Class SetUtil

java.lang.Object

cloud.opencode.base.collections.SetUtil

public final class SetUtil
extends Object

SetUtil - Set Utility Class SetUtil - 集合工具类

Provides factory methods and set operations including union, intersection, difference, and symmetric difference.

提供集合工厂方法和集合运算，包括并集、交集、差集和对称差集。

Features | 主要功能:

• Factory methods for set creation - 集合创建工厂方法
• Set algebra operations (union, intersection, difference) - 集合代数运算
• Power set and combinations - 幂集和组合
• Cartesian product - 笛卡尔积

Usage Examples | 使用示例:

// Create HashSet - 创建 HashSet
Set<String> set = SetUtil.newHashSet("a", "b", "c");

// Union view - 并集视图
SetView<String> union = SetUtil.union(set1, set2);

// Intersection view - 交集视图
SetView<String> intersection = SetUtil.intersection(set1, set2);

// Difference view - 差集视图
SetView<String> difference = SetUtil.difference(set1, set2);

// Power set - 幂集
Set<Set<String>> powerSet = SetUtil.powerSet(set);

Performance | 性能特性:

• Factory methods: O(n) - 工厂方法: O(n)
• Set operations: O(1) creation, O(n) iteration - 集合运算: O(1) 创建, O(n) 遍历
• Power set: O(2^n) - 幂集: O(2^n)

Security | 安全性:

• Thread-safe: No (except concurrent variants) - 线程安全: 否（并发变体除外）
• Null-safe: Yes - 空值安全: 是

Since:

JDK 25, opencode-base-collections V1.0.0

Author:

Leon Soo www.LeonSoo.com

See Also:

• OpenCode.cloud

Method Summary

Modifier and Type	Method	Description
static <E> Set<List<E>>	cartesianProduct(List<? extends Set<? extends E>> sets)	Compute the Cartesian product of sets 笛卡尔积
static <E> Set<List<E>>	cartesianProduct(Set<? extends E>... sets)	Compute the Cartesian product of sets 笛卡尔积
static <E> Set<Set<E>>	combinations(Set<E> set, int size)	Compute combinations of specified size 指定大小的组合
static <E> SetView<E>	difference(Set<E> set1, Set<?> set2)	Return a difference view (set1 - set2) 差集视图
static <E> NavigableSet<E>	filter(NavigableSet<E> unfiltered, Predicate<? super E> predicate)	Return a filtered view of a NavigableSet 过滤 NavigableSet 视图
static <E> Set<E>	filter(Set<E> unfiltered, Predicate<? super E> predicate)	Return a filtered view of a set 过滤视图
static <E> SortedSet<E>	filter(SortedSet<E> unfiltered, Predicate<? super E> predicate)	Return a filtered view of a SortedSet 过滤 SortedSet 视图
static <E> SetView<E>	intersection(Set<E> set1, Set<?> set2)	Return an intersection view of two sets 交集视图
static <E> Set<E>	newConcurrentHashSet()	Create a new concurrent hash set 创建 ConcurrentHashSet
static <E> CopyOnWriteArraySet<E>	newCopyOnWriteArraySet()	Create a new CopyOnWriteArraySet 创建 CopyOnWriteArraySet
static <E> HashSet<E>	newHashSet()	Create a new HashSet 创建 HashSet
static <E> HashSet<E>	newHashSet(E... elements)	Create a new HashSet with initial elements 创建带初始元素的 HashSet
static <E> HashSet<E>	newHashSet(Iterable<? extends E> elements)	Create a new HashSet from an Iterable 从 Iterable 创建 HashSet
static <E> HashSet<E>	newHashSetWithExpectedSize(int expectedSize)	Create a new HashSet with expected size 创建指定容量的 HashSet
static <E> LinkedHashSet<E>	newLinkedHashSet()	Create a new LinkedHashSet 创建 LinkedHashSet
static <E> LinkedHashSet<E>	newLinkedHashSetWithExpectedSize(int expectedSize)	Create a new LinkedHashSet with expected size 创建指定容量的 LinkedHashSet
static <E extends Comparable<E>> TreeSet<E>	newTreeSet()	Create a new TreeSet 创建 TreeSet
static <E> TreeSet<E>	newTreeSet(Comparator<? super E> comparator)	Create a new TreeSet with comparator 带比较器的 TreeSet
static <E> Set<Set<E>>	powerSet(Set<E> set)	Compute the power set (all subsets) 幂集（所有子集）
static <E> SetView<E>	symmetricDifference(Set<? extends E> set1, Set<? extends E> set2)	Return a symmetric difference view 对称差集视图
static <E> NavigableSet<E>	synchronizedNavigableSet(NavigableSet<E> set)	Return a synchronized NavigableSet 同步 NavigableSet
static <E> Set<E>	synchronizedSet(Set<E> set)	Return a synchronized set 同步包装
static <E> SetView<E>	union(Set<? extends E> set1, Set<? extends E> set2)	Return a union view of two sets 并集视图
static <E> NavigableSet<E>	unmodifiableNavigableSet(NavigableSet<E> set)	Return an unmodifiable NavigableSet NavigableSet 视图
static <E> Set<E>	unmodifiableSet(Set<? extends E> set)	Return an unmodifiable set 不可修改包装

