房间持久性：实体和Pojos必须具有可用的公共构造函数 [英] Room Persistence: Entities and Pojos must have a usable public constructor

问题描述

我正在尝试通过Room Persistence库将数据库添加到我的android应用中，并且出现此错误：

I am trying to add a database to my android app through the Room Persistence library and i am getting this error:

错误：实体和Pojos必须具有可用的公共构造函数。您可以有一个空的构造函数或一个其参数与字段匹配的构造函数（按名称和类型）。
尝试了以下构造函数，但未能匹配：
User（int，java.lang.String，java.lang.String，int，int，int，java.lang.String）-> [param ：id->匹配字段：不匹配，参数：名称->匹配字段：不匹配，参数：性别->匹配字段：不匹配，参数：年龄->匹配字段：不匹配，参数：重量->匹配字段：不匹配，参数：高度->匹配字段：不匹配，参数：锻炼->匹配字段：不匹配]

error: Entities and Pojos must have a usable public constructor. You can have an empty constructor or a constructor whose parameters match the fields (by name and type). Tried the following constructors but they failed to match: User(int,java.lang.String,java.lang.String,int,int,int,java.lang.String) -> [param:id -> matched field:unmatched, param:name -> matched field:unmatched, param:gender -> matched field:unmatched, param:age -> matched field:unmatched, param:weight -> matched field:unmatched, param:height -> matched field:unmatched, param:workout -> matched field:unmatched]

这是我的代码：

    @Entity
    public class User {

@PrimaryKey
private int userId;
private String userName;
private String userGender;
private int userAge;
private int userWeight;
private int userHeight;
private String workoutPlan;


public User(int id, String name, String gender, int age, int weight, int height, String workout) {

    this.userId = id;
    this.userName = name;
    this.userGender = gender;
    this.userAge = age;
    this.userWeight = weight;
    this.userHeight = height;
    this.workoutPlan = workout;

} ...

有人可以告诉我我在做什么错误或我错过了什么？

Can someone please tell me what i am doing wrong or what i missed?

推荐答案

请更改参数名称，使其与实体属性匹配。

Please change names of the parameters such that it matches entity attributes.

  public User(int userId, String userName, String userGender, int userAge, int userWeight, int userHeight, String workoutPlan) {
    this.userId = userId;
    this.userName = userName;
    this.userGender = userGender;
    this.userAge = userAge;
    this.userWeight = userWeight;
    this.userHeight = userHeight;
    this.workoutPlan = workoutPlan;
  } ...

为了保持持久性，它在Room中使用JavaBeans约定。有关更多信息：
https://developer.android .com / training / data-storage / room / defining-data＃java

For persistance, it uses JavaBeans conventions in Room. For more information: https://developer.android.com/training/data-storage/room/defining-data#java

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