Java 8流API-根据条件进行过滤并收集对象 [英] Java 8 stream API- Filter based on condition and collect the object

问题描述

在Java 8中，根据某些过滤条件收集emp对象.

In java 8 , collect emp object based on some filter condition.

在主要班级

List<Emp> empList = Arrays.asList(
    new Emp("aaa", language1), 
    new Emp("cc", language2),
    new Emp("bb", language3), 
    new Emp("dd", language3)
);

empList.stream()
    .flatMap(s->s.getLanguage().stream())
    .filter(s->s.equals("java"))
    .forEach(System.out::println); //Here just i am printing. 

实际上我需要收集new List<EMP>

如何收集都具有语言"java"的emp对象.我该怎么办?

How to collect emp object who are all have language "java". How can I do?

推荐答案

如果最终要收集Emp对象，则不应使用flatMap，因为它会将每个元素都更改为其他元素，并且可能会相当很难将它们映射回去.

You should not use flatMap if you want to collect Emp objects in the end because it will change every element to something else and it can be quite hard to map them back.

您应该将所有逻辑放在filter中:如果getLanguage包含"java"，请保留Emp对象".

You should put all your logic in a filter: "keep the Emp object if getLanguage contains "java"".

empList.stream()
    .filter(x->x.getLanguage().contains("java"))
    .collect(Collectors.toList());

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