https://twitter.com/karupanerura/status/552026018412630017

AsyncExample.java

public class AsyncExample {
    public void run () {
        Client client = new Client();
        Listener listener = new Listener () {
            @Override
            public void onSuccess (Result result) {
                ...;
            }
        };
        
        client.request("SELECT * FROM foo WHERE id = 1", listener);
    }
}

Client.java

public class Client {
    ...    

    public void request (String query, Listener listener) {
        queue.add(query, listener); // ここにつっこむとWorker Threadがよしなに処理してlistener.onSuccess()を呼び出してくれる的なやつ
    }
}

Listener.java

public abstract class Listener {
    public abstract void onSuccess (Result result);
}

ListenerFuture.java

import java.util.concurrent.Future;

public class ListenerFuture extends Listener implements Future<Result> {
    private Result result;    

    public Result get() {
        ...; // 実行が終わるまで待つ処理
        return result;
    }
    
    ...

    @Override
    public void onSuccess (Result result) {
        this.result = result;
    }
}

SyncExample.java

public class SyncExample {
    public void run () {
        Client client = new Client();
        ListenerFuture listener = new ListenerFuture();
        
        client.request("SELECT * FROM foo WHERE id = 1", listener);
        Result result = listener.get();
        ...;
    }
}