<分区>
我想按 id()
对用户列表进行分组使用 Java 流。
例如,我有 List: new User(1L, "First"), new User(2L, "Second")
.
如何将此列表分组以获得 Map<Long, User>
?
1L -> new User(1L, "First"),
2L -> new User(2L, "Second")
用户.java
public final class User {
final Long id;
final String name;
public User(final Long id, final String name) {
this.id = id;
this.name = name;
}
public Long id() {
return this.id;
}
public String name() {
return this.name;
}
}