java.lang.Object

java.lang.Record

cloud.opencode.base.collections.Pair<A,B>

Type Parameters:: A - the type of the first element - 第一个元素的类型; B - the type of the second element - 第二个元素的类型
Record Components:: first - the first element - 第一个元素; second - the second element - 第二个元素

All Implemented Interfaces:: Serializable, Map.Entry<A,B>

public record Pair<A,B>(A first, B second) extends Record implements Map.Entry<A,B>, Serializable

Pair - Immutable generic pair of two values Pair - 不可变的泛型二元组

A simple container holding two related values. Implements Map.Entry for seamless interoperability with Java collections.

一个持有两个相关值的简单容器。实现 Map.Entry 以便与 Java 集合无缝互操作。

Features | 主要功能:

Immutable record-based implementation - 基于 record 的不可变实现
Map.Entry compatibility - Map.Entry 兼容
Functional transformations (map, swap) - 函数式变换（map、swap）
Null-safe: allows null values - 空值安全：允许 null 值

Usage Examples | 使用示例:

// Create a pair - 创建二元组
Pair<String, Integer> pair = Pair.of("age", 25);

// Swap elements - 交换元素
Pair<Integer, String> swapped = pair.swap(); // (25, "age")

// Map values - 映射值
Pair<String, String> mapped = pair.mapSecond(String::valueOf); // ("age", "25")

// Use as Map.Entry - 作为 Map.Entry 使用
Map<String, Integer> map = Map.ofEntries(Pair.of("a", 1), Pair.of("b", 2));

Since:

JDK 25, opencode-base-collections V1.0.3

Author:

Leon Soo www.LeonSoo.com

See Also:

Constructor Summary

Constructors

Constructor

Description

Pair(A first, B second)

Creates an instance of a Pair record class.
Method Summary

Modifier and Type

Method

Description

boolean

equals(Object o)

Compares this Pair with another object for equality, compatible with the Map.Entry contract.

A

first()

Returns the value of the first record component.

static <A,B> Pair<A,B>

fromEntry(Map.Entry<A,B> entry)

Creates a Pair from a Map.Entry.

A

getKey()

Returns the first element as the key.

B

getValue()

Returns the second element as the value.

int

hashCode()

Returns a hash code consistent with the Map.Entry contract: Objects.hashCode(getKey()) ^ Objects.hashCode(getValue()).

<C> C

map(BiFunction<? super A, ? super B, ? extends C> fn)

Applies a bi-function to both elements and returns the result.

<C> Pair<C,B>

mapFirst(Function<? super A, ? extends C> fn)

Transforms the first element using the given function.

<C> Pair<A,C>

mapSecond(Function<? super B, ? extends C> fn)

Transforms the second element using the given function.

static <A,B> Pair<A,B>

of(A first, B second)

Creates a new Pair with the given values.

B

second()

Returns the value of the second record component.

B

setValue(B value)

Always throws UnsupportedOperationException since Pair is immutable.

Pair<B,A>

swap()

Returns a new Pair with the elements swapped.

final String

toString()

Returns a string representation of this record class.

Methods inherited from class Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Details
- Pair
  
  public Pair(A first, B second)
  
  Creates an instance of a Pair record class.
  
  Parameters:
  
  first - the value for the first record component
  
  second - the value for the second record component
Method Details
- hashCode
  
  public int hashCode()
  
  Returns a hash code consistent with the Map.Entry contract: Objects.hashCode(getKey()) ^ Objects.hashCode(getValue()). 返回与 Map.Entry 契约一致的哈希码。
  
  Specified by:
  
  hashCode in interface Map.Entry<A,B>
  
  Specified by:
  
  hashCode in class Record
  
  Returns:
  
  the hash code | 哈希码
- equals
  
  public boolean equals(Object o)
  
  Compares this Pair with another object for equality, compatible with the Map.Entry contract. Returns true if the other object is a Map.Entry with equal key and value. 将此 Pair 与另一个对象进行相等性比较，兼容 Map.Entry 契约。
  
  Specified by:
  
  equals in interface Map.Entry<A,B>
  
  Specified by:
  
  equals in class Record
  
  Parameters:
  
  o - the object to compare | 要比较的对象
  
  Returns:
  
  true if equal | 如果相等返回 true
- of
  
  public static <A,B> Pair<A,B> of(A first, B second)
  
  Creates a new Pair with the given values. 使用给定的值创建新的二元组。
  
  Type Parameters:
  
