allprojects {
		repositories {
			...
			maven { url 'https://jitpack.io' }
		}
	}

dependencies {
		implementation 'com.github.KucherenkoIhor:RxValidationTextInputLayout:0.1'
}

     <com.kucherenko.RxValidationTextInputLayout
                android:id="@+id/tilFirstName"
                style="@style/TextInputLayout.Counter"
                android:layout_marginTop="@dimen/margin_l"
                app:layout_constraintLeft_toLeftOf="parent"
                app:layout_constraintRight_toRightOf="parent"
                app:layout_constraintTop_toBottomOf="parent"
                app:help="at least 3 letters"
                app:error="@string/invalid_first_name"
                app:errorTextAppearance="@style/TextAppearance.AppCompat.Small.Error"
                app:helperTextAppearance="@style/TextAppearance.AppCompat.Small.Helper"
                app:regex="@string/regex_name">
    
                <android.support.design.widget.TextInputEditText
                    android:id="@+id/etFirstName"
                    style="@style/EditText.SingleLine"
                    android:hint="@string/hint_first_name"
                    android:imeOptions="actionNext"
                    android:inputType="textPersonName" />
    
            </com.kucherenko.RxValidationTextInputLayout>

 tilFirstName.onReady = { observable ->  
            disposable = observable.subscribe { isValid ->
                btnSignIn.isEnabled = isValid
            }
        }

tilFirstName.onReady = { observable ->
            disposable = observable.subscribe { isValid ->
                btnSignIn.isEnabled = isValid
            }
        }

val textInputLayouts = arrayOf(
                tilFirstName,
                tilLastName,
                tilEmail,
                tilPhone,
                tilYear,
                tilDob,
                tilPassword,
                tilConfirmPassword)

        RxValidationTextInputLayout.combineOnReady(*textInputLayouts) { observable ->
            disposable = observable.subscribe { btnSignIn.isEnabled = it }
        }