AutoReconnect with multiple server uri's - paho

Question

Consider the scenario where I have below code.
MqttConnectOptions connOpt = new MqttConnectOptions();
connOpt.setServerURIs(new String[]{"tcp://localhost:1883", "tcp://some-other-host:1883"});
connOpt.setAutomaticReconnect(true);
client.setCallback( new TemperatureSubscriber() );
client.connect(connOpt);
So when I say connect, it connects to localhost.
Then I get connection lost, due to say any reason. So at this point of time, since automaticReconnect is true, will it connect to localhost or some-other-host ?

Answer 1

Let me show how to find such answers yourself -
First you visit the Github repository for Paho source code.
Then you enter setAutomaticReconnect into the search field:
This is of course just the public name. You need to spot the corresponding private member.
In the MqttConnectOptions.java with the very simple code you find that member:
private boolean automaticReconnect = false;
Then you perform another search, this time for the automaticReconnect word:
And that leads you to the hint in the MqttAsyncClient.java file -
// Insert our own callback to iterate through the URIs till the connect
// succeeds
MqttToken userToken = new MqttToken(getClientId());
ConnectActionListener connectActionListener = new ConnectActionListener(this, persistence, comms, options,
userToken, userContext, callback, reconnecting);
userToken.setActionCallback(connectActionListener);
userToken.setUserContext(this);
Finally, in the ConnectActionListener.java file you can confirm that the URLs are being tried one after each other:
/**
* The connect failed, so try the next URI on the list.
* If there are no more URIs, then fail the overall connect.
*
* #param token the {#link IMqttToken} from the failed connection attempt
* #param exception the {#link Throwable} exception from the failed connection attempt
*/
public void onFailure(IMqttToken token, Throwable exception) {
int numberOfURIs = comms.getNetworkModules().length;
int index = comms.getNetworkModuleIndex();
...
...
comms.setNetworkModuleIndex(index + 1);