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

newHashSet

public static <E> HashSet<E> newHashSet()

Create a new HashSet 创建 HashSet

Type Parameters:

E - element type | 元素类型

Returns:

new HashSet | 新的 HashSet

newHashSet

@SafeVarargs
public static <E> HashSet<E> newHashSet(E... elements)

Create a new HashSet with initial elements 创建带初始元素的 HashSet

Type Parameters:

E - element type | 元素类型

Parameters:

elements - initial elements | 初始元素

Returns:

new HashSet | 新的 HashSet

newHashSet

public static <E> HashSet<E> newHashSet(Iterable<? extends E> elements)

Create a new HashSet from an Iterable 从 Iterable 创建 HashSet

Type Parameters:

E - element type | 元素类型

Parameters:

elements - elements | 元素

Returns:

new HashSet | 新的 HashSet

newHashSetWithExpectedSize

public static <E> HashSet<E> newHashSetWithExpectedSize(int expectedSize)

Create a new HashSet with expected size 创建指定容量的 HashSet

Type Parameters:

E - element type | 元素类型

Parameters:

expectedSize - expected size | 预期大小

Returns:

new HashSet | 新的 HashSet

newLinkedHashSet

public static <E> LinkedHashSet<E> newLinkedHashSet()

Create a new LinkedHashSet 创建 LinkedHashSet

Type Parameters:

E - element type | 元素类型

Returns:

new LinkedHashSet | 新的 LinkedHashSet

newLinkedHashSetWithExpectedSize

public static <E> LinkedHashSet<E> newLinkedHashSetWithExpectedSize(int expectedSize)

Create a new LinkedHashSet with expected size 创建指定容量的 LinkedHashSet

Type Parameters:

E - element type | 元素类型

Parameters:

expectedSize - expected size | 预期大小

Returns:

new LinkedHashSet | 新的 LinkedHashSet

newTreeSet

public static <E extends Comparable<E>> TreeSet<E> newTreeSet()

Create a new TreeSet 创建 TreeSet

Type Parameters:

E - element type | 元素类型

Returns:

new TreeSet | 新的 TreeSet

newTreeSet

public static <E> TreeSet<E> newTreeSet(Comparator<? super E> comparator)

Create a new TreeSet with comparator 带比较器的 TreeSet

Type Parameters:

E - element type | 元素类型

Parameters:

comparator - the comparator | 比较器

Returns:

new TreeSet | 新的 TreeSet

newCopyOnWriteArraySet

public static <E> CopyOnWriteArraySet<E> newCopyOnWriteArraySet()

Create a new CopyOnWriteArraySet 创建 CopyOnWriteArraySet

Type Parameters:

E - element type | 元素类型

Returns:

new CopyOnWriteArraySet | 新的 CopyOnWriteArraySet

newConcurrentHashSet

public static <E> Set<E> newConcurrentHashSet()

Create a new concurrent hash set 创建 ConcurrentHashSet

Type Parameters:

E - element type | 元素类型

Returns:

new concurrent set | 新的并发集合

union

public static <E> SetView<E> union(Set<? extends E> set1,
 Set<? extends E> set2)

Return a union view of two sets 并集视图

Type Parameters:

E - element type | 元素类型

Parameters:

set1 - first set | 第一个集合

set2 - second set | 第二个集合

Returns:

union view | 并集视图

intersection

public static <E> SetView<E> intersection(Set<E> set1,
 Set<?> set2)

Return an intersection view of two sets 交集视图

Type Parameters:

