OTP Behaviour

Others.kt

private fun clearInputs() {
        val colorStateList = ColorStateList.valueOf(Color.RED)

        binding.apply {

            otp1.text.clear()
            otp2.text.clear()
            otp3.text.clear()
            otp4.text.clear()
            otp5.text.clear()
            otp6.text.clear()

            otp1.backgroundTintList = colorStateList
            otp2.backgroundTintList = colorStateList
            otp3.backgroundTintList = colorStateList
            otp4.backgroundTintList = colorStateList
            otp5.backgroundTintList = colorStateList
            otp6.backgroundTintList = colorStateList
        }

        setDefaultInputFocus()
    }

    private fun setDefaultInputFocus() {
        binding.apply {
            otp6.clearFocus()
            otp5.clearFocus()
            otp4.clearFocus()
            otp3.clearFocus()
            otp2.clearFocus()
            otp1.requestFocus()
        }
    }

SharedFocus.kt

private fun sharedFocus() {

        binding.otp1.addTextChangedListener(object : TextWatcher {
            override fun onTextChanged(s: CharSequence, start: Int, before: Int, count: Int) {
                if (sb.isEmpty() && binding.otp1.length() == 1) {
                    sb.append(s)
                    binding.otp1.clearFocus()
                    binding.otp2.requestFocus()
                }
            }

            override fun beforeTextChanged(
                s: CharSequence, start: Int, count: Int,
                after: Int
            ) {
                if (sb.length == 1) {
                    sb.deleteCharAt(0)
                }
            }

            override fun afterTextChanged(s: Editable) {
                if (sb.isEmpty()) {
                    binding.otp1.requestFocus()
                }
            }
        })

        binding.otp2.addTextChangedListener(object : TextWatcher {
            override fun onTextChanged(s: CharSequence, start: Int, before: Int, count: Int) {
                if (sb.isNotEmpty() && binding.otp2.length() == 1) {
                    sb.append(s)
                    binding.otp2.clearFocus()
                    binding.otp3.requestFocus()
                }
            }

            override fun beforeTextChanged(
                s: CharSequence, start: Int, count: Int,
                after: Int
            ) {
                if (sb.length == 2) {
                    sb.deleteCharAt(0)
                }
            }

            override fun afterTextChanged(s: Editable) {
                if (sb.isEmpty()) {
                    binding.otp1.requestFocus()
                }
            }
        })

        binding.otp3.addTextChangedListener(object : TextWatcher {
            override fun onTextChanged(s: CharSequence, start: Int, before: Int, count: Int) {
                if (sb.isNotEmpty() && binding.otp3.length() == 1) {
                    sb.append(s)
                    binding.otp3.clearFocus()
                    binding.otp4.requestFocus()
                }
            }

            override fun beforeTextChanged(
                s: CharSequence, start: Int, count: Int,
                after: Int
            ) {
                if (sb.length == 3) {
                    sb.deleteCharAt(0)
                }
            }

            override fun afterTextChanged(s: Editable) {
                if (sb.isEmpty()) {
                    binding.otp1.requestFocus()
                }
            }
        })

        binding.otp4.addTextChangedListener(object : TextWatcher {
            override fun onTextChanged(s: CharSequence, start: Int, before: Int, count: Int) {
                if (sb.isNotEmpty() && binding.otp4.length() == 1) {
                    sb.append(s)
                    binding.otp4.clearFocus()
                    binding.otp5.requestFocus()
                }
            }

            override fun beforeTextChanged(
                s: CharSequence, start: Int, count: Int,
                after: Int
            ) {
                if (sb.length == 4) {
                    sb.deleteCharAt(0)
                }
            }

            override fun afterTextChanged(s: Editable) {
                if (sb.isEmpty()) {
                    binding.otp1.requestFocus()
                }
            }
        })

        binding.otp5.addTextChangedListener(object : TextWatcher {
            override fun onTextChanged(s: CharSequence, start: Int, before: Int, count: Int) {
                if (sb.isNotEmpty() && binding.otp5.length() == 1) {
                    sb.append(s)
                    binding.otp5.clearFocus()
                    binding.otp6.requestFocus()
                }
            }

            override fun beforeTextChanged(
                s: CharSequence, start: Int, count: Int,
                after: Int
            ) {
                if (sb.length == 5) {
                    sb.deleteCharAt(0)
                }
            }

            override fun afterTextChanged(s: Editable) {
                if (sb.isEmpty()) {
                    binding.otp1.requestFocus()
                }
            }
        })

        binding.otp6.addTextChangedListener(object : TextWatcher {
            override fun onTextChanged(s: CharSequence, start: Int, before: Int, count: Int) {
                if (sb.isNotEmpty() && binding.otp6.length() == 1) {
                    sb.append(s)
                    binding.otp6.clearFocus()
                }
            }

            override fun beforeTextChanged(
                s: CharSequence, start: Int, count: Int,
                after: Int
            ) {
                if (sb.length == 6) {
                    sb.deleteCharAt(0)
                }
            }

            override fun afterTextChanged(s: Editable) {

                if (sb.isEmpty()) {
                    binding.otp1.requestFocus()
                }

                if (sb.length == 6) {
                    binding.otp6.clearFocus()
                    hideSoftKeyboard()
                    binding.submitButton.requestFocus()
                }
            }
        })
    }

TextWatcher.kt

/**
     *  A TextWatcher object
     */
    private val mTextWatcher: TextWatcher = object : TextWatcher {
        override fun beforeTextChanged(charSequence: CharSequence, i: Int, i2: Int, i3: Int) {}
        override fun onTextChanged(charSequence: CharSequence, i: Int, i2: Int, i3: Int) {}
        override fun afterTextChanged(editable: Editable) {
            // check Fields For Empty Values
            checkFieldsForEmptyValues()
        }
    }