자바 Callback

package main.java.com;

public class CallbackMain {
    public static void main(String args[]) {
        System.out.println("start");

        MyCallback callback = new MyCallback();

        //성공 케이스.
        callback.doWork("4", "7");

        //실패 케이스.
        callback.doWork("4", "&");

        callback.finish();

        System.out.println("end");
    }
}

 

package main.java.com;

import java.nio.channels.CompletionHandler;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class MyCallback {
    private ExecutorService executorService;

    public MyCallback(){
        this.executorService = Executors.newCachedThreadPool();
    }

    private CompletionHandler<Integer, Void> callback = new CompletionHandler<Integer, Void>() {
        @Override
        public void completed(Integer result, Void attachment) {
            System.out.println("Completed");
        }

        @Override
        public void failed(Throwable exc, Void attachment) {
            System.out.println("Failed");
        }
    };

    public void doWork(final String x, final String y){
        Runnable task = new Runnable() {
            @Override
            public void run() {
                try{
                    int result = Integer.parseInt(x) + Integer.parseInt(y);

                    callback.completed(result, null);
                }catch (Exception ex){
                    callback.failed(ex,null);
                }
            }
        };

        executorService.submit(task);
    }

    public void finish(){
        executorService.shutdown();
    }
}