单击按钮后如何更新 TextView 文本

Question

when i cick on number the TextView Doesnt change it supposed to show number when i click on them like the calculator that's my code i still in the first part of the app

 fun clicknumber(view: View) {

        var buselected = view as Button
        var tvnum = tv.text.toString()
       if (newOp){
            tv.text = ""
       }
        newOp=false


        when (buselected.id) {
           one.id-> tvnum += "1"
            two.id-> tvnum += "2"
            three.id-> tvnum += "3"
            four.id-> tvnum += "4"
            five.id-> tvnum += "5"
            six.id-> tvnum += "6"
            seven.id-> tvnum += "7"
            eight.id-> tvnum += +"8"
            nine.id-> tvnum += "9"
            dot.id-> tvnum += "."
            minusplus.id -> tvnum = "-" + tvnum
        }
    }
}

i think the problem is in the "tvnum" and i wanna to clear the textview when i do a new operation, i write the code but it doesnt work so good

Answer 1

You're assigning tvnum but you're doing nothing with it. You need to set the text in the TextView instead. tv.text = tvnum

Answer 2

Honestly saying i can't understand your question but still you can try this... Change the text of the view individually in each case. like tv.text = "---"