Question

我定义了一个自定义对话框类跟随构建器模式。我的代码没问题。但是现在我想重建以便能够在java 8 lambda上使用

CustomDialogList.kt

class CustomDialogList(context: Context,
                       private var title: Int?,
                       private var icon: Int?,
                       private var map: Map<String, Any>,
                       private var listner: OnItemClickListener) : Dialog(context) {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.custom_dialog_list)
        txtTitle.text = context.getString(title!!)
        txtTitle.setCompoundDrawablesWithIntrinsicBounds(icon!!, 0, 0, 0)

        val listString: MutableList<String> = mutableListOf()
        val listObject: MutableList<Any> = mutableListOf()
        for ((k, v) in map) {
            listString.add(k)
            listObject.add(v)
        }

        val adapter = ArrayAdapter<String>(context, android.R.layout.simple_list_item_1, listString)
        listView.adapter = adapter
        listView.setOnItemClickListener { _, _, i, _ ->
            listner.onClickResult(this, listObject[i], listString[i], i)
        }
    }

    interface OnItemClickListener {
        fun onClickResult(dialog: CustomDialogList, obj: Any?, text: String, position: Int)
    }

    class Builder(private var context: Context) {

        private var listner: OnItemClickListener? = null
        private var title: Int? = null
        private var icon: Int? = null
        private var map: Map<String, Any> = mapOf()

        fun withTitle(title: Int): Builder {
            this.title = title
            return this
        }

        fun withIcon(icon: Int): Builder {
            this.icon = icon
            return this
        }

        fun withMap(map: Map<String, Any>): Builder {
            this.map = map
            return this
        }

        fun setOnItemClick(listner: OnItemClickListener): Builder {
            this.listner = listner
            return this
        }

        fun show() = CustomDialogList(context, title, icon, map, listner!!).show()
    }
}

定义

后的语法

CustomDialogList.Builder(this)
                .withTitle(R.string.add)
                .withIcon(R.drawable.ic_add)
                .withMap(mapOf())
                .setOnItemClick(object : CustomDialogList.OnItemClickListener {
                    override fun onClickResult(dialog: CustomDialogList, obj: Any?, text: String, position: Int) {
                        // do something
                        dialog.dismiss()
                    }
                })
                .show()

这是一个我想要构建的例子

CustomDialogList.Builder(this)
                .withTitle(R.string.add)
                .withIcon(R.drawable.ic_add)
                .withMap(mapOf())
                .setOnItemClick({ dialog, obj, text, position ->
                    // do something
                    dialog.dismiss()
                })
                .show()

这是我第一次发帖提问，希望大家都能原谅我的英语不好。谢谢你，任何人都可以帮助我:)。

Answer 1

KT-7770：SAM不适用于Kotlin中定义的接口。

换句话说，lambda表达式

{ dialog, obj, text, position -> ... }

可以是Java功能接口或Kotlin功能，但不能是Kotlin功能接口。

如果删除OnItemClickListener界面并写入

typealias OnItemClickListener = (CustomDialogList, Any?, String, Int) -> Unit

在顶级，或修改类型签名，您的第二个示例将起作用（并且您的第一个示例将失败）。如果您改为使用Java定义接口，则两者都可以。

kotlin android - 使用Builder Pattern和Java 8 lambda的自定义对话框

1 个答案: