java.util.stream.Stream.iterate()方法的使用及代码示例

x33g5p2x  于2022-01-16 转载在 其他  
字(9.9k)|赞(0)|评价(0)|浏览(331)

本文整理了Java中java.util.stream.Stream.iterate()方法的一些代码示例,展示了Stream.iterate()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。Stream.iterate()方法的具体详情如下:
包路径:java.util.stream.Stream
类名称:Stream
方法名:iterate

Stream.iterate介绍

暂无

代码示例

canonical example by Tabnine

public List<Integer> findDivisors(int number) {
 return Stream.iterate(1, k -> ++k)
   .limit(number)
   .filter(k -> number % k == 0)
   .collect(Collectors.toList());
}

canonical example by Tabnine

public void printFibonacciSequence(int length) {
 System.out.println(
   Stream.iterate(new long[] {0, 1}, pair -> new long[] {pair[1], pair[0] + pair[1]})
     .limit(length)
     .map(pair -> Long.toString(pair[1]))
     .collect(Collectors.joining(", ")));
}

代码示例来源:origin: RichardWarburton/java-8-lambdas-exercises

static void iterate() {
  Stream.iterate(0, x -> x + 1)
     .limit(5)
     .forEach(System.out::println);
}

代码示例来源:origin: google/guava

public void testZipInfiniteWithInfinite() {
 // zip is doing an infinite zip, but we truncate the result so we can actually test it
 // but we want the zip itself to work
 assertThat(
     Streams.zip(
         Stream.iterate(1, i -> i + 1).map(String::valueOf),
         Stream.iterate(1, i -> i + 1),
         (String str, Integer i) -> str.equals(Integer.toString(i)))
       .limit(100))
   .doesNotContain(false);
}

代码示例来源:origin: google/guava

public void testForEachPair_finiteWithInfinite() {
 List<String> list = new ArrayList<>();
 Streams.forEachPair(
   Stream.of("a", "b", "c"), Stream.iterate(1, i -> i + 1), (a, b) -> list.add(a + ":" + b));
 Truth.assertThat(list).containsExactly("a:1", "b:2", "c:3");
}

代码示例来源:origin: Vedenin/useful-java-links

Stream<Integer> streamFromIterate = Stream.iterate(1, n -> n + 2);
System.out.println("streamFromIterate = " + streamFromIterate.limit(3).collect(Collectors.toList())); // print  streamFromIterate = [1, 3, 5]

代码示例来源:origin: google/guava

public void testZipFiniteWithInfinite() {
 assertThat(
     Streams.zip(
       Stream.of("a", "b", "c"), Stream.iterate(1, i -> i + 1), (a, b) -> a + ":" + b))
   .containsExactly("a:1", "b:2", "c:3")
   .inOrder();
}

代码示例来源:origin: google/error-prone

private Description matchNewClassOrMethodInvocation(
  MethodSymbol symbol, ImmutableList<Commented<ExpressionTree>> arguments, Tree tree) {
 if (symbol.getParameters().isEmpty()) {
  return NO_MATCH;
 }
 SuggestedFix.Builder fix = SuggestedFix.builder();
 forEachPair(
   arguments.stream(),
   Stream.concat(
     symbol.getParameters().stream(),
     Stream.iterate(getLast(symbol.getParameters()), x -> x)),
   (commented, param) -> {
    ImmutableList<Comment> comments =
      commented.afterComments().isEmpty()
        ? commented.beforeComments()
        : commented.afterComments();
    boolean matchStandardForm = !commented.afterComments().isEmpty();
    comments.stream()
      .filter(c -> matchingParamComment(c, param, matchStandardForm))
      .findFirst()
      .ifPresent(c -> fixParamComment(fix, commented, param, c));
   });
 return fix.isEmpty() ? NO_MATCH : describeMatch(tree, fix.build());
}

