本文整理了Java中com.google.common.base.Optional.fromNullable()方法的一些代码示例，展示了Optional.fromNullable()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.fromNullable()方法的具体详情如下：
包路径：com.google.common.base.Optional
类名称：Optional
方法名：fromNullable

Optional.fromNullable介绍

[英]If nullableReference is non-null, returns an Optional instance containing that reference; otherwise returns Optional#absent.

Comparison to java.util.Optional: this method is equivalent to Java 8's Optional.ofNullable.
[中]如果nullableReference为非null，则返回包含该引用的可选实例；否则返回可选#缺席。
与java的比较。util。可选：此方法相当于Java8的可选方法。完全可以。

代码示例

代码示例来源：origin: apache/incubator-druid

public Optional<SupervisorSpec> getSupervisorSpec(String id)
{
 Pair<Supervisor, SupervisorSpec> supervisor = supervisors.get(id);
 return supervisor == null ? Optional.absent() : Optional.fromNullable(supervisor.rhs);
}

代码示例来源：origin: spotify/helios

private TaskStatus(final Builder builder) {
 this.job = checkNotNull(builder.job, "job");
 this.goal = checkNotNull(builder.goal, "goal");
 this.state = checkNotNull(builder.state, "state");
 // Optional
 this.containerId = builder.containerId;
 this.throttled = Optional.fromNullable(builder.throttled).or(ThrottleState.NO);
 this.ports = Optional.fromNullable(builder.ports).or(EMPTY_PORTS);
 this.env = Optional.fromNullable(builder.env).or(Maps.<String, String>newHashMap());
 this.containerError = Optional.fromNullable(builder.containerError).or("");
}

代码示例来源：origin: dreamhead/moco

@Override
  protected Optional<String> doExtract(final HttpRequest request) {
    Optional<ImmutableMap<String, String>> cookies = extractor.extract(request);
    if (cookies.isPresent()) {
      return fromNullable(cookies.get().get(this.key));
    }

    return Optional.absent();
  }
}

代码示例来源：origin: apache/incubator-gobblin

/**
 * Execute queries.
 *
 * @param queries the queries
 * @param proxy the proxy
 * @throws SQLException the sql exception
 */
public void executeQueries(List<String> queries, Optional<String> proxy)
  throws SQLException {
 Preconditions.checkArgument(!this.statementMap.isEmpty(), "No hive connection. Unable to execute queries");
 if (!proxy.isPresent()) {
  Preconditions.checkArgument(this.statementMap.size() == 1, "Multiple Hive connections. Please specify a user");
  proxy = Optional.fromNullable(this.statementMap.keySet().iterator().next());
 }
 Statement statement = this.statementMap.get(proxy.get());
 for (String query : queries) {
  statement.execute(query);
 }
}

代码示例来源：origin: google/guava

public void testFromNullable() {
 Optional<String> optionalName = Optional.fromNullable("bob");
 assertEquals("bob", optionalName.get());
}

代码示例来源：origin: apache/incubator-gobblin

@Override
public SharedResourceFactoryResponse<RestClient>
 createResource(SharedResourcesBroker<S> broker, ScopedConfigView<S, SharedRestClientKey> config) throws NotConfiguredException {
 try {
  SharedRestClientKey key = config.getKey();
  if (!(key instanceof UriRestClientKey)) {
   return new ResourceCoordinate<>(this, new UriRestClientKey(key.serviceName, resolveUriPrefix(config.getConfig(), key)),
     config.getScope());
  }
  String uriPrefix = ((UriRestClientKey) key).getUri();
  HttpClientFactory http = new HttpClientFactory(FilterChains.empty(),
    new NioEventLoopGroup(0 /* use default settings */,
      ExecutorsUtils.newDaemonThreadFactory(Optional.<Logger>absent(), Optional.of("R2 Nio Event Loop-%d"))),
    true,
    Executors.newSingleThreadScheduledExecutor(
      ExecutorsUtils.newDaemonThreadFactory(Optional.<Logger>absent(), Optional.of("R2 Netty Scheduler"))),
    true);
  Client r2Client = new TransportClientAdapter(http.getClient(Collections.<String, String>emptyMap()));
  return new ResourceInstance<>(new RestClient(r2Client,uriPrefix));
 } catch (URISyntaxException use) {
  throw new RuntimeException("Could not create a rest client for key " + Optional.fromNullable(config.getKey().toConfigurationKey()).or("null"));
 }
}

