Java : Spliterator 示例

Java 中的 Spliterator (Java SE 23 & JDK 23) 及其示例。
您将找到大多数 Spliterator<T> 方法的代码示例。

注解 :

本文可能使用了翻译软件以方便阅读。另请查看英文原文。

简介

用于遍历和分割源元素的对象。Spliterator 所涵盖的元素源可以是数组、Collection、IO 通道或生成器函数。 (机器翻译)

Class diagram

final var list = List.of("aaa", "bbb", "ccc");
System.out.println(list); // [aaa, bbb, ccc]
System.out.println(list.size()); // 3

final var spliterator = list.spliterator();

System.out.println("-- forEachRemaining --");
spliterator.forEachRemaining(s -> {
    System.out.println(s);
});

// Result
// ↓
//-- forEachRemaining --
//aaa
//bbb
//ccc

final var list = List.of("a", "b", "c", "d", "e");
System.out.println(list); // [a, b, c, d, e]
System.out.println(list.size()); // 5

final var s1 = list.spliterator();
System.out.println("s1 size : " + s1.estimateSize()); // s1 size : 5

final var s2 = s1.trySplit();
System.out.println("s1 size : " + s1.estimateSize()); // s1 size : 3
System.out.println("s2 size : " + s2.estimateSize()); // s2 size : 2

System.out.println("-- s1 --");
s1.forEachRemaining(System.out::println);

// Result
// ↓
//-- s1 --
//c
//d
//e

System.out.println("-- s2 --");
s2.forEachRemaining(System.out::println);

// Result
// ↓
//-- s2 --
//a
//b

Fields

static final int CONCURRENT

特征值表示元素源可以被多个线程安全地同时修改（允许添加、替换和/或删除），而无需外部同步。 (机器翻译)

final var queue = new ConcurrentLinkedQueue<String>();
queue.add("a");
queue.add("b");

final var spliterator = queue.spliterator();

System.out.printf("0x%x%n", spliterator.characteristics()); // 0x1110

System.out.printf("CONCURRENT : 0x%x%n", Spliterator.CONCURRENT); // CONCURRENT : 0x1000
System.out.printf("NONNULL : 0x%x%n", Spliterator.NONNULL); // NONNULL : 0x100
System.out.printf("ORDERED : 0x%x%n", Spliterator.ORDERED); // ORDERED : 0x10

static final int DISTINCT

特征值表示，对于每对遇到的元素 x，y，！x.equals(y)。 (机器翻译)

final var set = new HashSet<String>();
set.add("a");
set.add("b");

final var spliterator = set.spliterator();

System.out.printf("0x%x%n", spliterator.characteristics()); // 0x41

System.out.printf("SIZED : 0x%x%n", Spliterator.SIZED); // SIZED : 0x40
System.out.printf("DISTINCT : 0x%x%n", Spliterator.DISTINCT); // DISTINCT : 0x1

static final int IMMUTABLE

特征值表示元素源不能从结构上进行修改；也就是说，不能添加、替换或删除元素，因此在遍历过程中不能发生此类更改。 (机器翻译)

final var list = new CopyOnWriteArrayList<String>();
list.add("a");
list.add("b");

final var spliterator = list.spliterator();

System.out.printf("0x%x%n", spliterator.characteristics()); // 0x4450

System.out.printf("SUBSIZED : 0x%x%n", Spliterator.SUBSIZED); // SUBSIZED : 0x4000
System.out.printf("IMMUTABLE : 0x%x%n", Spliterator.IMMUTABLE); // IMMUTABLE : 0x400
System.out.printf("SIZED : 0x%x%n", Spliterator.SIZED); // SIZED : 0x40
System.out.printf("ORDERED : 0x%x%n", Spliterator.ORDERED); // ORDERED : 0x10

static final int NONNULL

特征值表示源保证遇到的元素不会为空。 (机器翻译)

final var deque = new ArrayDeque<String>();
deque.add("a");
deque.add("b");
//deque.add(null); // NullPointerException

final var spliterator = deque.spliterator();

System.out.printf("0x%x%n", spliterator.characteristics()); // 0x4150

System.out.printf("SUBSIZED : 0x%x%n", Spliterator.SUBSIZED); // SUBSIZED : 0x4000
System.out.printf("NONNULL : 0x%x%n", Spliterator.NONNULL); // NONNULL : 0x100
System.out.printf("SIZED : 0x%x%n", Spliterator.SIZED); // SIZED : 0x40
System.out.printf("ORDERED : 0x%x%n", Spliterator.ORDERED); // ORDERED : 0x10

static final int ORDERED

表示为元素定义了遭遇顺序的特征值。 (机器翻译)

final var list = new ArrayList<String>();
list.add("a");
list.add("b");

final var spliterator = list.spliterator();

