concurrenthashmap « Thread Safe « Java Thread Q&A

1. Java ConcurrentHashMap not thread safe.. wth?    stackoverflow.com

I was using HashMap before like

   public Map<SocketChannel, UserProfile> clients = new HashMap<SocketChannel, UserProfile>();

2. Is read/writing from/in ConcurrentHashMap in ConcurrentHashMap thread safe?    coderanch.com

Each map is synchronized separately, and the method calls you show are not different than handling the calls on different lines: String value = a.get("key1").get("key2"); /* is equivalant to */ Map b = a.get("key1"); String value = b.get("key2"); So getting the Map from a is thread safe in that a will not be modified while the get() occurs. Similarly getting the ...