Return value from BukkitRunnable

Question

I add values to a map async using a BukkitRunnable and then I want to return the map.

    public Map<String, Object> test() {
    final Map<String, Object> testMap = new HashMap<>();

    new BukkitRunnable() {
        @Override
        public void run() {
            testMap.put("A", 1);
            testMap.put("B", 2);
        }
    }.runTaskAsynchronously(bridge);

    return testMap;
}

If I want to use this map it will always be empty. It is returned before the values are added to the map since I'm adding them in another thread.

I really want to use a BukkitRunnable and not a Future. How can I accomplish that? I'd need to return the map with a delay or, better, return the map, somehow, from the BukkitRunnable.

Answer 1

The problem is that the Map will be returned directly but the task will run async so you will get an empty Map returned. So you should add a Consumer to the method to get the async result.

Try this:

public void test(Consumer<Map<String, Object>> callback) {
    final Map<String, Object> yourMap = new HashMap<>();
    new BukkitRunnable() {
        @Override
        public void run() {
            yourMap.put("A", something);
            yourMap.put("B", 1.5);
            callback.accept(yourMap); //here the consumer gets the map
        }
    }.runTaskAsynchronously(bridge);
}

Usage lambda:

...
referenceToClass.test(map -> { //Lambda
    Object someObject = map.get("A"); 
});

Usage normal:

...
referenceToClass.test(new Consumer<Map<String, Object>() {
    @Override
    public void accept(Map<String, Object> map) {
        Object someObject = map.get("A"); 
    }
});