List<User> to Map<String,List<User>>
How to convert List of a POJO to Map<String,List> in Java Stream?
uSy62nMkdH · Oct 9, 2022 · 2226 viewsThis topic created in 1336 days ago, the information mentioned may be changed or developed.
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1
ebony0319 Oct 9, 2022
what's the key?
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2
jorneyr Oct 9, 2022
users.stream().collect(Collectors.toMap(User::getUsername, u -> u, (o, n) -> o));
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3
anakinsky Oct 9, 2022  5
users.stream().collect(Collectors.groupingBy(User::getKey);
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4
Aresxue Oct 9, 2022
users.stream().collect(Collectors.groupingBy(User::getKey);
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5
KingOfUSA Oct 9, 2022
2 楼的写法好点，当 key 有重复的时候可以容错
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6
selca Oct 9, 2022
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8
lazyfighter Oct 9, 2022
@KingOfUSA bug 了，看清楚楼主的需求， 二楼的返回值是啥？
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9
KingOfUSA Oct 9, 2022
@lazyfighter 啊，我错了，，，
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10
xuanbg Oct 9, 2022
3 楼正解，就是按 User 对象的某个字段分组，然后以分组字段的值为 key 把对应分组的内容放进 value 。
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