Java Stream類代碼示例

import java.util.stream.Stream; //導入依賴的package包/類
void initJar() throws IOException {
    String testClassPath = System.getProperty("test.class.path", "");
    Path jarsrc = Stream.of(testClassPath.split(File.pathSeparator))
            .map(Paths::get)
            .filter(e -> e.endsWith("jarsrc"))
            .findAny()
            .orElseThrow(() -> new InternalError("jarsrc not found"));
    jarPath = Paths.get("lib.jar");
    try (JarOutputStream out = new JarOutputStream(Files.newOutputStream(jarPath))) {
        String[] classNames = {"Lib1.class", "Lib2.class"};
        for (String cn : classNames) {
            out.putNextEntry(new JarEntry("lib/" + cn));
            Path libClass = jarsrc.resolve("lib").resolve(cn);
            out.write(Files.readAllBytes(libClass));
        }
    }
}
 

import java.util.stream.Stream; //導入依賴的package包/類
private Stream<File> searchDir(File dir, boolean warnOnBadDir) {
  if (dir == null || !dir.exists() || !dir.isDirectory()) {
    if (warnOnBadDir && dir != null) {
      getLog().warn("Directory does not exist or is not a directory: " + dir);
    }
    return Stream.empty();
  }
  getLog().debug("Adding directory " + dir);
  DirectoryScanner ds = new DirectoryScanner();
  ds.setBasedir(dir);
  ds.setIncludes(includes != null && includes.length > 0 ? includes : DEFAULT_INCLUDES);
  ds.setExcludes(excludes);
  ds.addDefaultExcludes();
  ds.setCaseSensitive(false);
  ds.setFollowSymlinks(false);
  ds.scan();
  return Stream.of(ds.getIncludedFiles()).map(filename -> new File(dir, filename)).parallel();
}
 

import java.util.stream.Stream; //導入依賴的package包/類
@Test
public void testMapPartialNull() throws Exception {
    repeat(3, i -> {
        Map<Object, Object> m1 = Stream.of("a" + i, "b" + i, "c" + i).collect(toMap(o -> o, o -> o + "test"));

        when(rpc1.map(or(eq(singletonMap(i + 1, i)), eq(singletonMap(i + 2, i))))).thenReturn(m1);
        when(rpc2.map(or(eq(singletonMap(i + 1, i)), eq(singletonMap(i + 2, i))))).thenReturn(null);

        Map<Object, Object> args = new HashMap<>();
        args.put(i + 1, i);
        args.put(i + 2, i);

        Map<Object, Object> result = client.map(args);

        assertEquals(m1, result);

        verify(rpc1).map(or(eq(singletonMap(i + 1, i)), eq(singletonMap(i + 2, i))));
        verify(rpc2).map(or(eq(singletonMap(i + 1, i)), eq(singletonMap(i + 2, i))));

        verifyNoMoreInteractions(rpc1, rpc2);
        reset(rpc1, rpc2);
    });
}
 

import java.util.stream.Stream; //導入依賴的package包/類
@Override
public void execute(Tuple tuple) {
    final String data = tuple.getString(0);
    LOGGER.debug("Processing datapoint", data);
    try {
        Datapoint datapoint = MAPPER.readValue(data, Datapoint.class);
        if (isUpdateRequired(datapoint)) {
            addDatapoint(datapoint);

            List<Object> stream = Stream.of(datapoint.getMetric(), datapoint.getTime(), datapoint.getValue(),
                    datapoint.getTags())
                    .collect(Collectors.toList());

            LOGGER.debug("emit: " + stream);
            collector.emit(stream);
        }
    } catch (IOException e) {
        LOGGER.error("Failed read datapoint", e);
    } finally {
        collector.ack(tuple);
    }
}
 

import java.util.stream.Stream; //導入依賴的package包/類
@Test(dataProvider = "styles")
public void testPlusScalar(DataFrameAlgebra.Lib lib, boolean parallel) {
    DataFrameAlgebra.LIBRARY.set(lib);
    Stream.of(int.class, long.class, double.class).forEach(type -> {
        Array.of(20, 77, 95, 135, 233, 245).forEach(count -> {
            final DataFrame<Integer,Integer> frame = random(120, count, parallel, type);
            final DataFrame<Integer,Integer> result = frame.plus(25);
            assertEquals(result, v -> {
                switch (ArrayType.of(type)) {
                    case INTEGER:   return frame.data().getInt(v.rowOrdinal(), v.colOrdinal()) + 25;
                    case LONG:      return frame.data().getLong(v.rowOrdinal(), v.colOrdinal()) + 25;
                    default:        return frame.data().getDouble(v.rowOrdinal(), v.colOrdinal()) + 25d;
                }
            });
        });
    });
}
 

import java.util.stream.Stream; //導入依賴的package包/類
@Override
public SharedInterProcessLock getLock(String application, EntityType entityType) {
    if (! connector.isConnected()) {
        throw new RedirectorDataSourceException("No connection to zookeeper");
    }

    String lockPath = Stream
        .of(REDIRECTOR_ZOOKEEPER_PATH, SERVICES_PATH, application, REDIRECTOR_LOCK_PATH, entityType.getPath())
        .collect(Collectors.joining(DELIMETER, DELIMETER, ""));

    if (lockMap.containsKey(lockPath)) {
        return lockMap.get(lockPath);
    } else {
        SharedInterProcessLock lock = connector.createLock(lockPath);
        lockMap.put(lockPath, lock);
        return lock;
    }
}
 

import java.util.stream.Stream; //導入依賴的package包/類
@Test
public void verifySaveAttributeReleasePolicyAllowedAttrRulesAndFilter() {
    final RegexRegisteredService r = new RegexRegisteredService();
    r.setName("testSaveAttributeReleasePolicyAllowedAttrRulesAndFilter");
    r.setServiceId(SERVICE_ID);
    r.setTheme("testtheme");
    r.setEvaluationOrder(1000);
    r.setAccessStrategy(new DefaultRegisteredServiceAccessStrategy(true, false));
    r.setProxyPolicy(new RegexMatchingRegisteredServiceProxyPolicy("https://.+"));
    r.setRequiredHandlers(Stream.of("h1", "h2").collect(Collectors.toSet()));

    final ReturnAllowedAttributeReleasePolicy policy = new ReturnAllowedAttributeReleasePolicy();
    policy.setAllowedAttributes(Arrays.asList("1", "2", "3"));
    r.setAttributeReleasePolicy(policy);
    r.getAttributeReleasePolicy().setAttributeFilter(new RegisteredServiceRegexAttributeFilter("\\w+"));

    final RegisteredService r2 = this.dao.save(r);
    final RegisteredService r3 = this.dao.findServiceById(r2.getId());

    assertEquals(r, r2);
    assertEquals(r2, r3);
    assertNotNull(r3.getAttributeReleasePolicy());
    assertEquals(r2.getAttributeReleasePolicy(), r3.getAttributeReleasePolicy());
}
 

import java.util.stream.Stream; //導入依賴的package包/類
public QuadBuilder mirror() {
	if(facingMap.containsKey(last)) {
		Stream<Vector3> stream = Arrays.stream(facingMap.get(last).getVectors());
		switch(last) {
			case DOWN:
			case UP:
				stream.forEach(vec -> {
					vec.subtract(0.5D).rotate(EnumFacing.Axis.Y, 180).add(0.5D);
				});
				break;
			case NORTH:
			case SOUTH:
				stream.forEach(vec -> {
					vec.subtract(0.5D).rotate(EnumFacing.Axis.X, 180).add(0.5D);
				});
				break;
			case EAST:
			case WEST:
				stream.forEach(vec -> {
					vec.subtract(0.5D).rotate(EnumFacing.Axis.Z, 180).add(0.5D);
				});
				break;
		}
	}
	return this;
}
 

import java.util.stream.Stream; //導入依賴的package包/類
@Test
public void findsAllTheBeatles() {
    PerformanceFixed stub = new PerformanceFixed() {
        @Override
        public String getName() {
            throw new UnsupportedOperationException();
        }

        @Override
        public Stream<Artist> getMusicians() {
            return Stream.of(SampleData.theBeatles);
        }
    };

