Mask an EditText with Phone Number Format NaN like in PhoneNumberUtils

Question

I want to make user inputted phone number in an editText to dynamically change format every time the user inputs a number. That is, when user inputs up to 4 digits, like 714

Answer 1

Here is my solution

How run in Activity/Fragment (f.e in onViewCreated):

//field in class
private val exampleIdValidator by lazy { ExampleIdWatcher(exampleIdField.editText!!) }

exampleIdField.editText?.addTextChangedListener(exampleIdValidator)

Validatior class:

    import android.text.Editable
    import android.text.TextWatcher
    import android.widget.EditText

    class ExampleIdWatcher(exampleIdInput: EditText) : TextWatcher {

        private var exampleIdInput: EditText = exampleIdInput

        override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) {
        }

        override fun onTextChanged(userInput: CharSequence?, start: Int, before: Int, count: Int) {
            if (userInput!!.isNotEmpty() && !areSpacesCorrect(userInput)) {

                val stringTextWithoutWhiteSpaces: String = userInput.toString().replace(" ", "")

                val textSB: StringBuilder = StringBuilder(stringTextWithoutWhiteSpaces)

                when {
                    textSB.length > 8 -> {
                        setSpacesAndCursorPosition(textSB, 2, 6, 10)
                    }
                    textSB.length > 5 -> {
                        setSpacesAndCursorPosition(textSB, 2, 6)
                    }
                    textSB.length > 2 -> {
                        setSpacesAndCursorPosition(textSB, 2)
                    }
                }
            }
        }

        override fun afterTextChanged(s: Editable?) {
        }

        private fun setSpacesAndCursorPosition(textSB: StringBuilder, vararg ts: Int) {
            for (t in ts) // ts is an Array
                textSB.insert(t, SPACE_CHAR)
            val currentCursorPosition = getCursorPosition(exampleIdInput.selectionStart)
            exampleIdInput.setText(textSB.toString())
            exampleIdInput.setSelection(currentCursorPosition)
        }

        private fun getCursorPosition(currentCursorPosition: Int): Int {
            return if (EXAMPLE_ID_SPACE_CHAR_CURSOR_POSITIONS.contains(currentCursorPosition)) {
                currentCursorPosition + 1
            } else {
                currentCursorPosition
            }
        }

        private fun areSpacesCorrect(userInput: CharSequence?): Boolean {
            EXAMPLE_ID_SPACE_CHAR_INDEXES.forEach {
                if (userInput!!.length > it && userInput[it].toString() != SPACE_CHAR) {
                    return false
                }
            }
            return true
        }

        companion object {
            private val EXAMPLE_ID_SPACE_CHAR_INDEXES: List = listOf(2, 6, 10)
            private val EXAMPLE_ID_SPACE_CHAR_CURSOR_POSITIONS: List = EXAMPLE_ID_SPACE_CHAR_INDEXES.map { it + 1 }
            private const val SPACE_CHAR: String = " "
        }
    }

Layout:

Result is:

XX XXX XXX XXX