Sealed class representing all the possible UI states

UIState.kt

/**
 * Represents the UI state of a long running operation.
 */
sealed class UIState<out Int> {
    /**
     * Indicates the operation succeeded.
     */
    object Success : UIState<Nothing>()

    /**
     * Indicates the operation is going on with a loading message ID.
     *
     * @param loadingMessageId The ID to find the string resource.
     */
    class Loading(@StringRes val loadingMessageId: Int) : UIState<Int>()

    /**
     * Indicates the operation failed with an error message ID.
     *
     * @param errorMessageId The ID to find the string resource.
     */
    class Error(@StringRes val errorMessageId: Int) : UIState<Int>()
}