Phone Number Watcher is utility class to format mobile number in android 000-000-0000, In most of application we required phone number formater, so that I created gist, so easily get whenever required. Hope it will help.

PhoneNumberWatcher.kt

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


/**
 * @author Hitesh
 * @version 1.0
 * @since 14-08-2019
 */
class PhoneNumberWatcher : TextWatcher {
    private val mEditText: EditText
    private var beforeText: String? = null
    private var type: Int = 0

    constructor(editText: EditText) {
        this.mEditText = editText
    }

    fun setType(type: Int) {
        this.type = type
    }

    override fun beforeTextChanged(s: CharSequence, start: Int, count: Int, after: Int) {
        beforeText = mEditText.text.toString().trim { it <= ' ' }
    }

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

    override fun afterTextChanged(s: Editable) {
        mEditText.removeTextChangedListener(this)

        var text = mEditText.text.toString()

        var strictNTxt = strictTrim(text)
        val strictOTxt = strictTrim(beforeText!!)

        if (strictNTxt.length > 10) {
            strictNTxt = strictOTxt
            text = strictNTxt
        }

        if (text.length > beforeText!!.length) {
            text = strictNTxt
        } else {
            if (strictOTxt.length > strictNTxt.length) {
                text = strictNTxt
            } else {
                val index = match(text, beforeText!!)
                if (index == 0) {
                    //Do Nothing
                } else if (index == -1) {
                    if (text.length > 0 && !Character.isLetterOrDigit(beforeText!![beforeText!!.length - 1])) {
                        text = text.substring(0, text.length - 1)
                    }
                } else {
                    if (!Character.isLetterOrDigit(beforeText!![index])) {
                        text = text.substring(0, index - 1) + text.substring(index - 1, text.length)
                    } else {
                        //Do Nothing
                    }
                }
            }
        }


        val formattedValue = formatPhoneNumber(text)

        mEditText.setText(formattedValue)
        mEditText.setSelection(mEditText.text.length)
        mEditText.addTextChangedListener(this)
    }

    private fun strictTrim(text: String): String {
        val sb = StringBuilder()
        for (c in text.toCharArray()) {
            if (Character.isLetterOrDigit(c)) {
                sb.append(c)
            }
        }
        return sb.toString()
    }

    fun formatPhoneNumber(text: String): String {
        var text = text
        text = trim(text)
        if (text.length > 10) {
            text = text.substring(0, 3) + "-" + text.substring(3, 6) + "-" + text.substring(
                6,
                10
            ) + "(" + text.substring(10) + ")"
        } else if (text.length > 6) {
            text = text.substring(0, 3) + "-" + text.substring(3, 6) + "-" + text.substring(6)
        } else if (text.length > 3) {
            text = text.substring(0, 3) + "-" + text.substring(3)
        }
        return text
    }

    fun trim(text: String): String {
        var text = text
        text = text.trim { it <= ' ' }
        text = text.replace("-", "")
        text = text.replace("(", "")
        text = text.replace(")", "")
        return text
    }

    private fun match(text1: String, text2: String): Int {
        val textArray1 = text1.toLowerCase().toCharArray()
        val textArray2 = text2.toLowerCase().toCharArray()
        val minLength = Math.min(textArray1.size, textArray2.size)
        for (i in 0 until minLength) {
            if (textArray1[i] != textArray2[i]) {
                return i
            }
        }
        return -1
    }

    /*
     * This will remove all symbol
     */
    fun getStrippedPhoneNumber(phoneNumber: String): String {
        // Remove all non-digit characters
        return phoneNumber.replace("\\D+".toRegex(), "")
    }
}

/**
* How to use with edit text
*/
val edtPhoneNumber = mViewDataBinding.edtContactPhone.getEditText()
val mPhoneNumberWatcher = PhoneNumberWatcher(edtPhoneNumber)
edtPhoneNumber.addTextChangedListener(mPhoneNumberWatcher)