Question

I do have access to few Servers say A, B, C, D and E. I’d like to choose data from these servers one by one in a round robin way. I am new to Java and threads, It would be a great help if you could help me with this.

What I am trying to do is to load a map in my application, I send HTTP requests to the servers. These Servers revert response in Bitmap format, I arrange these Images (Tiles) and show it in my application, but I am doing it it sequentially. E.g. I request Server A first to get the tiles then Server B and so on..I would like to get the tiles in such a way that Server A downloads one Image, Server B does the other. If I if I’d be doing it all alone using one server without using Multithreading it would take a long time to display whole Map.

Answer 1

use modulo see example:
(used String as the url)

public static final int MAX_SERVER = 4;

public static void main(String[] args)
{

    String urlarr[] = new String[MAX_SERVER];
    init(urlarr);

    int idx = 0;
    while(idx < 1000){
        String next = urlarr[idx++%urlarr.length];
        System.out.println(next);
    }
}

private static void init(String[] urlarr)
{
    for(int i=0 ; i<urlarr.length ; i++){
        urlarr[i] = "url("+i+")";
    }

}

using module size of array on idx make it iterates over all available indexes 0,1,2,3 in this case.
part of output:

url(0)
url(1)
url(2)
url(3)
url(0)
url(1)
url(2)
url(3)