android - 如何在 Kotlin Android 中为数据类创建构造函数？

Question

如何在 Kotlin Android 中为数据类创建构造函数？

data class EventItem(
        @SerializedName("dateEvent")
        val dateEvent: String,
        @SerializedName("dateEventLocal")
        val dateEventLocal: Any,
        @SerializedName("idAwayTeam")
        val idAwayTeam: String,
        @SerializedName("idEvent")
        val idEvent: String,
        @SerializedName("idHomeTeam")
        val idHomeTeam: String,
        @SerializedName("idLeague")
        val idLeague: String,
        @SerializedName("idSoccerXML")
        val idSoccerXML: String,
        @SerializedName("intAwayScore")
        val intAwayScore: Any,
        @SerializedName("intAwayShots")
        val intAwayShots: Any,
        @SerializedName("intHomeScore")
        val intHomeScore: Any,
        @SerializedName("intHomeShots")
        val intHomeShots: Any,
        @SerializedName("intRound")
        val intRound: String,
        @SerializedName("intSpectators")
        val intSpectators: Any,
        @SerializedName("strAwayFormation")
        val strAwayFormation: Any,
        @SerializedName("strAwayGoalDetails")
        val strAwayGoalDetails: String,
        @SerializedName("strAwayLineupDefense")
        val strAwayLineupDefense: String,
        @SerializedName("strAwayLineupForward")
        val strAwayLineupForward: String,
        @SerializedName("strAwayLineupGoalkeeper")
        val strAwayLineupGoalkeeper: String,
        @SerializedName("strAwayLineupMidfield")
        val strAwayLineupMidfield: String,
        @SerializedName("strAwayLineupSubstitutes")
        val strAwayLineupSubstitutes: String,
        @SerializedName("strAwayRedCards")
        val strAwayRedCards: String,
        @SerializedName("strAwayTeam")
        val strAwayTeam: String,
        @SerializedName("strAwayYellowCards")
        val strAwayYellowCards: String,
        @SerializedName("strBanner")
        val strBanner: Any,
        @SerializedName("strCircuit")
        val strCircuit: Any,
        @SerializedName("strCity")
        val strCity: Any,
        @SerializedName("strCountry")
        val strCountry: Any,
        @SerializedName("strDate")
        val strDate: String,
        @SerializedName("strDescriptionEN")
        val strDescriptionEN: Any,
        @SerializedName("strEvent")
        val strEvent: String,
        @SerializedName("strEventAlternate")
        val strEventAlternate: String,
        @SerializedName("strFanart")
        val strFanart: Any,
        @SerializedName("strFilename")
        val strFilename: String,
        @SerializedName("strHomeFormation")
        val strHomeFormation: Any,
        @SerializedName("strHomeGoalDetails")
        val strHomeGoalDetails: String,
        @SerializedName("strHomeLineupDefense")
        val strHomeLineupDefense: String,
        @SerializedName("strHomeLineupForward")
        val strHomeLineupForward: String,
        @SerializedName("strHomeLineupGoalkeeper")
        val strHomeLineupGoalkeeper: String,
        @SerializedName("strHomeLineupMidfield")
        val strHomeLineupMidfield: String,
        @SerializedName("strHomeLineupSubstitutes")
        val strHomeLineupSubstitutes: String,
        @SerializedName("strHomeRedCards")
        val strHomeRedCards: String,
        @SerializedName("strHomeTeam")
        val strHomeTeam: String,
        @SerializedName("strHomeYellowCards")
        val strHomeYellowCards: String,
        @SerializedName("strLeague")
        val strLeague: String,
        @SerializedName("strLocked")
        val strLocked: String,
        @SerializedName("strMap")
        val strMap: Any,
        @SerializedName("strPoster")
        val strPoster: Any,
        @SerializedName("strResult")
        val strResult: Any,
        @SerializedName("strSeason")
        val strSeason: String,
        @SerializedName("strSport")
        val strSport: String,
        @SerializedName("strTVStation")
        val strTVStation: Any,
        @SerializedName("strThumb")
        val strThumb: Any,
        @SerializedName("strTime")
        val strTime: String,
        @SerializedName("strTimeLocal")
        val strTimeLocal: String,
        @SerializedName("strTweet1")
        val strTweet1: Any,
        @SerializedName("strTweet2")
        val strTweet2: Any,
        @SerializedName("strTweet3")
        val strTweet3: Any,
        @SerializedName("strVideo")
        val strVideo: Any
    ) {
        constructor(
            idEvent: String,
            strEvent: String,
            strDate: String,
            idHomeTeam: String,
            strHomeTeam: String,
            intHomeScore: Any,
            idAwayTeam: String,
            strAwayTeam: String,
            intAwayScore: Any
            ) : this(idEvent, strEvent, strDate, idHomeTeam, strHomeTeam,  intHomeScore, idAwayTeam, strAwayTeam, intAwayScore)
    }

截图:/image/riGkU.png

如何在 Kotlin Android 中为数据类创建构造函数？

我尝试创建构造函数。但是，我得到“委托(delegate)调用链中有一个循环”请更正我的代码并告诉我解决方案。 . .

Answer 1

对于数据类，类头中定义的构造函数是主构造函数。它不能委托(delegate)给该类中的任何其他构造函数(尽管它可以委托(delegate)给父类(super class)构造函数)。

但是，您可以在类的主体中定义辅助构造函数，只要这些构造函数委托(delegate)给主构造函数即可。例如:

data class EventItem(val dateEvent: String) {

    constructor(date: Date) : this(date.toString())
}

您发布的代码中的问题是您的辅助构造函数试图委托(delegate)回自身。您必须改为委托(delegate)给主构造函数，这意味着您需要能够确定辅助构造函数中缺少的所有参数的值。