java lambda 实际使用总结

墨蓝 2022-05-08 07:58 225阅读 0赞

1、获取列表中的某一列形成新的列表。

List<ProjectWithEpic> projectWithEpics = (List<ProjectWithEpic>) limitprojectWithEpics.getList();
            List list1 = new ArrayList();
            projectWithEpics.forEach(n -> list1.add(n.getEpicid()));

2、获取列表中某一列的和

获取列表中符合某个条件的某一列的和

列表中符合某个条件的形成新的列

List<IssueStatusWithPoints> pointsTwo = projectCategoryMapper.getPointsFromChildEpic(Integer.parseInt(epicid));
                        if (pointsTwo.size() > 0) {
                            sum2 = pointsTwo.stream().mapToInt(t -> t.getPoints()).sum();
                            sumdone2 = pointsTwo.stream().filter(t -> t.getIssuestatus() == 10001).mapToInt(t -> t.getPoints()).sum();
                            sumundone2 = sum2 - sumdone2;
                            if (sumundone2 > 0) {
                                List<IssueStatusWithPoints> list3 = pointsTwo.stream().filter(t -> t.getIssuestatus() != 10001).collect(Collectors.toList());
                                List list4 = new ArrayList();
                                list3.forEach(m -> list4.add(m.getId()));
                                Map map = new HashMap();
                                map.put("list", list4);
                                List<IssueStatusWithPoints> undopointsWithSprint2 = projectCategoryMapper.getUndopointsWithSprint2(map);
                                if (undopointsWithSprint2.size() > 0) {
                                    undopointswithsprint2 = undopointsWithSprint2.stream().mapToInt(n -> n.getPoints()).sum();
                                    undopointswithbacklog2 = sumundone2 - undopointswithsprint2;
                                } else {
                                    undopointswithsprint2 = 0;
                                    undopointswithbacklog2 = sumundone2 - undopointswithsprint2;
                                }
                            }