說明
1、ConcurentHashMap結合了HashMap和Hashtable的優點。 HashMap不考慮同步，Hashtable考慮同步。但是Hashtable每次同步都要鎖定整個結構。
2、ConcurentHashMap鎖定的方式是稍微細粒度的。 ConcurentHashMap將hash表分成16桶(預設值)，如get、put、remove等常用操作只鎖定目前需要的桶子。
實例
/**
* 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<? extends K, ? extends V> m) {
this.sizeCtl = DEFAULT_CAPACITY;
putAll(m);
}以上是如何在Java中使用ConcurrentHashMap？的詳細內容。更多資訊請關注PHP中文網其他相關文章！
