---
aliases: []
tags:
- java
- collection
- map
created: 2026-07-20 20:53:28
modified: 2026-07-20 20:59:35
---
# Java 集åˆæ¡†æž¶ç¬”è®°
---
## 简介
[Java](Java_Note.md) 集åˆç›¸å…³çš„接å£å’Œç±»ï¼Œæ˜¯æ”¾åœ¨ `java.base` 这个「模å—ã€ï¼ˆmoduleï¼‰ä¸ `java.util` 包（Package）下。
```mermaid
classDiagram
class Iterable{
<>
default void forEach(Consumer super T> action)
Interator inerator()
default Spliterator spliterator()
}
class Collection{
<>
boolean add(E e)
boolean addAll(Collection extends E> c)
void clear()
boolean contains(Object o)
boolean containsAll(Collection> c)
boolean isEmpty()
boolean remove(Object o)
boolean removeAll(Collection> c)
default boolean removeIf(Predicate super E> filter)
int size()
Object[] toArray()
T[] toArray(T[] a)
}
class Map{
<>
V put(K key,V value)
void putAll(Map extends K,? extends V> m)
V get(Object key)
default V getOrDefault(Object key, V defaultValue)
V remove(Object key)
default boolean remove(Object key, Object value)
default void forEach(BiConsumer super K, ? super V> action)
boolean isEmpty()
int size()
Collection values()
}
class SequencedCollection{
<>
default void addFirst(E e)
default void addLast(E e)
default E getFirst()
default E getLast()
default E removeFirst()
default E removeLast()
SequencedCollection reversed()
}
class List{
<>
}
class Set{
<>
}
class ArrayList{
}
class LinkedList{
}
class HashSet{
}
class AbstractMap{
boolean containsKey(Object key)
boolean containsValue(Object value)
V get(Object key)
boolean isEmpty()
Set keySet()
Collection values()
V put(K key,V value)
void putAll(Map extends K,? extends V> m)
V remove(Object key)
int size()
}
class HashMap{
}
Iterable <|-- Collection
Collection <|-- List
Iterable <|-- List
SequencedCollection <|-- List
List <|.. ArrayList
List <|.. LinkedList
Collection <|-- Set
Iterable <|-- Set
Set <|.. HashSet
Map <|.. AbstractMap
AbstractMap <|.. HashMap
```
`Collection` 接å£æ˜¯ `Iterable` 接å£çš„å接å£ï¼Œä¹Ÿå°±æ˜¯æ„å‘³ç€ `Collection` 接å£åŠå…¶ã€Œåå™ã€æŽ¥å£éƒ½æ‹¥æœ‰ã€Œè¿ä»£ã€èƒ½åŠ›ã€‚
## List
从 [JDK21](Java_Note.md#JDK21) 开始，`List` 接å£å¤šäº†ä¸€ä¸ªçˆ¶æŽ¥å£ï¼š`SequencedCollection`。
`List` 接å£æ供了四ç§ç”¨äºŽæŒ‰ä½ç½®ï¼ˆç´¢å¼•ï¼‰è®¿é—®åˆ—è¡¨å…ƒç´ çš„æ–¹æ³•ã€‚
* `get(int index)`：通过索引返回元ç´
* `getFirst()`：返回 List ä¸ç¬¬ä¸€ä¸ªå…ƒç´ ，这是 [JDK21](Java_Note.md#JDK21) æ–°åŠ çš„
* `getLast()`：返回 List ä¸æœ€åŽä¸€ä¸ªå…ƒç´ ，这是 [JDK21](Java_Note.md#JDK21) æ–°åŠ çš„
## Set
`Set` 是直接与数å¦ä¸çš„集åˆæ¦‚念对应的接å£ã€‚
> [!info]
>
> As implied by its name, this interface models the mathematical *set* abstraction.
> [!tip]
>
> [Python](../Python/Python_Note.md) ä¸çš„ [集åˆ](../Python/Python_Syntax.md#集åˆ) 就称为 `set`。
`Set` 接å£ç‰¹æ€§ï¼š
* æ— åº
* å…ƒç´ ä¸é‡å¤
## Map
---
## 相关笔记
* [Java 笔记](Java_Note.md)
* [Java 基础è¯æ³•ç¬”è®°](Java_Base_Note.md)
* [Java 资料清å•](Java_Material.md)
* [Java 视频清å•](Java_Videos.md)