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Comparator<T> |

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# 是一个函数接口

# int compare(Object obj)

* 判断对象是否相等,一般作为一些集合框架的比较器

# 默认方法

Comparator<T> thenComparing(Comparator<? super T> other)

<U> Comparator<T> thenComparing(Function<? super T, ? extends U> keyExtractor, Comparator<? super U> keyComparator)

<U extends Comparable<? super U>> Comparator<T> thenComparing(Function<? super T, ? extends U> keyExtractor)

Comparator<T> thenComparingInt(ToIntFunction<? super T> keyExtractor)

Comparator<T> thenComparingLong(ToLongFunction<? super T> keyExtractor)

Comparator<T> thenComparingDouble(ToDoubleFunction<? super T> keyExtractor)

# 提供的静态实现

static <T extends Comparable<? super T>> Comparator<T> reverseOrder()

* 逆序排序

static <T extends Comparable<? super T>> Comparator<T> naturalOrder()

* 自然排序

static <T> Comparator<T> nullsFirst(Comparator<? super T> comparator)

static <T> Comparator<T> nullsLast(Comparator<? super T> comparator)

* null 元素排在头还是尾

static <T, U> Comparator<T> comparing(Function<? super T, ? extends U> keyExtractor, Comparator<? super U> keyComparator)

static <T, U extends Comparable<? super U>> Comparator<T> comparing(Function<? super T, ? extends U> keyExtractor)

static <T> Comparator<T> comparingInt(ToIntFunction<? super T> keyExtractor)

static <T> Comparator<T> comparingLong(ToLongFunction<? super T> keyExtractor)

static<T> Comparator<T> comparingDouble(ToDoubleFunction<? super T> keyExtractor)