Java - Future

import java.time.LocalTime;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;


public class JavaFuture1
{
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        //ExecutorService 초기화
        ExecutorService executor = Executors.newSingleThreadExecutor();

        //Callable Task 생성
        Callable<String> callableTask = () -> {
            System.out.println(LocalTime.now() + " Task Start");
            Thread.sleep(1000L);
            return "Task Result";
        };

        //submit() 메서드로 Task 실행
        Future<String> future = executor.submit(callableTask);

        System.out.println(LocalTime.now() + " Waiting the task done");
        System.out.println("isDone 1 = " + future.isDone());
        String result = future.get();  //Task 결과 대기
        System.out.println("isDone 2 = " + future.isDone());
        System.out.println(LocalTime.now() + " future.get() = " + result);
    }
}

 

import java.time.LocalTime;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

public class JavaFuture2 {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        ExecutorService executor = Executors.newSingleThreadExecutor();

        Callable<String> callableTask = () -> {
            System.out.println(LocalTime.now() + " Task Start");
            Thread.sleep(2000L);
            System.out.println(LocalTime.now() + " Task End");
            return "Task Result";
        };

        Future<String> future = executor.submit(callableTask);

        System.out.println(LocalTime.now() + " Waiting the task done");
        String result = null;
        try {
            result = future.get(1000, TimeUnit.MILLISECONDS);
        } catch (TimeoutException e) {
            System.out.println(LocalTime.now() + " TimeoutException 발생");
        }
        System.out.println(LocalTime.now() + " future.get() = " + result);
    }	
}

 

 

import java.time.LocalTime;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

public class JavaFuture3 {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        ExecutorService executor = Executors.newSingleThreadExecutor();

        Callable<String> callableTask = () -> {
            System.out.println(LocalTime.now() + " Task Start");
            Thread.sleep(2000L);
            return "Task Result";
        };

        Future<String> future = executor.submit(callableTask);
        Thread.sleep(1000L);
        boolean cancelResult = future.cancel(true);
        System.out.println("cancelResult = " + cancelResult);
        System.out.println("isCancelled = " + future.isCancelled());

        String result = future.get();  //Task 결과 대기
        System.out.println(LocalTime.now() + " future.get() = " + result);
    }
}

 

 

https://wildeveloperetrain.tistory.com/141

Java - Future Interface 비동기적 연산 작업을 위한 인터페이스