可以用stream方法
List<User> list = new ArrayList<>();
User u= new User("1", "123");
User u1 = new User("2", "456");
list.add(u);
list.add(u1);
Map<String, String> map = list.stream().collect(Collectors.toMap(User::getUserId, User::getPwd));
System.out.println("userId为1的密码:" + map.get("1"));
System.out.println("userId为2的密码:" + map.get("2"));
打印如下
userId为1的密码:123
userId为2的密码:456
user实体为
public class User {
private String id;
private String userId;
private String pwd;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getUserId() {
return userId;
}
public void setUserId(String userId) {
this.userId = userId;
}
public String getPwd() {
return pwd;
}
public void setPwd(String pwd) {
this.pwd = pwd;
}
public User(String userId, String pwd) {
this.userId = userId;
this.pwd = pwd;
}
}