Kotlin实践细节

by lazy

private val topCaseAdapter by lazy {
    ProfileTopCaseAdapter()
}
private val activity by lazy {
    getActivity() as MidderProductContrastActivity
}

回调 函数

定义var pointClick:((remarkDocCaseModel: RemarkDocItemCase)->Unit)? = null;

注册   caseView.pointClick = {
        it.xxx)
    }
触发   pointClick?.let {
         pointClick?.invoke(remarkDocCaseModel)
           }
多参数：
var imgClickBlock: ((String, ImageView) -> Unit)? = null //正常图片点
注册
adapter.imgClickBlock = { url, v ->
        ViewUtils.showImage(v, arrayListOf(url), context, 0)
    }

参数回调

fun processPreLogin(
    viewModelScope: CoroutineScope,
    userRepo: UserRepository,
    results: ((result: Resource) -> Unit),
): Boolean {
 }

image.png

数据模型 ？

val data = ArrayList()

判空

 val caseView = holder.itemView as? DocItemCaseView ?: return

for 循环

for (i in 0 until 10) { 
    }
for (index in 0 until topCaseRv.childCount) {
    }
item.bean.list.forEach{                  
  }

 childViewLoop@ for (index in 0 until mAdapter.data.size) {
    continue@childViewLoop
     if (!result) {
      break@innerViewLoop
       }
    }

when 语句

  when ((holder.layoutPosition + 1).toString()) {
                "1" -> R.drawable.doc_hot_top1
                "2" -> R.drawable.doc_hot_top2
                "3" -> R.drawable.doc_hot_top3
                else -> 0
            }

常量

 companion object {
    const val FROM_TYPE_TAB = "0"
    const val FROM_TYPE_DIALOG = "1"

}

隐藏软键盘

private fun hideKeyboard(rootView: View?) {
    var v = rootView
    if (v == null) {
        v = View(mContext)
    }
    val imm = mContext.getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager
    imm.hideSoftInputFromWindow(v.windowToken, InputMethodManager.RESULT_UNCHANGED_SHOWN)
}

run

remarkDocCaseModel.after_operation?.let { ok }?:run{ no }
bean.sh_discount?.let {
        if (it.title.isNotBlank()) {
            tv_discounts_explain.text = it.title
            tv_discounts_explain.setTextColor(DrawableUtils.praceColor(it.title_color, ResUtils.getColor(R.color.color_FF4040)))
        } else {
            tv_discounts_explain.visibility = View.GONE
        }
    }?:run {
        tv_discounts_explain.visibility = View.GONE
    }

RecyclerView

不滑动 android:overScrollMode="never"

as 强转 is 是某种类型

val mView = holder.itemView as? ItemView ?: return

判空 有疑问

//isNotEmpty(str) 等价于 str != null && str.length > 0
//isNotBlank(str) 等价于 str != null && str.length > 0 && str.trim().length > 0
//即：
//isNotEmpty(str) + && str.trim().length > 0 = isNotBlank(str)
//同理
//isEmpty         等价于 str == null || str.length == 0
//isBlank         等价于 str == null || str.length == 0 || str.trim().length == 0
//
//str.length > 0 && str.trim().length > 0       --->      str.length > 0

协程

image.png

image.png

continue break

    private fun checkExcuteNext(): Boolean {
    var result = true
    childViewLoop@ for (item in mAdapter.data) {
        if (item.itemType == 0)continue@childViewLoop
            val viewHolder =
                recycleView.findViewHolderForLayoutPosition(item.itemType)
            result = (viewHolder?.itemView as ICheckItem).check()
            if (!result) {
                break@childViewLoop
            }
        }
    return result
}

forEach break

fun main(args: Array) {
val arr = intArrayOf(1,2,3,4,5,6,7)
run breaking@{
    
    arr.forEach continuing@{
        if (it == 4) return@breaking
        println("value:$it")
    }
    }
  println("this is End")
  }

forEach continuing

fun main(args: Array) {
val arr = intArrayOf(1,2,3,4,5,6,7)
arr.forEach continuing@{
    if (it == 4) return@continuing
    println("value:$it")
}
println("this is End")
}

初始化属性时--Kotlin 的属性委托语法

private val viewModel: LoginViewModel by viewModels()

使用 Elvis 运算符提前从函数返回结果

fun validateAccount(account: Account?) {
val accountName = account?.name?.trim() ?: "Default name"
// account cannot be null beyond this point
account ?: return
}

小细节

https://www.jianshu.com/p/3acd0c96b79c
https://www.sohu.com/a/538859213_121124365