来自整数流的双重数组答案

【问题标题】：doubly array from a stream of integers来自整数流的双重数组
【发布时间】：2021-03-22 09:53:36
【问题描述】：

如何将 Flux 转换为 Flux.

我有一个 Flux -> {1,2,3,.....100} 我想按 30 个数字对它们进行分组 -> [[1,2,3,.....30 ], [31,32....60],[61.....100]]

我尝试了以下方法，但没有成功。元素被分组为 5 [ [1,2,3,4,5], [6,7,8,9,10],.....]

Flux<int[][]> groupedData = fluxData.map(x -> {
            int outerArraySize = (int) Math.ceil(x.size() / 30) +1;
            System.out.println(outerArraySize);

            int[][] boxedData = new int[30][outerArraySize];
            AtomicInteger innerArray = new AtomicInteger(0);
            AtomicInteger outerArray = new AtomicInteger(0);

            x.forEach(ids -> {

                boxedData[innerArray.get()][outerArray.get()] = ids;
                innerArray.getAndIncrement();
                if (innerArray.get() == 30) {
                    innerArray.set(0);
                    outerArray.getAndIncrement();
                }


            });

【问题讨论】：

什么是Flux？ Flux 的map 方法有什么作用？

标签： spring-boot java-8 java-stream reactive-streams

【解决方案1】：

Flux 有一个有用的操作符叫做 'buffer'，我们可以用它来批处理整数列表。

我已经像这样创建了我的“fluxData”，只是为了测试我的代码：

    List<Integer> list1 = IntStream.rangeClosed(1, 100).boxed().collect(Collectors.toList());
    List<Integer> list2 = IntStream.rangeClosed(1, 40).boxed().collect(Collectors.toList());
    List<Integer> list3 = IntStream.rangeClosed(1, 70).boxed().collect(Collectors.toList());

    Flux<List<Integer>> fluxData = Flux.just(list1, list2, list3);

现在，我们可以执行以下操作：

    fluxData.map(integersList -> {
                List<List<Integer>> batchesList = Flux.fromStream(integersList.stream())
                        .buffer(30) // This the magic.
                        .collectList()
                        .block();

                // List<List<Integer>> --> int[][]
                int[][] batchesArray = new int[batchesList.size()][];
                for(int i = 0;i < batchesArray.length;i++){
                    batchesArray[i] = new int[batchesList.get(i).size()];
                    for (int j = 0; j < batchesArray[i].length; j++) {
                        batchesArray[i][j] = batchesList.get(i).get(j);
                    }
                }

                return batchesArray;
            })
            .subscribe(batchesArray -> System.out.println(Arrays.deepToString(batchesArray)));

输出：

[[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30], [31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60], [61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90], [91, 92, 93, 94, 95, 96, 97, 98, 99, 100]]
[[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30], [31, 32, 33, 34, 35, 36, 37, 38, 39, 40]]
[[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30], [31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60], [61, 62, 63, 64, 65, 66, 67, 68, 69, 70]]

【讨论】：