    List<Artist> allMusicians = stub.getAllMusicians().collect(toList());
    assertThat(allMusicians, hasItem(SampleData.theBeatles));
    // There really must be a better way than this
    assertThat(allMusicians, hasItems(SampleData.membersOfTheBeatles.toArray(new Artist[0])));
}
 

import java.util.stream.Stream; //導入依賴的package包/類
@Test
public void should_create_the_correct_stream_on_groupingBy_then_all_max_by_value_and_a_comparator_for_an_empty_stream() {

    // Given
    Stream<String> strings = Stream.empty();

    Collector<String, ?, Set<Map.Entry<String, Long>>> collector =
            CollectorsUtils.groupingByAndAllMaxByValue(
                    Function.<String>identity(),
                    counting(),
                    Comparator.reverseOrder()
            );

    // When
    Set<Map.Entry<String, Long>> result = strings.collect(collector);

    // Then
    assertThat(result).isEmpty();
}
 

import java.util.stream.Stream; //導入依賴的package包/類
private List<Label> getLabels(final Description result) {
    return Stream.of(
            getLabels(result, Epic.class, ResultsUtils::createLabel),
            getLabels(result, Feature.class, ResultsUtils::createLabel),
            getLabels(result, Story.class, ResultsUtils::createLabel),
            getLabels(result, Severity.class, ResultsUtils::createLabel),
            getLabels(result, Owner.class, ResultsUtils::createLabel),
            getLabels(result, Tag.class, this::createLabel)
    ).reduce(Stream::concat).orElseGet(Stream::empty).collect(Collectors.toList());
}
 

import java.util.stream.Stream; //導入依賴的package包/類
@Test
public void canCollectPairsIntoMap() {

    Map<String, String> expectedMap = new HashMap<>();
    expectedMap.put("hello", "world");
    expectedMap.put("six of one", "half a dozen of the other");

    Map<String, String> actualMap = Stream.of(
        entry("hello", "world"),
        entry("six of one", "half a dozen of the other")
    ).collect(toMap());

    assertThat(actualMap, is(expectedMap));
}
 

import java.util.stream.Stream; //導入依賴的package包/類
public void testToImmutableTableMergingNullColumnKey() {
  Collector<Cell<String, String, Integer>, ?, ImmutableTable<String, String, Integer>> collector =
      ImmutableTable.toImmutableTable(Cell::getRowKey, t -> null, Cell::getValue, Integer::sum);
  try {
    Stream.of(Tables.immutableCell("one", "uno", 1)).collect(collector);
    fail("Expected NullPointerException");
  } catch (NullPointerException expected) {
  }
}
 

import java.util.stream.Stream; //導入依賴的package包/類
private <A extends Annotation> void checkInjectedContext(InjectionDevice device, Class<A> annotationClass, boolean includeCommonContext, Class<?>... expectedContextClasses) {
	Set<Object> injectedContext = device.getMethodContext(annotationClass);
	assertNotNull(injectedContext);

	// stream the total set of expected classes, filter out those found in context - if the resulting stream isn't empty we're missing something
	final Predicate<Class<?>> contextHasInstance = klass -> injectedContext.stream().anyMatch(obj -> klass.isInstance(obj));
	Stream<Class<?>> expectedClassStream = Arrays.stream(expectedContextClasses);
	if (includeCommonContext) {
		expectedClassStream = Stream.concat(expectedClassStream, Arrays.stream(COMMON_CONTEXT_CLASSES));
	}
	Optional<Class<?>> missingExpectedContext = expectedClassStream.filter(klass -> !contextHasInstance.test(klass)).findFirst();
	if (missingExpectedContext.isPresent()) {
		Assert.fail("Context missing expected instance of: " + missingExpectedContext.get());
	}
}
 

import java.util.stream.Stream; //導入依賴的package包/類
static Stream<String> dumpResults(
    Stream<Map.Entry<int[], Map<String, String>>> results
) {
    return results
        .map(le ->
                 IntStream.of(le.getKey())
                          .mapToObj(String::valueOf)
                          .collect(joining(","))
                 + "#" +
                 le.getValue().entrySet().stream()
                   .map(e -> e.getKey() + "=" + e.getValue())
                   .collect(joining("|"))
        );
}