Class ImmutableMultiset<E>

java.lang.Object

java.util.AbstractCollection<E>

cloud.opencode.base.collections.immutable.ImmutableMultiset<E>

Type Parameters:

E - element type | 元素类型

All Implemented Interfaces:

Serializable, Iterable<E>, Collection<E>

public final class ImmutableMultiset<E>
extends AbstractCollection<E>
implements Serializable

ImmutableMultiset - Immutable Multiset (Bag) Implementation ImmutableMultiset - 不可变多重集（包）实现

A collection that supports order-independent equality and allows duplicate elements, tracking the count of each element. Cannot be modified after creation.

支持与顺序无关的相等性并允许重复元素的集合，跟踪每个元素的计数。创建后不能修改。

Features | 主要功能:

• Immutable - 不可变
• Thread-safe - 线程安全
• Null-safe (nulls not allowed) - 空值安全（不允许空值）
• Element counting - 元素计数
• O(1) count operations - O(1) 计数操作

Usage Examples | 使用示例:

// Create from elements - 从元素创建
ImmutableMultiset<String> multiset = ImmutableMultiset.of("a", "b", "a", "c", "b", "a");
int count = multiset.count("a"); // Returns 3 - 返回 3

// Create from collection - 从集合创建
ImmutableMultiset<String> multiset = ImmutableMultiset.copyOf(Arrays.asList("x", "x", "y"));

// Use builder - 使用构建器
ImmutableMultiset<String> multiset = ImmutableMultiset.<String>builder()
    .add("a")
    .addAll(Arrays.asList("b", "c"))
    .setCount("a", 3)
    .build();

// Query operations - 查询操作
Set<String> elementSet = multiset.elementSet(); // Unique elements - 唯一元素
int totalSize = multiset.size(); // Total count of all elements - 所有元素的总数

Performance | 性能特性:

• count: O(1) - count: O(1)
• contains: O(1) - contains: O(1)
• add/remove: Not supported (immutable) - add/remove: 不支持（不可变）
• iteration: O(n) where n is total size - iteration: O(n)，其中n是总大小

Security | 安全性:

• Thread-safe: Yes (immutable) - 线程安全: 是（不可变）
• Null-safe: Yes (nulls not allowed) - 空值安全: 是（不允许空值）

Since:

JDK 25, opencode-base-collections V1.0.0

Author:

Leon Soo www.LeonSoo.com

See Also:

• OpenCode.cloud
• Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static final class	ImmutableMultiset.Builder<E>	Builder for ImmutableMultiset ImmutableMultiset 构建器
static interface	ImmutableMultiset.Entry<E>	Entry interface for multiset entries 多重集条目的条目接口

Method Summary

Modifier and Type	Method	Description
boolean	add(E e)
boolean	addAll(Collection<? extends E> c)
static <E> ImmutableMultiset.Builder<E>	builder()	Return a new builder.
void	clear()
boolean	contains(Object o)
static <E> ImmutableMultiset<E>	copyOf(Iterable<? extends E> elements)	Return an immutable multiset containing the elements of the given iterable.
static <E> ImmutableMultiset<E>	copyOf(Collection<? extends E> elements)	Return an immutable multiset containing the elements of the given collection.
int	count(Object element)	Return the count of the given element in this multiset.
Set<E>	elementSet()	Return the set of distinct elements in this multiset.
Set<ImmutableMultiset.Entry<E>>	entrySet()	Return the set of entries with elements and their counts.
boolean	equals(Object o)
int	hashCode()
boolean	isEmpty()
Iterator<E>	iterator()
static <E> ImmutableMultiset<E>	of()	Return an empty immutable multiset.
static <E> ImmutableMultiset<E>	of(E e1)	Return an immutable multiset containing the given element.
static <E> ImmutableMultiset<E>	of(E... elements)	Return an immutable multiset containing the given elements.
static <E> ImmutableMultiset<E>	of(E e1, E e2)	Return an immutable multiset containing the given elements.
boolean	remove(Object o)
boolean	removeAll(Collection<?> c)
boolean	retainAll(Collection<?> c)
int	size()
Object[]	toArray()
<T> T[]	toArray(T[] a)
String	toString()

Methods inherited from class AbstractCollection

containsAll

Methods inherited from class Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface Collection

parallelStream, removeIf, spliterator, stream, toArray

Methods inherited from interface Iterable

forEach

Method Details

of

public static <E> ImmutableMultiset<E> of()

Return an empty immutable multiset. 返回空不可变多重集。

Type Parameters:

