仅接受允许的字符EditText。使用正则表达式和输入过滤器kotlin

import android.text.InputFilter
import android.text.Spanned
import android.widget.EditText

fun setAllowedCharacters(editText: EditText, allowedPattern: String) {
    val filter = object : InputFilter {
        val regex = Regex(allowedPattern)

        override fun filter(
            source: CharSequence?,
            start: Int,
            end: Int,
            dest: Spanned?,
            dstart: Int,
            dend: Int
        ): CharSequence? {
            val input = dest?.subSequence(0, dstart).toString() + source?.subSequence(start, end) + dest?.subSequence(dend, dest.length).toString()
            return if (regex.matches(input)) {
                null // Accept the input
            } else {
                "" // Reject the input
            }
        }
    }

    editText.filters = arrayOf(filter)
}

val editText = findViewById<EditText>(R.id.editText)
setAllowedCharacters(editText, "[a-zA-Z0-9]+")