Is this null pointer exception in TreeMap due to concurrent access?
问题 I know that TreeMap is not thread safe. I am trying to do a comparison of TreeMap with ConcurrentSkipListMap. Code I use is shown below and I want to make sure if the error I am getting is due TreeMap not being threadsafe and not because of some other. Exception in thread "pool-1-thread-52" java.lang.NullPointerException at java.util.TreeMap.rotateLeft(TreeMap.java:2060) at java.util.TreeMap.fixAfterInsertion(TreeMap.java:2127) at java.util.TreeMap.put(TreeMap.java:574) at ThreadTestTreeMap$1