mycode.kt

fun EditText.addThousandSeparator() {
            this.addTextChangedListener(object : TextWatcher {
                private var current = ""
                override fun beforeTextChanged(
                    s: CharSequence?,
                    start: Int,
                    count: Int,
                    after: Int
                ) {
                }

                override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {}

                override fun afterTextChanged(s: Editable?) {
                    if (s.toString() != current) {
                        val userInput = s.toString().replace("[^\\d]".toRegex(), "")
                        if (userInput.isNotEmpty()) {
                            val formatted = StringBuilder()
                            val symbols = DecimalFormatSymbols.getInstance()
                            val separator = symbols.groupingSeparator

                            var counter = 0
                            for (i in userInput.length - 1 downTo 0) {
                                formatted.append(userInput[i])
                                counter++
                                if (counter % 3 == 0 && i != 0) {
                                    formatted.append(separator)
                                }
                            }
                            current = formatted.reverse().toString()

                            val selectionStart = this@addThousandSeparator.selectionStart
                            val newSelectionStart =
                                calculateCursorPosition(selectionStart, userInput, current)

                            this@addThousandSeparator.removeTextChangedListener(this)
                            this@addThousandSeparator.setText(current)
                            this@addThousandSeparator.setSelection(newSelectionStart)
                            this@addThousandSeparator.addTextChangedListener(this)
                        }
                    }
                }
            })
        }

        private fun calculateCursorPosition(
            start: Int,
            originalText: String,
            formattedText: String
        ): Int {
            val symbols = DecimalFormatSymbols.getInstance()
            val separator = symbols.groupingSeparator
            var newPosition = start

            for (i in 0 until start) {
                if (i < formattedText.length && formattedText[i] == separator) {
                    newPosition++
                }
            }

            return newPosition.coerceAtMost(formattedText.length)
        }