Java线程 - 工作线程改变其老板的hashmap

Question

I have a class (Server) which listens for requests and once a request is made, starts a new thread which handles it. The handler thread will read in the data, store it into a hashmap and finish. I have put the hashmap in the server class as there can be multiple handler threads reading in the data as and when it comes in.

I'm confused whether this is the correct approach as in order to alter/access the hashmap, I'd have to write getters & setters and pass in the Server class to each and every worker thread. Some example code to try and describe my query:

public class Server implements Runnable {
        private HashMap<String, Integer> data;

    public void run() {
       while(true) {
            Socket s = serverSocket.accept();
            Handler h = new Handler(s);
            Thread t = new Thread(h);
            t.start();
       }
   }
}

public class Handler implements Runnable {

    public void run() {
        //read in data from socket
        data.put(d); //access the hashmap and insert data in
    } 

}

Any advice would be much appreciated. Thanks.

Answer 1

Your approach is fine, but you should either use a ConcurrentMap , or synchronize on the map. The first approach is better since synchronized collections are optimized in order to avoid blocking whenever it is possible.