小编eli*_*yro的帖子

我正在使用Room持久性库开发Android应用程序.我有一个User和一个Car实体

@Entity(tableName = "users")
public class User {

    @PrimaryKey
    @NonNull
    private int id;
    private String name;

    public User(@NonNull int id, String name) {
        this.id = id;
        this.name = name;
    }
}

和

@Entity(tableName = "cars", foreignKeys = @ForeignKey(parentColumns  = 
"id", childColumns = "userId", entity = User.class))
public class Car {

    @PrimaryKey(autoGenerate = true)
    private int id;
    private int userId;
    private String brand;

    public Car(int userId, String brand) {
        this.userId = userId;
        this.brand = brand;
    }
}

我还创建了一个UserWithCar类,如下所示:

public class UserWithCar …