在我的Java项目中,我需要以多种方式使用TreeMap.我发现ConcurrentSkipListMap是我需要的,但是有些方法不是线程安全的.其中之一-containsKey(Object key).以多种方式使用此方法的典型解决方案是什么？在我的程序中,我需要放置不会替换旧密钥的密钥,如果不可能的话,我将放置另一个密钥而不会获得唯一密钥.因为我不会丢失信息,所以应该使用哪种结构来代替containsKey？

解决方法:

如果您担心containsKey结果会过时,然后再对其执行操作,或者大约this warning in the javadoc：

Additionally, the bulk operations putAll, equals, toArray, containsValue, and clear are not guaranteed to be performed atomically. For example, an iterator operating concurrently with a putAll operation might view only some of the added elements.

在ConcurrentSkipListMap上定义了一些方法,您可以改用这些方法.例如,请参见putIfAbsent：

If the specified key is not already associated with a value, associate it with the given value. This is equivalent to

if (!map.containsKey(key))
    return map.put(key, value);
else
    return map.get(key);

except that the action is performed atomically.

另请参阅删除和替换方法.