kotlin作用域函数let/with/run/apply/also

let

常用语非空判断，【it】增加代码可读性

object?.let {
    setText(it.objText)
    setBackgroundColor(it.objColor)
}

also

常用语非空判断，【it】增加代码可读性，适合链式调用

var object?.also{
    setText(it.objText)
    setBackgroundColor(it.objColor)
}.also{
    ...doSomething(it.objParam)
}

run

适合初始化并设置多条属性，不需要返回值，例如：

findViewById<RecyclerView>(R.id.recycler).run {
            layoutManager = LinearLayoutManager(this@MainActivity)
            adapter = listAdapter
            addItemDecoration(DividerItemDecoration(this@MainActivity, LinearLayout.VERTICAL))
        }

apply

适合初始化并设置多条属性并返回自身对象，例如：

private val paint = Paint().apply {
        isAntiAlias = false
        style = Paint.Style.STROKE
        color = getContext().getColor(R.color.colorAccent)
        strokeWidth = 4f.dp2px()
    }

with

val result:Int = with(supportData) {
            showInfo()
            spvTotal
        }
        with(supportDataNullAble) {
            this?.showInfo()
        }