class User{
private String id;
private String code;
private String name;
}List list;这么个列表,我想单独取出code,假设有5个数据,有三个code是1,两个code是2,我想用java8的stream的方法操作取出一个列表或者set,例如List这样,里面放了一个1和一个2,就是同时去重,怎么写诶
2 回答

慕田峪9158850
TA贡献1794条经验 获得超7个赞
public static void main(String[] args) { List<User> users = new ArrayList<>(); users.add(new User("1","1","张三")); users.add(new User("2","1","李四")); users.add(new User("3","2","王五")); users.add(new User("4","2","小明")); users.add(new User("5","1","小三")); Set<String> codeExists = new HashSet<>(); users = users.stream().filter((V)->{ String code = V.getCode(); if(codeExists.contains(code)){ return false; }else{ codeExists.add(code); return true; } }).collect(Collectors.toList()); System.out.println(users);

POPMUISE
TA贡献1765条经验 获得超5个赞
class User{ String code; public String getCode() { return code; } } public class Test { public static void main(String args[]){ List<User> users = new ArrayList<>(); users.stream() .collect(Collectors.groupingBy(User::getCode)) .keySet(); } }
先分组,分完组后只拿keySet就行了
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