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

@Test
public void test() {
 RowLevelPolicyChecker.FrontLoadedSampler sampler =
   new RowLevelPolicyChecker.FrontLoadedSampler(10, 2);
 List<Integer> sampled = Stream.iterate(0, i -> i++).limit(1000).filter(i -> sampler.acceptNext()).collect(Collectors.toList());
 Assert.assertTrue(sampled.size() >= 10);
 Assert.assertTrue(sampled.size() < 30);
 // check the first 10 values are the integers from 1 to 9
 Assert.assertEquals(sampled.subList(0, 10), Stream.iterate(0, i -> i++).limit(10).collect(Collectors.toList()));
 // with a very large decay factor, should have very few additional samples
 RowLevelPolicyChecker.FrontLoadedSampler sampler2 =
   new RowLevelPolicyChecker.FrontLoadedSampler(10, 10);
 sampled = Stream.iterate(0, i -> i++).limit(1000).filter(i -> sampler2.acceptNext()).collect(Collectors.toList());
 Assert.assertTrue(sampled.size() >= 10);
 Assert.assertTrue(sampled.size() < 15);
 // check the first 10 values are the integers from 1 to 9
 Assert.assertEquals(sampled.subList(0, 10), Stream.iterate(0, i -> i++).limit(10).collect(Collectors.toList()));
 // with a low decay factor, should have many additional samples
 RowLevelPolicyChecker.FrontLoadedSampler sampler3 =
   new RowLevelPolicyChecker.FrontLoadedSampler(10, 1.2);
 sampled = Stream.iterate(0, i -> i++).limit(1000).filter(i -> sampler3.acceptNext()).collect(Collectors.toList());
 Assert.assertTrue(sampled.size() >= 30);
 Assert.assertTrue(sampled.size() < 100);
 // check the first 10 values are the integers from 1 to 9
 Assert.assertEquals(sampled.subList(0, 10), Stream.iterate(0, i -> i++).limit(10).collect(Collectors.toList()));
}

代码示例来源:origin: google/bundletool

private static ZipPath getUniqueResourcePath(ModuleSplit split) {
  return Stream.iterate(0, i -> i + 1)
    .map(number -> ZipPath.create(String.format(XML_PATH_PATTERN, number)))
    .filter(path -> !split.findEntry(path).isPresent())
    .findFirst()
    .get();
 }
}

代码示例来源:origin: biezhi/learn-java8

public static void main(String[] args) {
  // tuple = (0, 1)
  // next [0] = prev tuple [1]
  // next [1] = prev (tuple [0] + tuple[1])
  Stream.iterate(new Tuple(0, 1), tuple -> new Tuple(tuple.second, tuple.first + tuple.second))
      .limit(20)
      .forEach(tuple -> System.out.println("("+ tuple.first +","+ tuple.second +")"));
}

代码示例来源:origin: aol/cyclops

/**
 * Create a Stream that infiniteable cycles the provided Streamable
 * @param s Streamable to cycle
 * @return New cycling stream
 */
public static <U> Stream<U> cycle(final Streamable<U> s) {
  return Stream.iterate(s.stream(), s1 -> s.stream())
         .flatMap(Function.identity());
}

代码示例来源:origin: aol/cyclops

/**
 * Create a Stream that finitely cycles the provided Streamable, provided number of times
 *
 * <pre>
 * {@code
 * assertThat(StreamUtils.cycle(3,Streamable.of(1,2,2))
              .collect(CyclopsCollectors.toList()),
                equalTo(Arrays.asList(1,2,2,1,2,2,1,2,2)));
 * }
 * </pre>
 * @param s Streamable to cycle
 * @return New cycling stream
 */
public static <U> Stream<U> cycle(final int times, final Streamable<U> s) {
  return Stream.iterate(s.stream(), s1 -> s.stream())
         .limit(times)
         .flatMap(Function.identity());
}

代码示例来源:origin: aol/cyclops

/**
 * Create a Stream that finitely cycles the provided Streamable, provided number of times
 *
 * <pre>
 * {@code
 * assertThat(Streams.cycle(3,Streamable.of(1,2,2))
              .collect(CyclopsCollectors.toList()),
                equalTo(Arrays.asList(1,2,2,1,2,2,1,2,2)));
 * }
 * </pre>
 * @param s Streamable to cycle
 * @return New cycling stream
 */
public static <U> Stream<U> cycle(final long times, final Streamable<U> s) {
  return Stream.iterate(s.stream(), s1 -> s.stream())
         .limit(times)
         .flatMap(Function.identity());
}

