Android开发(Kotlin) 扩展函数和运算符重载的使用

fun ClassName.methodName(param1:Int,param2:Int):Int{
}

fun String.lettersCount(): Int {
    var count = 0
    for (char in this) {
        if (char.isLetter()) {
            count++
        }
    }
    return count
}

   "ASDGHJH1564564&*^&*%&^".lettersCount()

class obj{
	operator fun plus(obj:Obj):Obj{
	}
}

class PowerConsumption(val value: Int) {
}

class PowerConsumption(val value: Int) {
    operator fun plus(powerConsumption: PowerConsumption): PowerConsumption {
        val sum = value + powerConsumption.value
        return PowerConsumption(sum)
    }
}

        val powerConsumption1 = PowerConsumption(50)
        val powerConsumption2 = PowerConsumption(100)
        val powerConsumption3 = powerConsumption1 + powerConsumption2
        println(powerConsumption3.value)

    fun getRandomLengthString(str: String):String{
        val n = (1..20).random()
        val builder = StringBuilder()
        repeat(n){
            builder.append(str)
        }
        return  builder.toString()
    }

operator fun String.times(n: Int): String {
    val builder = StringBuilder()
    repeat(n) {
        builder.append(this)
    }
    return builder.toString()
}

        val str = "mnl"*3
        println(str)

mnlmnlmnl