代码示例来源：origin: spotify/helios

this.hostname = Optional.fromNullable(hostname).orNull();
this.created = Optional.fromNullable(created).orNull();
this.command = Optional.fromNullable(command).or(EMPTY_COMMAND);
this.env = Optional.fromNullable(env).or(EMPTY_ENV);
this.resources = Optional.fromNullable(resources).orNull();
this.ports = Optional.fromNullable(ports).or(EMPTY_PORTS);
this.registration = Optional.fromNullable(registration).or(EMPTY_REGISTRATION);
this.gracePeriod = Optional.fromNullable(gracePeriod).orNull();
this.volumes = Optional.fromNullable(volumes).or(EMPTY_VOLUMES);
this.expires = expires;
this.registrationDomain = Optional.fromNullable(registrationDomain)
  .or(EMPTY_REGISTRATION_DOMAIN);
this.creatingUser = Optional.fromNullable(creatingUser).orNull();
this.token = Optional.fromNullable(token).or(EMPTY_TOKEN);
this.healthCheck = Optional.fromNullable(healthCheck).orNull();
this.securityOpt = Optional.fromNullable(securityOpt).or(EMPTY_SECURITY_OPT);
this.networkMode = Optional.fromNullable(networkMode).orNull();
this.metadata = Optional.fromNullable(metadata).or(EMPTY_METADATA);
this.addCapabilities = firstNonNull(addCapabilities, EMPTY_CAPS);
this.dropCapabilities = firstNonNull(dropCapabilities, EMPTY_CAPS);
this.labels = Optional.fromNullable(labels).or(EMPTY_LABELS);
this.secondsToWaitBeforeKill = secondsToWaitBeforeKill;
this.ramdisks = firstNonNull(ramdisks, EMPTY_RAMDISKS);
this.rolloutOptions = rolloutOptions;
this.runtime = Optional.fromNullable(runtime).orNull();

代码示例来源：origin: dreamhead/moco

@Override
  protected Optional<String> doExtract(final HttpRequest request) {
    Optional<ImmutableMap<String, String>> forms = extractor.extract(request);
    if (forms.isPresent()) {
      return fromNullable(forms.get().get(key));
    }

    return Optional.absent();
  }
}

代码示例来源：origin: apache/incubator-gobblin

public static String getProperty(HivePartitionDataset dataset, String property, long defaultValue) {
  Optional<String> propertyValueOptional = Optional.fromNullable(dataset.getParams().get(property));
  if (!propertyValueOptional.isPresent()) {
   return Long.toString(defaultValue);
  }
  try {
   long propertyVal = Long.parseLong(propertyValueOptional.get());
   if (propertyVal < 0) {
    return Long.toString(defaultValue);
   } else {
    return Long.toString(propertyVal);
   }
  } catch (NumberFormatException e) {
   return Long.toString(defaultValue);
  }
 }
}

代码示例来源：origin: google/j2objc

FluentIterable(Iterable<E> iterable) {
 checkNotNull(iterable);
 this.iterableDelegate = Optional.fromNullable(this != iterable ? iterable : null);
}

代码示例来源：origin: spotify/helios

private static String env(final String name, final String defaultValue) {
 return Optional.fromNullable(getenv(name)).or(defaultValue);
}

代码示例来源：origin: apache/usergrid

public static Optional<EntityMap> fromEntity(Optional<Entity> entity) {
  if(entity.isPresent()){
    EntityMap map =  fromEntity(entity.get());
    return Optional.fromNullable(map);
  }else{
    return Optional.absent();
  }
}

代码示例来源：origin: apache/incubator-druid

for (String dimension : dimensions) {
 Optional<RangeSet<String>> optFilterRangeSet = dimensionRangeCache
   .computeIfAbsent(dimension, d -> Optional.fromNullable(dimFilter.getDimensionRangeSet(d)));
 if (optFilterRangeSet.isPresent()) {
  filterDomain.put(dimension, optFilterRangeSet.get());

代码示例来源：origin: apache/incubator-gobblin

public Left(S s) {
 super(Optional.fromNullable(s), Optional.<T>absent());
}

代码示例来源：origin: spotify/docker-client

public String getHost() {
 return fromNullable(uri.getHost()).or("localhost");
}

代码示例来源：origin: apache/incubator-gobblin

InnerTimer(MetricContext context, String name, ContextAwareTimer contextAwareTimer) {
 this.name = name;
 Optional<MetricContext> parentContext = context.getParent();
 if (parentContext.isPresent()) {
  this.parentTimer = Optional.fromNullable(parentContext.get().contextAwareTimer(name));
 } else {
  this.parentTimer = Optional.absent();
 }
 this.timer = new WeakReference<>(contextAwareTimer);
}

代码示例来源：origin: immutables/immutables

@Override
@Value.Lazy
public Optional<String[]> depluralize() {
 @Nullable String[] dictionary = null;
 Optional<DeclaringPackage> parent = namedParentPackage();
 if (parent.isPresent()) {
  Optional<String[]> depluralize = parent.get().depluralize();
  if (depluralize.isPresent()) {
   dictionary = concat(dictionary, depluralize.get());
  }
 }
 Optional<String[]> depluralize = super.depluralize();
 if (depluralize.isPresent()) {
  dictionary = concat(dictionary, depluralize.get());
 }
 return Optional.fromNullable(dictionary);
}

代码示例来源：origin: apache/incubator-gobblin

public Right(T t) {
 super(Optional.<S>absent(), Optional.fromNullable(t));
}

代码示例来源：origin: BroadleafCommerce/BroadleafCommerce

protected String getLastFragment(String url) {
    URI uri = URI.create(url);
    String path = Optional.fromNullable(uri.getPath()).or("/");
    return path.substring(path.lastIndexOf('/') + 1);
  }
}

代码示例来源：origin: apache/incubator-gobblin

InnerMeter(MetricContext context, String name, ContextAwareMeter contextAwareMeter) {
 this.name = name;
 Optional<MetricContext> parentContext = context.getParent();
 if (parentContext.isPresent()) {
  this.parentMeter = Optional.fromNullable(parentContext.get().contextAwareMeter(name));
 } else {
  this.parentMeter = Optional.absent();
 }
 this.contextAwareMeter = new WeakReference<>(contextAwareMeter);
}