How not to repeat math operations two times in calculator app?

Question

I have made a simple calculator in "Kotlin" using an android studio the problem I got and I don\'t have a way to fix it is how not to repeat the math operations after

Answer 1

If You don't want to add two operators next to each other You have to check if last character is the operator. It will look something like this:

fun appendOnExpresstion(string: String, canClear: Boolean)
{
    if (tvResult.text.isNotEmpty())
    {
        tvExpression.text = ""
    }
    if (canClear)
    {
        tvResult.text = ""
        tvExpression.append(string)
    }
    else
    {
        if (tvExpression.text.lastOrNull() !in arrayOf('+', '-', '*', '/')) // You are adding operator so You have to check if last char is oparetor
        {
            tvExpression.append(tvResult.text)
            tvExpression.append(string)
        }
        tvResult.text = ""
    }
}