Java8分组要映射的列表列表列表
2023-09-07 02:00:16
作者：庸俗且孤独
我有一个 Model 和一个具有以下签名的 Property 类:
I have a Model and a Property class with the following signatures:
public class Property {
public String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
public class Model {
private List<Property> properties = new ArrayList<>();
public List<Property> getProperties() {
return properties;
}
}
我想要 List<Model> 中的 Map<String, Set<Model>>，其中键是 Property类.如何使用 java8 流按其 Properyes 名称对该列表进行分组?所有 Property 的名称都是唯一的.
I want a Map<String, Set<Model>> from a List<Model> where the key would be the name from the Property class. How can I can I use java8 streams to group that list by its Properyes' name? All Propertyes are unique by name.
可以在单个流中解决，还是应该以某种方式拆分它还是采用经典解决方案?
It is possible to solve in a single stream or should I split it somehow or go for the classical solution?
推荐答案
yourModels.stream()
.flatMap(model -> model.getProperties().stream()
.map(property -> new AbstractMap.SimpleEntry<>(model, property.getName())))
.collect(Collectors.groupingBy(
Entry::getValue,
Collectors.mapping(
Entry::getKey,
Collectors.toSet())));
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