<Integer>absent());

代码示例来源：origin: prestodb/presto

private static Optional<List<Symbol>> translateSymbols(Iterable<Symbol> partitioning, Function<Symbol, Optional<Symbol>> translator)
{
  ImmutableList.Builder<Symbol> newPartitioningColumns = ImmutableList.builder();
  for (Symbol partitioningColumn : partitioning) {
    Optional<Symbol> translated = translator.apply(partitioningColumn);
    if (!translated.isPresent()) {
      return Optional.empty();
    }
    newPartitioningColumns.add(translated.get());
  }
  return Optional.of(newPartitioningColumns.build());
}

代码示例来源：origin: prestodb/presto

public long getTotalPartitionsCount(String keyspace, String table, Optional<Long> sessionSplitsPerNode)
{
  if (sessionSplitsPerNode.isPresent()) {
    return sessionSplitsPerNode.get();
  }
  else if (configSplitsPerNode.isPresent()) {
    return configSplitsPerNode.get();
  }
  List<SizeEstimate> estimates = session.getSizeEstimates(keyspace, table);
  return estimates.stream()
      .mapToLong(SizeEstimate::getPartitionsCount)
      .sum();
}

代码示例来源：origin: spring-projects/spring-framework

@Test
public void getMediaType() {
  assertEquals(MediaType.APPLICATION_XML, MediaTypeFactory.getMediaType("file.xml").get());
  assertEquals(MediaType.parseMediaType("application/javascript"), MediaTypeFactory.getMediaType("file.js").get());
  assertEquals(MediaType.parseMediaType("text/css"), MediaTypeFactory.getMediaType("file.css").get());
  assertFalse(MediaTypeFactory.getMediaType("file.foobar").isPresent());
}

代码示例来源：origin: spring-projects/spring-framework

@Test
@SuppressWarnings("unchecked")
public void createAttributeUriTemplateVarWithOptional() throws Exception {
  Map<String, String> uriTemplateVars = new HashMap<>();
  uriTemplateVars.put("testBean3", "Patty");
  request.setAttribute(HandlerMapping.URI_TEMPLATE_VARIABLES_ATTRIBUTE, uriTemplateVars);
  // Type conversion from "Patty" to TestBean via TestBean(String) constructor
  Optional<TestBean> testBean = (Optional<TestBean>) processor.resolveArgument(
      testBeanWithOptionalModelAttr, mavContainer, webRequest, binderFactory);
  assertEquals("Patty", testBean.get().getName());
}

代码示例来源：origin: spring-projects/spring-framework

@Test
@SuppressWarnings("rawtypes")
public void resolveOptionalParamList() throws Exception {
  ConfigurableWebBindingInitializer initializer = new ConfigurableWebBindingInitializer();
  initializer.setConversionService(new DefaultConversionService());
  WebDataBinderFactory binderFactory = new DefaultDataBinderFactory(initializer);
  MethodParameter param = this.testMethod.annotPresent(RequestParam.class).arg(Optional.class, List.class);
  Object result = resolver.resolveArgument(param, null, webRequest, binderFactory);
  assertEquals(Optional.empty(), result);
  request.addParameter("name", "123", "456");
  result = resolver.resolveArgument(param, null, webRequest, binderFactory);
  assertEquals(Optional.class, result.getClass());
  assertEquals(Arrays.asList("123", "456"), ((Optional) result).get());
}

代码示例来源：origin: prestodb/presto

private static Optional<Domain> getDomain(OptionalInt timestampOrdinalPosition, TupleDomain<LocalFileColumnHandle> predicate)
{
  Optional<Map<LocalFileColumnHandle, Domain>> domains = predicate.getDomains();
  Domain domain = null;
  if (domains.isPresent() && timestampOrdinalPosition.isPresent()) {
    Map<LocalFileColumnHandle, Domain> domainMap = domains.get();
    Set<Domain> timestampDomain = domainMap.entrySet().stream()
        .filter(entry -> entry.getKey().getOrdinalPosition() == timestampOrdinalPosition.getAsInt())
        .map(Map.Entry::getValue)
        .collect(toSet());
    if (!timestampDomain.isEmpty()) {
      domain = Iterables.getOnlyElement(timestampDomain);
    }
  }
  return Optional.ofNullable(domain);
}

代码示例来源：origin: spring-projects/spring-framework

@Test
public void resolveOptionalParamValue() {
  ServerWebExchange exchange = MockServerWebExchange.from(MockServerHttpRequest.get("/"));
  MethodParameter param = this.testMethod.arg(forClassWithGenerics(Optional.class, Integer.class));
  Object result = resolve(param, exchange);
  assertEquals(Optional.empty(), result);
  exchange = MockServerWebExchange.from(MockServerHttpRequest.get("/path?name=123"));
  result = resolve(param, exchange);
  assertEquals(Optional.class, result.getClass());
  Optional<?> value = (Optional<?>) result;
  assertTrue(value.isPresent());
  assertEquals(123, value.get());
}

代码示例来源：origin: prestodb/presto

public List<SchemaTableName> listTables(Optional<String> schemaName)
{
  return tableDescriptions.getAllSchemaTableNames()
      .stream()
      .filter(schemaTableName -> !schemaName.isPresent() || schemaTableName.getSchemaName().equals(schemaName.get()))
      .collect(toImmutableList());
}

