HashMap扩容以及ConcurrentHashMap扩容机制

﹏ヽ暗。殇╰゛Y 2023-10-03 14:42 8阅读 0赞

#### HashMap扩容以及ConcurrentHashMap扩容机制 ####

*  HashMap
 *   *  1.7
     *  1.8
 *  ConcurrentHashMap
 *   *  1.7
     *  1.8

## HashMap ##

### 1.7 ###

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIxMDQwNTU5_size_16_color_FFFFFF_t_70]

void transfer(Entry[] newTable) {
            
        // 1.7 的hashmap 数组+链表
        // 获取到旧表
        Entry[] src = table;
        // 获取到新表的长度(数组的长度)
        int newCapacity = newTable.length;    
        // 遍历旧表的每一条链表
        for (int j = 0; j < src.length; j++) {
         //遍历旧的Entry数组    
            Entry<K, V> e = src[j];             //取得旧Entry数组的每个元素    
            if (e != null) {
           
                // 释放掉旧的Entry数组的对象引用
                src[j] = null;
                // 遍历链表中的元素进行转移到新表中(头插法转移元素)
                do {
            
                    Entry<K, V> next = e.next;  
                    // 重新计算每个元素在数组中的位置！！      
                    int i = indexFor(e.hash, newCapacity); 
                    e.next = newTable[i];
                    newTable[i] = e;
                    e = next;
                } while (e != null);    
            }    
        }    
    }

### 1.8 ###

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIxMDQwNTU5_size_16_color_FFFFFF_t_70 1]

## ConcurrentHashMap ##

### 1.7 ###

### 1.8 ###

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIxMDQwNTU5_size_16_color_FFFFFF_t_70 2]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIxMDQwNTU5_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/ac479a76afd344c5ba8eba69892a3a54.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIxMDQwNTU5,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIxMDQwNTU5_size_16_color_FFFFFF_t_70 1]: https://img-blog.csdnimg.cn/b25570573d654027bddd648f909f0abf.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIxMDQwNTU5,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIxMDQwNTU5_size_16_color_FFFFFF_t_70 2]: https://img-blog.csdnimg.cn/22b50be5f1c04ee79315b1e643f606b7.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIxMDQwNTU5,size_16,color_FFFFFF,t_70