老有同事问我写写统计图标的问题，例如按照日期范围每日的数据信息展示，我就写个例子放在这里，再问打死。
public class ResultVo {
public static void main(String[] args) {
LocalDate startDate = LocalDate.of (2021,2,1);
LocalDate endDate = LocalDate.of (2021,3,1);
List<TestData> formDbList= new ArrayList<TestData>(){{
add(TestData.builder().dateStr("20210202").otherData("A").build());
add(TestData.builder().dateStr("20210214").otherData("B").build());
add(TestData.builder().dateStr("20210301").otherData("C").build());
}};
long apart = ChronoUnit.DAYS.between(startDate, endDate);
List<TestData> newData = new ArrayList<>();
if (dex > 0) {
Stream.iterate(startDate, d -> d.plusDays(1)).limit(apart + 1).forEach(f -> {
String dateKey= f.format(DateTimeFormatter.ofPattern("yyyyMMdd"));
Optional<TestData> dbData = formDbList.stream().filter(fdl -> dateKey.equals(fdl.dateStr)).findFirst();
if (dbData.isPresent()) {
newData.add(dbData.get());
return;
}
newData.add(TestData.builder().dateStr(dateKey).otherData("没有数据").build());
});
}
newData.sort((a,b)-> {
if (Integer.parseInt(a.dateStr)>Integer.parseInt(b.dateStr)) {
return 1;
}else{
return -1;
}
});
System.out.println(newData);
}
@Data
@Builder
public static class TestData {
private String dateStr;
private String otherData;
}
}