If in a state where isValid() returns false, this function returns the error message. It is up to calling shouldShowError to determine if it should be displayed on screen.

isBlank

abstract fun isBlank(): Boolean

This is used to indicate the field is blank which can be helpful when ignoring optional fields.

isFull

open override fun isFull(): Boolean

This is used to indicate the field contains the maximum number of characters. This is needed to know when to advance to the next field.

isValid

open override fun isValid(): Boolean

Indicates an field is valid and field extraction can happen and be used to create PaymentMethod Parameters

shouldShowError

abstract fun shouldShowError(hasFocus: Boolean): Boolean

Indicate if this is an error that should be displayed to the user. This cannot be used to determine if the field is valid or not because there are some cases such as incomplete or blank where the error is not displayed, but also not valid.