Question

以下是场景：

我有一个Segment对象列表：我需要按照组进行分组的列表段。

**细分数据**

[CODE]: 9X-594 (D/ET) - [SET]: 1
[CODE]: 9X-600 (D/ET) - [SET]: 2
[CODE]: 9X-602 (D/ET) - [SET]: 3
[CODE]: 9X-596 (D/ET) - [SET]: 4

[CODE]: 9X-970 (S/ET) - [SET]: 5
[CODE]: 9X-579 (E/ET)

[CODE]: 9X-974 (S/ET) - [SET]: 6
[CODE]: 9X-589 (E/ET)
[CODE]: 9X-599 (E/ET)

[CODE]: 9X-964 (S/ET) - [SET]: 7
[CODE]: 9X-581 (E/ET)

我需要将这些数据分组为以下格式：

List<CodeSample> samples = new ArrayList<CodeSample>();

其中CodeSample是包含Segment列表的类。

public class CodeSample {

    private int set;
    private List<Segment> segments;

    //getters/setters here
    ...
}

我需要按集合对细分进行分组，例如：

samples = [
    { set: 1, [{code: "9x-594 (D/ET)"}]},
    { set: 2, [{code: "9x-600 (D/ET)"}]},
    { set: 3, [{code: "9x-602 (D/ET)"}]},
    { set: 4, [{code: "9x-596 (D/ET)"}]},
    { set: 5, [{code: "9x-970 (D/ET)"}, {code: "9x-579 (D/ET)"}]},
    { set: 6, [{code: "9x-974 (D/ET)"}, {code: "9x-589 (D/ET)"}, {code: "9x-599 (D/ET)"}]},
    { set: 7, [{code: "9x-964 (D/ET)"}, {code: "9x-581 (D/ET)"}]}
]

我需要创建一个包含段列表（已分组）的样本列表。

此方案的最佳方法是什么？

Answer 1

List<CodeSample> result = 
    segments.stream()
            .collect(Collectors.groupingBy(Segment::getSet))
            .entrySet()
            .stream()
            .map(entry -> new CodeSample(entry.getKey(), entry.getValue()))
            .collect(Collectors.toList());

Java：如何按属性对列表元素进行分组

1 个答案: