说明
1、ConcurentHashMap结合了HashMap和Hashtable的优点。HashMap不考虑同步，Hashtable考虑同步。但是Hashtable每次同步都要锁定整个结构。
2、ConcurentHashMap锁的方式是稍微细粒度的。ConcurentHashMap将hash表分成16桶(默认值)，如get、put、remove等常用操作只锁定目前需要的桶。
实例
/**
* Creates a new, empty map with the default initial table size (16).
*/
public ConcurrentHashMap() {
}
/**
* Creates a new, empty map with an initial table size
* accommodating the specified number of elements without the need
* to dynamically resize.
*
* @param initialCapacity The implementation performs internal
* sizing to accommodate this many elements.
* @throws IllegalArgumentException if the initial capacity of
* elements is negative
*/
public ConcurrentHashMap(int initialCapacity) {
if (initialCapacity < 0)
throw new IllegalArgumentException();
int cap = ((initialCapacity >= (MAXIMUM_CAPACITY >>> 1)) ?
MAXIMUM_CAPACITY :
tableSizeFor(initialCapacity + (initialCapacity >>> 1) + 1));
this.sizeCtl = cap;
}
/**
* Creates a new map with the same mappings as the given map.
*
* @param m the map
*/
public ConcurrentHashMap(Map m) {
this.sizeCtl = DEFAULT_CAPACITY;
putAll(m);
}
以上就是Java ConcurrentHashMap的介绍，希望对大家有所帮助。更多Java学习指路：Java基础
本教程操作环境：windows7系统、java10版，DELL G3电脑。