代码示例来源:origin: aol/cyclops

@Test
public void compareConcat(){
  List<Integer> oneThousand= Stream.iterate(1,i->i+1).limit(1000).collect(Collectors.toList());
  int total = 0;
  for(int x=0;x<10;x++) {
    total += Stream.concat(oneThousand.stream(),oneThousand.stream()).count();
  }
  long time = System.currentTimeMillis();
  for(int k=0;k<5000;k++)
    count += Stream.concat(oneThousand.stream(),oneThousand.stream()).count();
  long stream = System.currentTimeMillis()-time;
  for(int x=0;x<10;x++) {
    total += ReactiveSeq.concat(oneThousand.stream(),oneThousand.stream()).count();
  }
  long time2 = System.currentTimeMillis();
  for(int k=0;k<5000;k++)
    count += ReactiveSeq.concat(oneThousand.stream(),oneThousand.stream()).count();
  long rs = System.currentTimeMillis()-time2;
  System.out.println("Stream " + stream + " rs with construction " + rs + " count " + count);
}
@Test

代码示例来源:origin: aol/cyclops

@Test
public void compareFlatMap(){
  for(int k=0;k<10;k++)
    count += Stream.generate(()->1).limit(100).flatMap(i->Stream.iterate(1,x->x+i).limit(500)).count();
  long time = System.currentTimeMillis();
  for(int k=0;k<1000;k++)
    count += Stream.generate(()->1).limit(100).flatMap(i->Stream.iterate(1,x->x+i).limit(500)).count();
  long stream = System.currentTimeMillis()-time;
  for(int k=0;k<10;k++)
    count += ReactiveSeq.generate(()->1).limit(100).flatMap(i->Stream.iterate(1,x->x+i).limit(500)).count();
  long time2 = System.currentTimeMillis();
  for(int k=0;k<1000;k++)
    count += ReactiveSeq.generate(()->1).limit(100).flatMap(i->Stream.iterate(1,x->x+i).limit(500)).count();
  long rs = System.currentTimeMillis()-time2;
  System.out.println("Stream " + stream + " rs with construction " + rs + " count " + count);
}
@Test

代码示例来源:origin: neo4j-contrib/neo4j-apoc-procedures

@Test public void testOrderByDate() throws Exception {
  SimpleDateFormat format = formatInUtcZone("yyyy-MM-dd HH:mm:ss");
  try (Transaction tx = db.beginTx()) {
    for (int i = 0 ; i < 8; i++) {
      Node datedNode = db.createNode(() -> "Person");
      datedNode.setProperty("born", format.format(java.util.Date.from(Instant.EPOCH.plus(i, ChronoUnit.DAYS))));
    }
    for (int i = 15 ; i >= 8; i--) {
      Node datedNode = db.createNode(() -> "Person");
      datedNode.setProperty("born", format.format(java.util.Date.from(Instant.EPOCH.plus(i, ChronoUnit.DAYS))));
    }
    tx.success();
  }
  List<java.util.Date> expected = Stream.iterate(Instant.EPOCH, prev -> prev.plus(1, ChronoUnit.DAYS))
      .limit(16)
      .map(java.util.Date::from)
      .sorted()
      .collect(toList());
  List<java.util.Date> actual;
  try (Transaction tx = db.beginTx()) {
    String query = "MATCH (p:Person) RETURN p, apoc.date.parse(p.born,'s') as dob ORDER BY dob ";
    actual = Iterators.asList(db.execute(query).<Long>columnAs("dob")).stream()
        .map(dob -> java.util.Date.from(Instant.ofEpochSecond((long) dob)))
        .collect(toList());
    tx.success();
  }
  assertEquals(expected, actual);
}

代码示例来源:origin: aol/cyclops

Stream.iterate(1,i->i+1).limit(10000)
    .map(i->i*100)
    .map(i -> i * 2)

代码示例来源:origin: aol/cyclops

@Test
public void testIterate() {
  assertThat(just.asSupplier(-10000).iterate(i->i+1).limit(10).sumInt(i->i),equalTo(
          Stream.iterate(just.get(),i->i+1).limit(10).mapToInt(i->i).sum()));
  assertThat(just.asSupplier(-10000).iterate(i->i+1).limit(10).sumInt(i->i),equalTo(145));
}

代码示例来源:origin: aol/cyclops

@Test
public void testIterate() {
  assertThat(just.asSupplier(-10000).iterate(i->i+1).limit(10).sumInt(i->i),equalTo(
          Stream.iterate(just.get(),i->i+1).limit(10).mapToInt(i->i).sum()));
  assertThat(just.asSupplier(-10000).iterate(i->i+1).limit(10).sumInt(i->i),equalTo(145));
}

相关文章