如何基于嵌套对象属性对列表进行排序 [英] How to sort list based on nested object property

问题描述

我是Java流的新手，我只想对对象的键进行排序.

I am new to Java streams and I just want to sort the keys for my object.

所以，我尝试这样的方法，它能起作用

So, I try something like this and it works

List<FooSelect> li= Arrays.stream(obj.getFoos().getFoo())  //Stream<Foo>
    .map(Foo::getSelect)                                   //Stream<FooSelect>
    .sorted(Comparator.comparing(FooSelect::getFoosKey))   //Stream<FooSelect>
    .collect(Collectors.toList());

这会根据我想要的内容进行排序.

This sorts it according to what I want.

但是我得到的结果在List<FooSelect>对象中，尽管我想要在List<Foo>中.

But the result I get is in List<FooSelect> object, though I want it in List<Foo>.

排序后如何更改映射?

我要在

//Stream<Foo> after it is sorted.

我想要类似的东西

List<Foo> li = same result of code above;

---

Class : FooSelect
just has some String fields
string FooKey
string FooTKey

以及该方法的getter和setter(其中一个是我正在排序的getFoosKey)

and getters and setters for that (one of them is getFoosKey by which I am sorting)

Class: Foo
private FooSelect select
private FooInsert insert

Foo(select, insert)

public FooSelect getSelect() {
return select; }

相同的设置方法.

推荐答案

您可以在Comparator.comparing中使用lambda表达式代替方法引用

You can use lambda expression in Comparator.comparing instead of method reference

List<Foo> res = foos.stream()             
                    .sorted(Comparator.comparing(fo->fo.getSelect().getFooKey()))
                    .collect(Collectors.toList());

对于排序，您甚至不需要流

For just sorting you don't even need stream

foos.sort(Comparator.comparing(fo->fo.getSelect().getFooKey()));

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