How can I represent key with list of values for each environment type in an Enum?

Question

I have two environment PROD and STAGING. In prod environment we have three datacenters ABC, DEF and PQR and stag

Answer 1

While this is a bit tricky without knowing full implementation I might be able to get you started.

Enums are interesting in that they are Immutable which solves the declaring constant fields and variables. Here is my attempt to solve what you are looking for.

public enum Server {
    // Constant style naming because Enums are Immutable objects
    ABC_SERVERS("tcp://machineA:8081", "tcp://machineA:8082"),
    DEF_SERVERS("tcp://machineB:8081", "tcp://machineB:8082"),
    PQR_SERVERS("tcp://machineC:8081", "tcp://machineC:8082"),
    CORP("tcp://machineZ:8081");

    /* After the name declaration you can essentially do normal class 
       development
    */ Fields
    private List servers = new ArrayList<>();
    public boolean isProd; // you could use something as simple as a 
    //boolean to determine the environment

    // Enums use a private constructor because they are never 
    //instantiated outside of creation of this Enum class
    private Server(String... dataCenter){

    // because of the varargs parameter there is a potential for 
    //multiple Strings to be passed
        for (String tcp :
                dataCenter) {
            this.servers.add(tcp);
        }

        // You can access the name property of the Enum that is being created
        if (this.name() == "CORP")
            this.isProd = false;
        else
            this.isProd = true;

    }

    // You could make the List public but this demonstrates some encapsulation
    public List getServers() {
        return servers;
    }
}

I then checked that each "machine" was being added in another class

    // these are what I used to check to make sure that each string is being "mapped" correctly
    List prodServer = new ArrayList<>();
    List stagingServer = new ArrayList<>();

    for (Server server :
            Server.values()) {
        if (server.isProd) {
            for (String machine :
                    server.getServers()) {
                prodServer.add(machine);
            }
        }
        else {
            for (String machine:
                    server.getServers()) {
                stagingServer.add(machine);
            }
        }
    }

    System.out.println(prodServer);

    System.out.println(stagingServer);

Also note that to get the actual enum names you use the .values() function of the Enum class.