  A - the type of the first element - 第一个元素的类型
  
  B - the type of the second element - 第二个元素的类型
  
  Parameters:
  
  first - the first element (nullable) - 第一个元素（可为 null）
  
  second - the second element (nullable) - 第二个元素（可为 null）
  
  Returns:
  
  a new Pair - 新的二元组
- fromEntry
  
  public static <A,B> Pair<A,B> fromEntry(Map.Entry<A,B> entry)
  
  Creates a Pair from a Map.Entry. 从 Map.Entry 创建二元组。
  
  Type Parameters:
  
  A - the type of the key - 键的类型
  
  B - the type of the value - 值的类型
  
  Parameters:
  
  entry - the map entry - Map 条目
  
  Returns:
  
  a new Pair containing the entry's key and value - 包含条目键值的新二元组
  
  Throws:
  
  NullPointerException - if entry is null - 如果 entry 为 null
- getKey
  
  public A getKey()
  
  Returns the first element as the key. 返回第一个元素作为键。
  
  Specified by:
  
  getKey in interface Map.Entry<A,B>
  
  Returns:
  
  the first element - 第一个元素
- getValue
  
  public B getValue()
  
  Returns the second element as the value. 返回第二个元素作为值。
  
  Specified by:
  
  getValue in interface Map.Entry<A,B>
  
  Returns:
  
  the second element - 第二个元素
- setValue
  
  public B setValue(B value)
  
  Always throws UnsupportedOperationException since Pair is immutable. 始终抛出 UnsupportedOperationException，因为 Pair 是不可变的。
  
  Specified by:
  
  setValue in interface Map.Entry<A,B>
  
  Parameters:
  
  value - ignored - 忽略
  
  Returns:
  
  never returns - 永远不返回
  
  Throws:
  
  UnsupportedOperationException - always - 始终抛出
- swap
  
  public Pair<B,A> swap()
  
  Returns a new Pair with the elements swapped. 返回一个交换了元素的新二元组。
  
  Returns:
  
  a new Pair with first and second swapped - 交换了第一和第二个元素的新二元组
- mapFirst
  
  public <C> Pair<C,B> mapFirst(Function<? super A, ? extends C> fn)
  
  Transforms the first element using the given function. 使用给定函数变换第一个元素。
  
  Type Parameters:
  
  C - the type of the new first element - 新的第一个元素的类型
  
  Parameters:
  
  fn - the mapping function - 映射函数
  
  Returns:
  
  a new Pair with the transformed first element - 变换了第一个元素的新二元组
  
  Throws:
  
  NullPointerException - if fn is null - 如果 fn 为 null
- mapSecond
  
  public <C> Pair<A,C> mapSecond(Function<? super B, ? extends C> fn)
  
  Transforms the second element using the given function. 使用给定函数变换第二个元素。
  
  Type Parameters:
  
  C - the type of the new second element - 新的第二个元素的类型
  
  Parameters:
  
  fn - the mapping function - 映射函数
  
  Returns:
  
  a new Pair with the transformed second element - 变换了第二个元素的新二元组
  
  Throws:
  
  NullPointerException - if fn is null - 如果 fn 为 null
- map
  
  public <C> C map(BiFunction<? super A, ? super B, ? extends C> fn)
  
  Applies a bi-function to both elements and returns the result. 对两个元素应用双参数函数并返回结果。
  
  Type Parameters:
  
  C - the result type - 结果类型
  
  Parameters:
  
  fn - the mapping function - 映射函数
  
  Returns:
  
  the result of applying the function - 函数应用的结果
  
  Throws:
  
  NullPointerException - if fn is null - 如果 fn 为 null
- toString
  
  public final String toString()
  
  Returns a string representation of this record class. The representation contains the name of the class, followed by the name and value of each of the record components.
  
  Specified by:
  
  toString in class Record
  
  Returns:
  
  a string representation of this object
- first
  
  public A first()
  
  Returns the value of the first record component.
  
  Returns:
  
  the value of the first record component
- second
  
  public B second()
  
  Returns the value of the second record component.
  
  Returns:
  
  the value of the second record component

Record Class Pair<A,B>

Constructor Summary

Method Summary

Methods inherited from class Object

Constructor Details

Pair

Method Details

hashCode

equals

of

fromEntry

getKey

getValue

setValue

swap

mapFirst

mapSecond

map

toString

first

second