stream 流计算和for计算

  /**
     * 普通方法
     * 执行时间 730
     */
    @Test
    public void test1() {
        long start = System.currentTimeMillis();
        long  sum =0;
        for (long i = 1L; i <= 1000000000L; i++) {
            sum+=i;
        }
        System.out.println(sum);
        long end = System.currentTimeMillis();
        System.out.println(end-start);
    }

    /**
     * stream 并行流
     *  执行时间 484
     */
    @Test
    public void test2() {
        long start = System.currentTimeMillis();
        long sum = LongStream.rangeClosed(0L, 1000000000L).parallel().reduce(0L, Long::sum);
        System.out.println(sum);
        long end = System.currentTimeMillis();
        System.out.println(end-start);
    }