E - element type | 元素类型

Returns:

empty immutable multiset | 空不可变多重集

of

public static <E> ImmutableMultiset<E> of(E e1)

Return an immutable multiset containing the given element. 返回包含给定元素的不可变多重集。

Type Parameters:

E - element type | 元素类型

Parameters:

e1 - the element | 元素

Returns:

immutable multiset | 不可变多重集

of

public static <E> ImmutableMultiset<E> of(E e1,
 E e2)

Return an immutable multiset containing the given elements. 返回包含给定元素的不可变多重集。

Type Parameters:

E - element type | 元素类型

Parameters:

e1 - first element | 第一个元素

e2 - second element | 第二个元素

Returns:

immutable multiset | 不可变多重集

of

@SafeVarargs
public static <E> ImmutableMultiset<E> of(E... elements)

Return an immutable multiset containing the given elements. 返回包含给定元素的不可变多重集。

Type Parameters:

E - element type | 元素类型

Parameters:

elements - the elements | 元素

Returns:

immutable multiset | 不可变多重集

copyOf

public static <E> ImmutableMultiset<E> copyOf(Collection<? extends E> elements)

Return an immutable multiset containing the elements of the given collection. 返回包含给定集合元素的不可变多重集。

Type Parameters:

E - element type | 元素类型

Parameters:

elements - the elements | 元素

Returns:

immutable multiset | 不可变多重集

copyOf

public static <E> ImmutableMultiset<E> copyOf(Iterable<? extends E> elements)

Return an immutable multiset containing the elements of the given iterable. 返回包含给定可迭代对象元素的不可变多重集。

Type Parameters:

E - element type | 元素类型

Parameters:

elements - the elements | 元素

Returns:

immutable multiset | 不可变多重集

builder

public static <E> ImmutableMultiset.Builder<E> builder()

Return a new builder. 返回新构建器。

Type Parameters:

E - element type | 元素类型

Returns:

builder | 构建器

count

public int count(Object element)

Return the count of the given element in this multiset. 返回此多重集中给定元素的计数。

Parameters:

element - the element to count | 要计数的元素

Returns:

the count of the element, or 0 if not present | 元素的计数，如果不存在则为0

elementSet

public Set<E> elementSet()

Return the set of distinct elements in this multiset. 返回此多重集中的不同元素集。

Returns:

unmodifiable set of distinct elements | 不可修改的不同元素集

entrySet

public Set<ImmutableMultiset.Entry<E>> entrySet()

Return the set of entries with elements and their counts. 返回包含元素及其计数的条目集。

Returns:

unmodifiable set of entries | 不可修改的条目集

iterator

public Iterator<E> iterator()

Specified by:

iterator in interface Collection<E>

Specified by:

iterator in interface Iterable<E>

Specified by:

iterator in class AbstractCollection<E>

size

public int size()

Specified by:

size in interface Collection<E>

Specified by:

size in class AbstractCollection<E>

contains

public boolean contains(Object o)

Specified by:

contains in interface Collection<E>

Overrides:

contains in class AbstractCollection<E>

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Collection<E>

Overrides:

isEmpty in class AbstractCollection<E>

toArray

public Object[] toArray()

Specified by:

toArray in interface Collection<E>

Overrides:

toArray in class AbstractCollection<E>

toArray

public <T> T[] toArray(T[] a)

Specified by:

toArray in interface Collection<E>

Overrides:

toArray in class AbstractCollection<E>

add

public boolean add(E e)

Specified by:

add in interface Collection<E>

Overrides:

add in class AbstractCollection<E>

remove

public boolean remove(Object o)

Specified by:

remove in interface Collection<E>

Overrides:

remove in class AbstractCollection<E>

addAll

public boolean addAll(Collection<? extends E> c)

Specified by:

addAll in interface Collection<E>

Overrides:

addAll in class AbstractCollection<E>

removeAll

public boolean removeAll(Collection<?> c)

Specified by:

removeAll in interface Collection<E>

Overrides:

removeAll in class AbstractCollection<E>

retainAll

public boolean retainAll(Collection<?> c)

Specified by:

retainAll in interface Collection<E>

Overrides:

retainAll in class AbstractCollection<E>

clear

public void clear()

Specified by:

clear in interface Collection<E>

Overrides:

clear in class AbstractCollection<E>

equals

public boolean equals(Object o)

Specified by:

equals in interface Collection<E>

Overrides:

equals in class Object

hashCode

public int hashCode()

Specified by:

hashCode in interface Collection<E>

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class AbstractCollection<E>