System.out.printf("0x%x%n", spliterator.characteristics()); // 0x4050

System.out.printf("SUBSIZED : 0x%x%n", Spliterator.SUBSIZED); // SUBSIZED : 0x4000
System.out.printf("SIZED : 0x%x%n", Spliterator.SIZED); // SIZED : 0x40
System.out.printf("ORDERED : 0x%x%n", Spliterator.ORDERED); // ORDERED : 0x10

static final int SIZED

特征值表示在遍历或拆分之前从estimateSize（）返回的值代表一个有限的大小，在没有结构源修改的情况下，它代表完整遍历所遇到的元素数量的精确计数。 (机器翻译)

final var list = new ArrayList<String>();
list.add("a");
list.add("b");

final var spliterator = list.spliterator();

System.out.printf("0x%x%n", spliterator.characteristics()); // 0x4050

System.out.printf("SUBSIZED : 0x%x%n", Spliterator.SUBSIZED); // SUBSIZED : 0x4000
System.out.printf("SIZED : 0x%x%n", Spliterator.SIZED); // SIZED : 0x40
System.out.printf("ORDERED : 0x%x%n", Spliterator.ORDERED); // ORDERED : 0x10

static final int SORTED

特征值表示遭遇顺序遵循定义的排序顺序。 (机器翻译)

final var set = new TreeSet<String>();
set.add("a");
set.add("b");

final var spliterator = set.spliterator();

System.out.printf("0x%x%n", spliterator.characteristics()); // 0x55

System.out.printf("SIZED : 0x%x%n", Spliterator.SIZED); // SIZED : 0x40
System.out.printf("ORDERED : 0x%x%n", Spliterator.ORDERED); // ORDERED : 0x10
System.out.printf("SORTED : 0x%x%n", Spliterator.SORTED); // SORTED : 0x4
System.out.printf("DISTINCT : 0x%x%n", Spliterator.DISTINCT); // DISTINCT : 0x1

static final int SUBSIZED

特征值表示由 trySplit() 产生的所有 Spliterator 都将是 SIZED 和 SUBSIZED。 (机器翻译)

final var list = new ArrayList<String>();
list.add("a");
list.add("b");

final var spliterator = list.spliterator();

System.out.printf("0x%x%n", spliterator.characteristics()); // 0x4050

System.out.printf("SUBSIZED : 0x%x%n", Spliterator.SUBSIZED); // SUBSIZED : 0x4000
System.out.printf("SIZED : 0x%x%n", Spliterator.SIZED); // SIZED : 0x40
System.out.printf("ORDERED : 0x%x%n", Spliterator.ORDERED); // ORDERED : 0x10

Methods

int characteristics ()

返回此 Spliterator 及其元素的一组特征。 (机器翻译)

final var set = new HashSet<String>();
set.add("a");
set.add("b");

final var spliterator = set.spliterator();

System.out.printf("0x%x%n", spliterator.characteristics()); // 0x41

System.out.printf("SIZED : 0x%x%n", Spliterator.SIZED); // SIZED : 0x40
System.out.printf("DISTINCT : 0x%x%n", Spliterator.DISTINCT); // DISTINCT : 0x1

System.out.println(spliterator.hasCharacteristics(Spliterator.SIZED)); // true
System.out.println(spliterator.hasCharacteristics(Spliterator.DISTINCT)); // true
System.out.println(spliterator.hasCharacteristics(Spliterator.ORDERED)); // false

long estimateSize ()

返回 forEachRemaining(java.util.function.Consumer<? super T>) 遍历会遇到的元素数量的估计值，如果无限、未知或计算成本太高，则返回 Long.MAX_VALUE。 (机器翻译)

final var list = List.of("a", "b", "c", "d", "e");
System.out.println(list); // [a, b, c, d, e]
System.out.println(list.size()); // 5

final var spliterator = list.spliterator();
System.out.println(spliterator.estimateSize()); // 5
System.out.println(spliterator.getExactSizeIfKnown()); // 5

final var queue = new ConcurrentLinkedQueue<String>();
queue.add("a");
queue.add("b");
queue.add("c");

System.out.println(queue); // [a, b, c]
System.out.println(queue.size()); // 3

final var spliterator = queue.spliterator();
System.out.println(spliterator.estimateSize() == Long.MAX_VALUE); // true
System.out.println(spliterator.getExactSizeIfKnown()); // -1

default void forEachRemaining (Consumer<? super T> action)

在当前线程中按顺序对每个剩余元素执行给定的操作，直到所有元素都已处理或操作引发异常。 (机器翻译)

final var list = List.of("aaa", "bbb", "ccc");
System.out.println(list); // [aaa, bbb, ccc]
System.out.println(list.size()); // 3

final var spliterator = list.spliterator();

System.out.println("-- forEachRemaining --");
spliterator.forEachRemaining(s -> {
    System.out.println(s);
});

// Result
// ↓
//-- forEachRemaining --
//aaa
//bbb
//ccc

default Comparator<? super T> getComparator ()

如果此 Spliterator 的源由 Comparator 排序，则返回该 Comparator。 (机器翻译)

final var set = new TreeSet<String>();
set.add("c");
set.add("d");
set.add("a");
set.add("b");

System.out.println(set); // [a, b, c, d]

final var spliterator = set.spliterator();
final var comparator = spliterator.getComparator();

