Android Room Database忽略问题“尝试了以下构造函数，但它们不匹配”

问题描述

我的实体类别：

@Entity(tableName = "student")
data class Student(
    var name: String,var age: Int,var gpa: Double,var isSingle: Boolean,@PrimaryKey(autoGenerate = true)
    var id: Long = 0,@Ignore                           //don't create column in database,just for run time use
    var isSelected: Boolean = false                     
)

然后我像这样插入（在androidTest中测试）：

val student = Student("Sam",27,3.5,true)

studentDao.insert(student)

在添加@Ignore批注之后，它立即给我这个错误：

C:\Android Project\RoomTest\app\build\tmp\kapt3\stubs\debug\com\example\roomtest\database\Student.java:7: ����: 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).
public final class Student {
         ^
  Tried the following constructors but they failed to match:
  Student(java.lang.String,int,double,boolean,long) -> [param:name -> 
matched field:name,param:age -> matched field:age,param:gpa -> matched 
field:gpa,param:isSingle -> matched field:isSingle,param:isSelected -> 
matched field:unmatched,param:id -> matched field:id][WARN] Incremental 
annotation processing requested,but support is disabled because the 
following processors are not incremental: androidx.room.RoomProcessor 
(DYNAMIC).

解决方法

由于Room仍在编译期间生成Java类，并且问题出在默认值参数上，因此请尝试使用@JvmOverloads作为构造函数：

@Entity(tableName = "student")
data class Student @JvmOverloads constructor(
    var name: String,.....  

更新

有趣的是，here in documentation对此案没有提及特殊待遇。并且this issue已经存在，可以修复此文档。

从this issue到问题本身的结论是：

使用@JvmOverloads应该可以。在不远的将来有一天，我们可能会生成Kotlin，这不会成为问题