android - 如何将原始类型(String)的集合存储到数据库中

Question

我正在尝试使用 ORMLite 将我的类映射到 SQLite 数据库，但我在存储字符串集合时遇到了问题我有这个错误:

java.lang.IllegalArgumentException: No fields have a DatabaseField annotation in
     class java.lang.String

这个错误是不言自明的，但是我应该如何存储字符串集合我应该扩展 String 类并添加所需的注释才能做到这一点吗？ 在该字段的注释中，我添加了 datatype.serializable 但这也行不通。 这是我遇到问题的类(class):

@DatabaseTable(tableName = "parameters")

public class Parameters {

    // id is generated by the database and set on the object automagically
    @DatabaseField(generatedId = true)
    int id_parameters;

    @DatabaseField(canBeNull = true)
    @JsonProperty("id")
    private Integer id;

    @DatabaseField(canBeNull = false)
    @JsonProperty("account_id")
    private Integer account_id;

    @ForeignCollectionField
    @JsonProperty("languages")
    private Collection<String> languages;
    ...
}

有问题的领域是语言!

Answer 1

是的，您不能只收集字符串。您将需要创建一个包装类，其中包含一个 String 字段以及一个外部 Parameters 字段:

public class Language {
    @DatabaseField(generatedId = true)
    int id;
    @DatabaseField
    String language;
    @DatabaseField(foreign = true)
    Parameters parameters;
}

这是 description of foreign collections从调频。引用:

Remember that when you have a ForeignCollection field, the class in the collection must (in this example Order) must have a foreign field for the class that has the collection (in this example Account). If Account has a foreign collection of Orders, then Order must have an Account foreign field. It is required so ORMLite can find the orders that match a particular account.