I'm a beginner in Android software development. I'm making a calculator app to test my skills. In a calculator there are 0-9 numeric and some others operators like +, -, *, / etc. In the time of Equal functionality, I have to make sure that the last string of the TextView has any number (0-9), not any operators.
My equal fun is like that:
fun onEqual(view: View) {
if (tv_input.text.contains("0-9")) {
Toast.makeText(this, "Last string is a number, not operator", Toast.LENGTH_SHORT).show()
}
}
You need to use Kotlin regular expression matches
val lastString = "573" // input
val pattern = "-?\\d+(\\.\\d+)?".toRegex()
/**
-? allows zero or more - for negative numbers in the string.
\\d+ checks the string must have at least 1 or more numbers (\\d).
(\\.\\d+)? allows zero or more of the given pattern (\\.\\d+)
In which \\. checks if the string contains . (decimal points) or not
If yes, it should be followed by at least one or more number \\d+.
**/
val isLastString = pattern.matches(lastString)
https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.text/ends-with.html
fun String.endsWith(
suffix: String,
ignoreCase: Boolean = false
): Boolean
Returns true if this string ends with the specified suffix.
Thanks everyone. I did my own solution.
Here is the code I've wrote:
fun onEqual(view: View) {
if (!tv_input.text.toString().equals("")) {
val last = tv_input.text.toString()
val lastNumber: String = last.get(last.length - 1).toString()
Toast.makeText(this, lastNumber, Toast.LENGTH_SHORT).show()
}else {
return
}
}