java中线程安全的集合

一、CopyOnWriteArrayList

迭代的同时进行修改会发生ConcurrentModificationException异常，推荐使用CopyOnWriteArrayList

List<RtuTagAct> rtuTagActList = entry.getValue();
for (RtuTagAct rtuTagAct:rtuTagActList) {
     if (rtuTagAct.getTagKey().equals(pushKey)) {
         rtuTagActList.remove(rtuTagAct);
                }
            }

下面是修改后的实现

List<RtuTagAct> rtuTagActList0 = entry.getValue();
List<RtuTagAct> rtuTagActList = new CopyOnWriteArrayList<>(rtuTagActList0);
for (RtuTagAct rtuTagAct:rtuTagActList) {
    if (rtuTagAct.getTagKey().equals(pushKey)) {
        rtuTagActList.remove(rtuTagAct);
                }
            }

二、ConcurrentHashMap

并发时修改Map,推荐使用ConcurrentHashMap，不然可能发生不可预料的后果

比如如下实现，算出的数据根本就是错误的

Map<String, Double> result = new HashMap<>();
atIdList.forEach(meterId -> {
            Double now = rtValueMap.get(meterId); 
            Double node = hiveRTValueMap.get(meterId);
            double todayValue = ArithUtils.sub(now, node);
             result.put(meterId, todayValue);  
            }
        });

采用如下修改后的代码，果然就没问题了

Map<String, Double> result = new ConcurrentHashMap<>();
atIdList.forEach(meterId -> {
            Double now = rtValueMap.get(meterId); 
            Double node = hiveRTValueMap.get(meterId);
            double todayValue = ArithUtils.sub(now, node);
             result.put(meterId, todayValue);  
            }
        });

三、 其他

interface	non-thread-safe	thread-safe
List	ArrayList	CopyOnWriteArrayList
Map	HashMap	ConcurrentHashMap
Set	HashSet / TreeSet	CopyOnWriteArraySet
Queue	ArrayDeque / LinkedList	ArrayBlockingQueue / LinkedBlockingQueue
Deque	ArrayDeque / LinkedList	LinkedBlockingDeque