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图床更新，请注意查看readme

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2022-07-24 19:36:01 +08:00
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commit 130c2ff4bf
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docs/Java/collection/HashMap-JDK7源码讲解.md
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@@ -8,7 +8,7 @@ categories:
- HashMap
keywords: Java集合，HashMap。
description: HashMap-JDK7源码讲解。
cover: 'https://npm.elemecdn.com/lql_static@latest/logo/java.png'
cover: 'https://upyunimg.imlql.cn/lql_static@latest/logo/java.png'
abbrlink: f1f58db2
date: 2020-11-01 10:21:58
---
@@ -202,7 +202,7 @@ hadoop2
大致是这样的一个结构
<img src="https://npm.elemecdn.com/youthlql@1.0.8/Java_collection/HashMap/JDK7/0001.png">
<img src="https://upyunimg.imlql.cn/youthlql@1.0.8/Java_collection/HashMap/JDK7/0001.png">
- 每个链表就算哈希表的桶（bucket）
- 链表的节点值就算一个键值对
@@ -398,7 +398,7 @@ static class Entry<K,V> implements Map.Entry<K,V> {
`HashMap`中的数组元素 & 链表节点 采用 `Entry`类实现
<img src="https://npm.elemecdn.com/youthlql@1.0.8/Java_collection/HashMap/JDK7/0001.png">
<img src="https://upyunimg.imlql.cn/youthlql@1.0.8/Java_collection/HashMap/JDK7/0001.png">
1、一个正方形代表一个Entry对象，同时也代表一个键值对。
@@ -769,15 +769,15 @@ void transfer(Entry[] newTable, boolean rehash) {
大概画了一下图：
<img src="https://npm.elemecdn.com/youthlql@1.0.8/Java_collection/HashMap/JDK7/0002.png"/>
<img src="https://upyunimg.imlql.cn/youthlql@1.0.8/Java_collection/HashMap/JDK7/0002.png"/>
<img src="https://npm.elemecdn.com/youthlql@1.0.8/Java_collection/HashMap/JDK7/0003.png">
<img src="https://upyunimg.imlql.cn/youthlql@1.0.8/Java_collection/HashMap/JDK7/0003.png">
<img src="https://npm.elemecdn.com/youthlql@1.0.8/Java_collection/HashMap/JDK7/0004.png">
<img src="https://upyunimg.imlql.cn/youthlql@1.0.8/Java_collection/HashMap/JDK7/0004.png">
<img src="https://npm.elemecdn.com/youthlql@1.0.8/Java_collection/HashMap/JDK7/0005.png">
<img src="https://upyunimg.imlql.cn/youthlql@1.0.8/Java_collection/HashMap/JDK7/0005.png">
@@ -871,7 +871,7 @@ void transfer(Entry[] newTable, boolean rehash) {
**hashmap初始状态**
<img src="https://npm.elemecdn.com/youthlql@1.0.8/Java_collection/HashMap/JDK7/0006.png">
<img src="https://upyunimg.imlql.cn/youthlql@1.0.8/Java_collection/HashMap/JDK7/0006.png">
@@ -897,7 +897,7 @@ void transfer(Entry[] newTable, boolean rehash) {
**两个线程调用完毕之后，hashmap目前是这样的。**
<img src="https://npm.elemecdn.com/youthlql@1.0.8/Java_collection/HashMap/JDK7/0007.png">
<img src="https://upyunimg.imlql.cn/youthlql@1.0.8/Java_collection/HashMap/JDK7/0007.png">
@@ -918,9 +918,9 @@ void transfer(Entry[] newTable, boolean rehash) {
3、来看下此时内存里的状态
<img src="https://npm.elemecdn.com/youthlql@1.0.8/Java_collection/HashMap/JDK7/0008.png"/>
<img src="https://upyunimg.imlql.cn/youthlql@1.0.8/Java_collection/HashMap/JDK7/0008.png"/>
<img src="https://npm.elemecdn.com/youthlql@1.0.8/Java_collection/HashMap/JDK7/0009.png">
<img src="https://upyunimg.imlql.cn/youthlql@1.0.8/Java_collection/HashMap/JDK7/0009.png">
## 步骤4
@@ -957,7 +957,7 @@ void transfer(Entry[] newTable, boolean rehash) {
2、线程2直接**扩容完毕**，那么完成后的状态是这样【假设e2和e3还是hash到同一个位置】
<img src="https://npm.elemecdn.com/youthlql@1.0.8/Java_collection/HashMap/JDK7/0010.png">
<img src="https://upyunimg.imlql.cn/youthlql@1.0.8/Java_collection/HashMap/JDK7/0010.png">
3、线程1还是原来的状态
@@ -967,11 +967,11 @@ void transfer(Entry[] newTable, boolean rehash) {
目前两个线程里的新数组是这样的
<img src="https://npm.elemecdn.com/youthlql@1.0.8/Java_collection/HashMap/JDK7/0011.png">
<img src="https://upyunimg.imlql.cn/youthlql@1.0.8/Java_collection/HashMap/JDK7/0011.png">
为了方便后面观看，我画成这样。
<img src="https://npm.elemecdn.com/youthlql@1.0.8/Java_collection/HashMap/JDK7/0012.png">
<img src="https://upyunimg.imlql.cn/youthlql@1.0.8/Java_collection/HashMap/JDK7/0012.png">
@@ -1015,7 +1015,7 @@ void transfer(Entry[] newTable, boolean rehash) {
也就变成了下面这个样子。
<img src="https://npm.elemecdn.com/youthlql@1.0.8/Java_collection/HashMap/JDK7/0013.png">
<img src="https://upyunimg.imlql.cn/youthlql@1.0.8/Java_collection/HashMap/JDK7/0013.png">
@@ -1061,7 +1061,7 @@ void transfer(Entry[] newTable, boolean rehash) {
执行完，变成这样。
<img src="https://npm.elemecdn.com/youthlql@1.0.8/Java_collection/HashMap/JDK7/0014.png">
<img src="https://upyunimg.imlql.cn/youthlql@1.0.8/Java_collection/HashMap/JDK7/0014.png">
@@ -1077,7 +1077,7 @@ void transfer(Entry[] newTable, boolean rehash) {
3、执行pos_3： newTable[i] = e得到 newTable1[3] == e2
<img src="https://npm.elemecdn.com/youthlql@1.0.8/Java_collection/HashMap/JDK7/0015.png">
<img src="https://upyunimg.imlql.cn/youthlql@1.0.8/Java_collection/HashMap/JDK7/0015.png">
这样就形成了循环链表，再get()数据就会陷入死循环。