Question

I have a client-server architecture where there is a client connected to a Central Server and then I have this central Server connected to two Servers (Server1 and Server2). I pass a Map Object from the client to the CentralServer using the Serializable class. Then, in the CentralServer I want to get this Map Object and get the Key and the value from them. For that I am using the following code:

public void readObject(Map<String, byte[]> parObj)
{   
    for (String key : keys) 
    {
        if(parObj.containsKey(key) == true){
            foundAnyKey = true;
            byte[] values = parObj.get(key);
            //Do Something here
       }
   }
     if(foundAnyKey == true){
            //Do something here
     }
}

Correct me if I’m wrong. Am I doing this first part of getting the key and the value right?

The second part of my question is How can I send the keys that for instance begin with “a-f” to the Server1 and the keys that begin in “f-z” to the Server2. How can I do that?

In my main I have the following code:

System.out.println("Starting Server");
        ServerSocket ss = new ServerSocket(7776);  
        System.out.println("Server Started"); 
        Socket s = ss.accept();
        InputStream is = s.getInputStream();                    
        ObjectInputStream ois = new ObjectInputStream(is);      
        MapObject mo = (MapObject) ois.readObject();
        s.close();

This is where I get my MapObject form the client. Now I want to get the key and the value from this object.
Best regards

Answer 1

If you question is about an “ordered” map then you take a look to LinkedHashMap (if you care about insertion order) or a TreeMap (where you define a compareTo() method to have a sorting rule).
Then you can loop the keys simply with the method

Set keys = map.keySet();

And then you can iterate over the (previously ordered) Set of keys.