代码示例来源：origin: apache/storm

private static int getMaxTaskId(Map<String, List<Integer>> componentToSortedTasks) {
  int maxTaskId = -1;
  for (List<Integer> integers : componentToSortedTasks.values()) {
    if (!integers.isEmpty()) {
      int tempMax = integers.stream().max(Integer::compareTo).get();
      if (tempMax > maxTaskId) {
        maxTaskId = tempMax;
      }
    }
  }
  return maxTaskId;
}

代码示例来源：origin: prestodb/presto

public Optional<WithQuery> getNamedQuery(String name)
{
  if (namedQueries.containsKey(name)) {
    return Optional.of(namedQueries.get(name));
  }
  if (parent.isPresent()) {
    return parent.get().getNamedQuery(name);
  }
  return Optional.empty();
}

代码示例来源：origin: prestodb/presto

@JsonCreator
// Available for Jackson deserialization only!
public static <T> TupleDomain<T> fromColumnDomains(@JsonProperty("columnDomains") Optional<List<ColumnDomain<T>>> columnDomains)
{
  if (!columnDomains.isPresent()) {
    return none();
  }
  return withColumnDomains(columnDomains.get().stream()
      .collect(toMap(ColumnDomain::getColumn, ColumnDomain::getDomain)));
}

代码示例来源：origin: spring-projects/spring-framework

@Test
public void testOptionalListMethodInjectionWithBeanAvailable() {
  bf.registerBeanDefinition("annotatedBean", new RootBeanDefinition(OptionalListMethodInjectionBean.class));
  bf.registerBeanDefinition("testBean", new RootBeanDefinition(TestBean.class));
  OptionalListMethodInjectionBean bean = (OptionalListMethodInjectionBean) bf.getBean("annotatedBean");
  assertTrue(bean.getTestBean().isPresent());
  assertSame(bf.getBean("testBean"), bean.getTestBean().get().get(0));
}

代码示例来源：origin: spring-projects/spring-framework

@Test
@SuppressWarnings("unchecked")
public void createAttributeRequestParameterWithOptional() throws Exception {
  request.addParameter("testBean3", "Patty");
  Optional<TestBean> testBean = (Optional<TestBean>) processor.resolveArgument(
      testBeanWithOptionalModelAttr, mavContainer, webRequest, binderFactory);
  assertEquals("Patty", testBean.get().getName());
}

代码示例来源：origin: spring-projects/spring-framework

@Test
@SuppressWarnings("rawtypes")
public void resolveOptionalParamValue() throws Exception {
  ConfigurableWebBindingInitializer initializer = new ConfigurableWebBindingInitializer();
  initializer.setConversionService(new DefaultConversionService());
  WebDataBinderFactory binderFactory = new DefaultDataBinderFactory(initializer);
  MethodParameter param = this.testMethod.annotPresent(RequestParam.class).arg(Optional.class, Integer.class);
  Object result = resolver.resolveArgument(param, null, webRequest, binderFactory);
  assertEquals(Optional.empty(), result);
  request.addParameter("name", "123");
  result = resolver.resolveArgument(param, null, webRequest, binderFactory);
  assertEquals(Optional.class, result.getClass());
  assertEquals(123, ((Optional) result).get());
}

代码示例来源：origin: google/guava

/**
 * If a value is present in {@code optional}, returns a stream containing only that element,
 * otherwise returns an empty stream.
 *
 * <p><b>Java 9 users:</b> use {@code optional.stream()} instead.
 */
public static <T> Stream<T> stream(java.util.Optional<T> optional) {
 return optional.isPresent() ? Stream.of(optional.get()) : Stream.of();
}

代码示例来源：origin: prestodb/presto

private Set<NullableValue> filterValues(Set<NullableValue> nullableValues, TpchColumn<?> column, Constraint<ColumnHandle> constraint)
{
  return nullableValues.stream()
      .filter(convertToPredicate(constraint.getSummary(), toColumnHandle(column)))
      .filter(value -> !constraint.predicate().isPresent() || constraint.predicate().get().test(ImmutableMap.of(toColumnHandle(column), value)))
      .collect(toSet());
}

代码示例来源：origin: prestodb/presto

private Optional<Symbol> canonicalize(Optional<Symbol> symbol)
{
  if (symbol.isPresent()) {
    return Optional.of(canonicalize(symbol.get()));
  }
  return Optional.empty();
}

代码示例来源：origin: prestodb/presto

public boolean hasAllOutputs(TableScanNode node)
{
  if (!layout.getColumns().isPresent()) {
    return true;
  }
  Set<ColumnHandle> columns = ImmutableSet.copyOf(layout.getColumns().get());
  List<ColumnHandle> nodeColumnHandles = node.getOutputSymbols().stream()
      .map(node.getAssignments()::get)
      .collect(toImmutableList());
  return columns.containsAll(nodeColumnHandles);
}

代码示例来源：origin: spring-projects/spring-framework

@Test
public void testOptionalListFieldInjectionWithBeanAvailable() {
  bf.registerBeanDefinition("annotatedBean", new RootBeanDefinition(OptionalListFieldInjectionBean.class));
  bf.registerBeanDefinition("testBean", new RootBeanDefinition(TestBean.class));
  OptionalListFieldInjectionBean bean = (OptionalListFieldInjectionBean) bf.getBean("annotatedBean");
  assertTrue(bean.getTestBean().isPresent());
  assertSame(bf.getBean("testBean"), bean.getTestBean().get().get(0));
}

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