使用流将一个类对象转换为另一个类对象 [英] convert one class object into another using stream
问题描述
我知道这个问题可能会引起误解，如果可能有人可以纠正它，我不确定在这种情况下如何提出问题.
I know this question can be misleading, if possible someone may correct it, I am not sure how to ask a question with this situation.
我正在尝试将X类转换为Y类(此处Y类包含X类的字段，但是以不同的方式，例如:X类内部的 Integer a, b;，在Y类中转换为Map<a, b> ，而其他变量保持不变.)，
I am trying to Convert Class X into Class Y (here class Y contains fields of class X, but in different way, Eg:- Integer a, b; inside class X , converts to Map<a, b> in class Y while other variables stay the same.),
在Java 8中使用流. 我正在尝试将最终对象作为json返回到UI 部分. 该项目在 spring boot 中完成. X类和Y类都包含相同的对象，但是Y类是使X类与众不同 我对流不熟悉.
using streams in java 8. I am trying to return the final object to the UI part as json. The project is done in spring boot. Both Class X and Y contains the same objects, but Class Y is to make class X distinct I am not familiar with streams.
X类
public class X {
private final String thumbnailUrl;
private final Integer duration;
private final String contentId;
private final Date reportDate;
private final Integer count;
public X(Report report, int count) {
this.thumbnailUrl = report.getContent().getThumbnailUrl();
this.duration = report.getContent().getDuration();
this.contentId = report.getContent().getContentId();
this.reportDate = report.getReportDate();
this.count = count;
}
public String getThumbnailUrl() {
return thumbnailUrl;
}
public Integer getDuration() {
return duration;
}
public String getContentId() {
return contentId;
}
public Date getReportDate() {
return reportDate;
}
public Integer getCount() {
return count;
}
}
Y类
public class Y {
private final String thumbnailUrl;
private final Integer duration;
private final String contentId;
private final Map<Date, Integer> contentList;
public Y(X x, Map<Date, Integer> contentList) {
this.thumbnailUrl = x.getThumbnailUrl();
this.duration = x.getDuration();
this.contentId = x.getContentId();
this.contentList = contentList;
}
public String getThumbnailUrl() {
return thumbnailUrl;
}
public Integer getDuration() {
return duration;
}
public String getContentId() {
return contentId;
}
public Map<Date, Integer> getContentList() {
return contentList;
}
}
这是我目前从X班获得的
This is what I am currently getting from class X
[
{
"thumbnailUrl": "a",
"duration": 12,
"contentId": "CNT10",
"reportDate": "2020-01-20",
"count": 3
},
{
"thumbnailUrl": "a",
"duration": 12,
"contentId": "CNT10",
"reportDate": "2020-01-21",
"count": 5
},
{
"thumbnailUrl": "a",
"duration": 12,
"contentId": "CNT10",
"reportDate": "2020-01-22",
"count": 3
},
{
"thumbnailUrl": "a",
"duration": 12,
"contentId": "CNT10",
"reportDate": "2020-01-23",
"count": 4
}
]
使用此代码并返回最终列表后，我在邮递员中得到了上述json.
I got the above json in postman after using this code and returning the final list.
List<X> x;
List<Y> y;
x = StreamSupport.stream(reportRepository
.reportWithRoll(a, b, c).spliterator(), false)
.map(report -> new X(report, report.getStartCount()))
.collect(Collectors.toList());
我希望将其转换为如下所示的Y类内容. 如何使用Java流实现此目标?
I want this to transformed into content of Class Y as below. How can I achieve this with streams in Java?
[
{
"list": [
{
"2020-01-20": 3,
"2020-01-21": 5,
"2020-01-22": 3,
"2020-01-23": 4
}
],
"thumbnailUrl": "a",
"duration": 12,
"contentId": "CNT10"
}
]
我尝试使用此方法获取上述json格式，但最终获得了重复的数据(单个contentId重复)和多个contentId错误
I tried this to get the above json format, but ended up getting duplicate data, for single contentId and error for multiple contentId
y = x.stream().map(
rep -> {
Map<Date, Integer> contentList = x.stream().collect(
Collectors.toMap(X::getReportDate, X::getCount)
);
Y yy = new Y(rep, contentList);
return yy;
}
).distinct().collect(Collectors.toList());
我将常见的日期和计数:键值对组合为每个唯一的"contentId"的单个列表"(每个唯一的"contentId"都有其专用的"thumbnailUrl"和"duration"，所以当我指的是"contentId"是唯一的，它将包括"thumbnailUrl"和"duration"，其中每个的日期和计数都将是多个.)
I am combining the common date and count : key value pair into a single "list" for each unique "contentId" (each unique "contentId" will have its own "thumbnailUrl" and "duration" specific to it, so when I am referring only "contentId" as unique, it will include "thumbnailUrl" and "duration", only the date and count will be multiple for each of these).
推荐答案
由于堆栈溢出我得到了以下json
I got the following json with this
[
{
"thumbnailUrl": "a",
"duration": 12,
"contentId": "CNT10",
"contentList": {
"2020-01-21T18:30:00.000+0000": 3,
"2020-01-20T18:30:00.000+0000": 3,
"2020-01-22T18:30:00.000+0000": 3,
"2020-01-19T18:30:00.000+0000": 3
}
},
{
"thumbnailUrl": "b",
"duration": 12,
"contentId": "CNT12",
"contentList": {
"2020-01-19T18:30:00.000+0000": 3
}
},
{
"thumbnailUrl": "c",
"duration": 12,
"contentId": "CNT11",
"contentList": {
"2020-01-21T18:30:00.000+0000": 3,
"2020-01-20T18:30:00.000+0000": 3,
"2020-01-19T18:30:00.000+0000": 3
}
}
]
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