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Kotlinコードでシンプルなコンストラクタ

Posted at

書いていたコード

CustomViewを実装する際にコンストラクタをたくさん書いておりました。すっきりまとめる場合には@JvmOverloadsを使えばいいことを知りました。

今までこんな風に書いていました。

class PickerView: View {
    constructor(context: Context) : this(context, null) {
        prepare()
    }
    constructor(context: Context, attrs: AttributeSet?, defStyleAttr: Int) : super(context, attrs, defStyleAttr) {
        prepare()
    }
    constructor(context: Context, attrs: AttributeSet?) : super(context, attrs) {
        prepare()
    }

    fun prepare() {
    }
}

@JvmOverloadsアノテーションを使う

@JvmOverloadsを使うとすっきりできますね!

class PickerView @JvmOverloads constructor(
        context: Context,
        attrs: AttributeSet? = null,
        defStyleAttr: Int = 0
) : View(context, attrs, defStyleAttr) {
    init {
        prepare()
    }

    fun prepare() {
    }
}

他のものもすっきり書けそうでした。

class PickerViewPager : ViewPager {
    @JvmOverloads constructor(context: Context, attrs: AttributeSet? = null) : super(context, attrs)
}

参考にさせていただきました!!
http://qiita.com/jmatsu/items/6c141ba0acb13409c7bf

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