System.out.println(comparator); // null

final Comparator<String> reverse = Comparator.reverseOrder();

final var set = new TreeSet<>(reverse);
set.add("c");
set.add("d");
set.add("a");
set.add("b");

System.out.println(set); // [d, c, b, a]

final var spliterator = set.spliterator();
final var comparator = spliterator.getComparator();
System.out.println(comparator == reverse); // true

final var list = List.of("a", "b", "c");
System.out.println(list); // [a, b, c]

final var spliterator = list.spliterator();

try {
    var _ = spliterator.getComparator();
} catch (IllegalStateException e) {
    System.out.println("IllegalStateException!");
}

// Result
// ↓
//IllegalStateException!

default long getExactSizeIfKnown ()

如果此 Spliterator 是 SIZED，则返回estimateSize() 的便捷方法，否则返回 -1。 (机器翻译)

final var list = List.of("a", "b", "c", "d", "e");
System.out.println(list); // [a, b, c, d, e]
System.out.println(list.size()); // 5

final var spliterator = list.spliterator();
System.out.println(spliterator.estimateSize()); // 5
System.out.println(spliterator.getExactSizeIfKnown()); // 5

final var queue = new ConcurrentLinkedQueue<String>();
queue.add("a");
queue.add("b");
queue.add("c");

System.out.println(queue); // [a, b, c]
System.out.println(queue.size()); // 3

final var spliterator = queue.spliterator();
System.out.println(spliterator.estimateSize() == Long.MAX_VALUE); // true
System.out.println(spliterator.getExactSizeIfKnown()); // -1

default boolean hasCharacteristics (int characteristics)

如果此 Spliterator 的 Characteristics() 包含所有给定的特征，则返回 True。 (机器翻译)

final var set = new HashSet<String>();
set.add("a");
set.add("b");

final var spliterator = set.spliterator();

System.out.printf("0x%x%n", spliterator.characteristics()); // 0x41

System.out.printf("SIZED : 0x%x%n", Spliterator.SIZED); // SIZED : 0x40
System.out.printf("DISTINCT : 0x%x%n", Spliterator.DISTINCT); // DISTINCT : 0x1

System.out.println(spliterator.hasCharacteristics(Spliterator.SIZED)); // true
System.out.println(spliterator.hasCharacteristics(Spliterator.DISTINCT)); // true
System.out.println(spliterator.hasCharacteristics(Spliterator.ORDERED)); // false

boolean tryAdvance (Consumer<? super T> action)

如果存在剩余元素：对其执行给定的操作，返回 true；否则返回 false。 (机器翻译)

final var list = List.of("aaa", "bbb", "ccc");
final var spliterator = list.spliterator();

System.out.println("-- tryAdvance --");
final var ret1 = spliterator.tryAdvance(System.out::println);
System.out.println("ret : " + ret1);

System.out.println("-- tryAdvance --");
final var ret2 = spliterator.tryAdvance(System.out::println);
System.out.println("ret : " + ret2);

System.out.println("-- tryAdvance --");
final var ret3 = spliterator.tryAdvance(System.out::println);
System.out.println("ret : " + ret3);

System.out.println("-- tryAdvance --");
final var ret4 = spliterator.tryAdvance(System.out::println);
System.out.println("ret : " + ret4);

// Result
// ↓
//-- tryAdvance --
//aaa
//ret : true
//-- tryAdvance --
//bbb
//ret : true
//-- tryAdvance --
//ccc
//ret : true
//-- tryAdvance --
//ret : false

Spliterator<T> trySplit ()

如果此 Spliterator 可被分割，则返回一个涵盖元素的 Spliterator，而从此方法返回时，这些元素将不会被此 Spliterator 覆盖。 (机器翻译)

final var list = List.of("a", "b", "c", "d", "e");
System.out.println(list); // [a, b, c, d, e]
System.out.println(list.size()); // 5

final var s1 = list.spliterator();
System.out.println("s1 size : " + s1.estimateSize()); // s1 size : 5

final var s2 = s1.trySplit();
System.out.println("s1 size : " + s1.estimateSize()); // s1 size : 3
System.out.println("s2 size : " + s2.estimateSize()); // s2 size : 2

System.out.println("-- s1 --");
s1.forEachRemaining(System.out::println);

// Result
// ↓
//-- s1 --
//c
//d
//e

System.out.println("-- s2 --");
s2.forEachRemaining(System.out::println);

// Result
// ↓
//-- s2 --
//a
//b

API 示例

Java : Spliterator 示例

简介

Fields

static final int CONCURRENT

static final int DISTINCT

static final int IMMUTABLE

static final int NONNULL

static final int ORDERED

static final int SIZED

static final int SORTED

static final int SUBSIZED

Methods

int characteristics ()

long estimateSize ()

default void forEachRemaining (Consumer<? super T> action)

default Comparator<? super T> getComparator ()

default long getExactSizeIfKnown ()

default boolean hasCharacteristics (int characteristics)

boolean tryAdvance (Consumer<? super T> action)

Spliterator<T> trySplit ()

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