[Java知识库]java 流处理demo记录

 @Test
    public void testStream(){
        Object lock = new Object();

        ArrayList<Integer> collect = Arrays.asList(1, 2, 3, 4, 5)
                .parallelStream()  //并行流
                .collect(() -> {  //构造器参数
                    synchronized (lock) {  //加锁是为了并行流下方便查看打印结果
                        System.out.println("constructor:Thread:" + Thread.currentThread());
                        System.out.println();  //为了换行方便查看打印
                        return new ArrayList<Integer>();
                    }
                }, (a, b) -> {  //累加参数
                    synchronized (lock) {  //加锁是为了并行流下方便查看打印结果
                        System.out.println("accumulator:Thread:" + Thread.currentThread());
                        System.out.println("a:" + a);
                        System.out.println("b:" + b);
                        System.out.println();  //为了换行方便查看打印
                        a.add(b);
                    }
                }, (a, b) -> {  //合并参数
                    synchronized (lock) {  //加锁是为了并行流下方便查看打印结果
                        System.out.println("combiner->a:length:" + a.size() + " " + "b:length:" + b.size());
                        System.out.println("a:" + a + ",b:" + b);
                        a.addAll(b);
                        System.out.println();  //为了换行方便查看打印
                    }
                });
        //.forEach(item -> System.out.println("Thread:" + Thread.currentThread() + " All:" + item));
        System.out.println("all:"+collect);

    }