E - element type | 元素类型

Parameters:

set1 - first set | 第一个集合

set2 - second set | 第二个集合

Returns:

intersection view | 交集视图

difference

public static <E> SetView<E> difference(Set<E> set1,
 Set<?> set2)

Return a difference view (set1 - set2) 差集视图

Type Parameters:

E - element type | 元素类型

Parameters:

set1 - first set | 第一个集合

set2 - second set | 第二个集合

Returns:

difference view | 差集视图

symmetricDifference

public static <E> SetView<E> symmetricDifference(Set<? extends E> set1,
 Set<? extends E> set2)

Return a symmetric difference view 对称差集视图

Type Parameters:

E - element type | 元素类型

Parameters:

set1 - first set | 第一个集合

set2 - second set | 第二个集合

Returns:

symmetric difference view | 对称差集视图

cartesianProduct

public static <E> Set<List<E>> cartesianProduct(List<? extends Set<? extends E>> sets)

Compute the Cartesian product of sets 笛卡尔积

Type Parameters:

E - element type | 元素类型

Parameters:

sets - sets to compute product | 要计算积的集合

Returns:

Cartesian product | 笛卡尔积

cartesianProduct

@SafeVarargs
public static <E> Set<List<E>> cartesianProduct(Set<? extends E>... sets)

Compute the Cartesian product of sets 笛卡尔积

Type Parameters:

E - element type | 元素类型

Parameters:

sets - sets to compute product | 要计算积的集合

Returns:

Cartesian product | 笛卡尔积

powerSet

public static <E> Set<Set<E>> powerSet(Set<E> set)

Compute the power set (all subsets) 幂集（所有子集）

Type Parameters:

E - element type | 元素类型

Parameters:

set - the set | 集合

Returns:

power set | 幂集

combinations

public static <E> Set<Set<E>> combinations(Set<E> set,
 int size)

Compute combinations of specified size 指定大小的组合

Type Parameters:

E - element type | 元素类型

Parameters:

set - the set | 集合

size - combination size | 组合大小

Returns:

set of combinations | 组合集合

filter

public static <E> Set<E> filter(Set<E> unfiltered,
 Predicate<? super E> predicate)

Return a filtered view of a set 过滤视图

Type Parameters:

E - element type | 元素类型

Parameters:

unfiltered - the unfiltered set | 未过滤的集合

predicate - the predicate | 谓词

Returns:

filtered view | 过滤视图

filter

public static <E> SortedSet<E> filter(SortedSet<E> unfiltered,
 Predicate<? super E> predicate)

Return a filtered view of a SortedSet 过滤 SortedSet 视图

Type Parameters:

E - element type | 元素类型

Parameters:

unfiltered - the unfiltered set | 未过滤的集合

predicate - the predicate | 谓词

Returns:

filtered view | 过滤视图

filter

public static <E> NavigableSet<E> filter(NavigableSet<E> unfiltered,
 Predicate<? super E> predicate)

Return a filtered view of a NavigableSet 过滤 NavigableSet 视图

Type Parameters:

E - element type | 元素类型

Parameters:

unfiltered - the unfiltered set | 未过滤的集合

predicate - the predicate | 谓词

Returns:

filtered view | 过滤视图

synchronizedSet

public static <E> Set<E> synchronizedSet(Set<E> set)

Return a synchronized set 同步包装

Type Parameters:

E - element type | 元素类型

Parameters:

set - the set | 集合

Returns:

synchronized set | 同步集合

unmodifiableSet

public static <E> Set<E> unmodifiableSet(Set<? extends E> set)

Return an unmodifiable set 不可修改包装

Type Parameters:

E - element type | 元素类型

Parameters:

set - the set | 集合

Returns:

unmodifiable set | 不可修改集合

unmodifiableNavigableSet

public static <E> NavigableSet<E> unmodifiableNavigableSet(NavigableSet<E> set)

Return an unmodifiable NavigableSet NavigableSet 视图

Type Parameters:

E - element type | 元素类型

Parameters:

set - the set | 集合

Returns:

unmodifiable NavigableSet | 不可修改的 NavigableSet

synchronizedNavigableSet

public static <E> NavigableSet<E> synchronizedNavigableSet(NavigableSet<E> set)

Return a synchronized NavigableSet 同步 NavigableSet

Type Parameters:

E - element type | 元素类型

Parameters:

set - the set | 集合

Returns:

synchronized NavigableSet | 同步的 NavigableSet