I have create a Class OrderFetcher that implements Callable interface returns a Integer from Call Method as below

public class OrderFetcher implements Callable<Integer> {
    @Override
    public Integer call() throws Exception {
        sleep(200);
        Random random = new Random();
        return random.nextInt(10);
    }
}

I have also created another two classes InventoryFetcher & PaymentFetcher and these also implements callable interface

public class InventoryFetcher implements Callable {

public InventoryFetcher(Integer orderId) {
    this.orderId = orderId;
}

Integer orderId;

@Override
public Boolean call() throws Exception {
    sleep(200);
    return this.orderId%2==0?true:false;
}

}

public class PaymentFetcher implements Callable {

Boolean flag;

public PaymentFetcher(Boolean flag) {
    this.flag = flag;
}

@Override
public String call() throws Exception {
    sleep(200);
    return flag?"Payment Accepted":"Payment Rejected";
}

}

I tried them with Futures and it works well where i am calling the OrderFetcher to return a value and pass that in InventoryFethcer and the pass the output from InventoryFetcher to PaymnetFethcer class. Ones output is Input to other and so on.

But how can i acheve this in CompletableFuture? It asking for a supplier interface implementation