CompletableFuture

港控/mmm° 2022-10-05 10:59 150阅读 0赞

import com.google.common.collect.Lists;
    import java.util.List;
    import java.util.concurrent.CompletableFuture;
    import java.util.concurrent.ExecutionException;
    import java.util.concurrent.ExecutorService;
    import java.util.concurrent.Executors;
    import java.util.concurrent.TimeUnit;
    import java.util.concurrent.TimeoutException;
    import java.util.concurrent.atomic.AtomicInteger;
    
    
    public class Test {
        public static void main(String[] args) throws InterruptedException, ExecutionException, TimeoutException {
    //        test();
    //        System.out.println("___________________________________");
    //        completableTest();
    //        testGet();
            testJoin();
        }
    
        public static void testJoin(){
            CompletableFuture<Integer> f1 = CompletableFuture.supplyAsync(() -> {
                int i =1/0;
                return 1;
            });
            CompletableFuture.allOf(f1).join();
            System.out.println("CompletableFuture Test");
    
        }
    
        public static void testGet() throws ExecutionException, InterruptedException {
            CompletableFuture<Integer> f1 = CompletableFuture.supplyAsync(() -> {
                int i =1/0;
                return 1;
            });
            f1.get();
            System.out.println("CompletableFuture Test");
        }
    
        private static void test() {
            Long t1 = System.currentTimeMillis();
            int sum = 0;
            for (int i = 0; i < 10; i++) {
                int t = 0;
                for (int j = 0; j < 2000000000; j++) {
                    t++;
                }
                sum += t;
            }
            System.out.println(sum);
            System.out.println(System.currentTimeMillis() - t1);
        }
    
        private static void completableTest() throws InterruptedException, ExecutionException, TimeoutException {
            Long t1 = System.currentTimeMillis();
            ExecutorService executorService = Executors.newFixedThreadPool(20);
    
            List<CompletableFuture<Void>> futureList = Lists.newArrayList();
            AtomicInteger sum = new AtomicInteger();
            for (int i = 0; i < 10; i++) {
                CompletableFuture<Void> future = CompletableFuture.runAsync(() -> {
                    int t = 0;
                    for (int j = 0; j < 2000000000; j++) {
                        t++;
                    }
                    sum.addAndGet(t);
                }, executorService);
                futureList.add(future);
            }
    //        CompletableFuture<Void> combineFuture = CompletableFuture.allOf(futureList.toArray(new CompletableFuture[0]));
    //        combineFuture.join();
            CompletableFuture.allOf(futureList.toArray(new CompletableFuture[0])).get(1000L, TimeUnit.SECONDS);
            System.out.println(sum);
            System.out.println(System.currentTimeMillis() - t1);
        }
    }