程序包 java.util.stream

枚举 Collector.Characteristics

java.lang.Object

java.lang.Enum<Collector.Characteristics>

java.util.stream.Collector.Characteristics

所有已实现的接口:

Serializable, Comparable<Collector.Characteristics>

封闭接口:

Collector<T,A,R>

public static enum Collector.Characteristics
extends Enum<Collector.Characteristics>

Characteristics indicating properties of a Collector, which can be used to optimize reduction implementations.

枚举常量概要

枚举常量

枚举常量	说明
CONCURRENT	Indicates that this collector is concurrent, meaning that the result container can support the accumulator function being called concurrently with the same result container from multiple threads.
IDENTITY_FINISH	Indicates that the finisher function is the identity function and can be elided.
UNORDERED	Indicates that the collection operation does not commit to preserving the encounter order of input elements.

方法概要

限定符和类型	方法	说明
static Collector.Characteristics	valueOf(String name)	返回带有指定名称的该类型的枚举常量。 字符串必须与用于声明该类型的枚举常量的 标识符完全匹配。(不允许有多余 的空格字符。)
static Collector.Characteristics[]	values()	按照声明该枚举类型的常量的顺序, 返回 包含这些常量的数组。该方法可用于迭代 常量, 如下所示: for (Collector.Characteristics c : Collector.Characteristics.values()) System.out.println(c);

从类继承的方法 java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

从类继承的方法 java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

枚举常量详细资料

CONCURRENT

public static final Collector.Characteristics CONCURRENT

Indicates that this collector is concurrent, meaning that the result container can support the accumulator function being called concurrently with the same result container from multiple threads.

If a CONCURRENT collector is not also UNORDERED, then it should only be evaluated concurrently if applied to an unordered data source.

UNORDERED

public static final Collector.Characteristics UNORDERED

Indicates that the collection operation does not commit to preserving the encounter order of input elements. (This might be true if the result container has no intrinsic order, such as a Set.)

IDENTITY_FINISH

public static final Collector.Characteristics IDENTITY_FINISH

Indicates that the finisher function is the identity function and can be elided. If set, it must be the case that an unchecked cast from A to R will succeed.

方法详细资料

values

public static Collector.Characteristics[] values()

按照声明该枚举类型的常量的顺序, 返回 包含这些常量的数组。该方法可用于迭代 常量, 如下所示:

for (Collector.Characteristics c : Collector.Characteristics.values())
    System.out.println(c);

返回:

按照声明该枚举类型的常量的顺序返回的包含这些常量的数组

valueOf

public static Collector.Characteristics valueOf(String name)

返回带有指定名称的该类型的枚举常量。 字符串必须与用于声明该类型的枚举常量的 标识符完全匹配。(不允许有多余 的空格字符。)

参数:

name - 要返回的枚举常量的名称。

返回:

返回带有指定名称的枚举常量

抛出:

IllegalArgumentException - 如果该枚举类型没有带有指定名称的常量

NullPointerException - 如果参数为空值