# Showing buttons based on a message received by arduino

**URL:** https://discourse.processing.org/t/showing-buttons-based-on-a-message-received-by-arduino/22235
**Category:** Electronics (Arduino, etc.)
**Created:** [June 29, 2020, 4:33am UTC](https://discourse.processing.org/t/showing-buttons-based-on-a-message-received-by-arduino/22235 "2020-06-29T04:33:58Z")
**Posts on this page:** 1
**Showing post:** 5

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### Author: ![GoToLoop](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/gotoloop/32/86_2.png) [@GoToLoop](https://discourse.processing.org/u/GoToLoop)
#### Post date: [June 29, 2020, 11:06am UTC](https://discourse.processing.org/t/showing-buttons-based-on-a-message-received-by-arduino/22235/5 "2020-06-29T11:06:54Z")

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> [@josephh](#):
>
> `received = message.equals("ack_on");`

Although it’s clearer it is unsafe, b/c if it happens _message_ is `null` it’s gonna `throw` an NPE error: ⚠  
[Docs.Oracle.com/en/java/javase/11/docs/api/java.base/java/lang/NullPointerException.html](http://Docs.Oracle.com/en/java/javase/11/docs/api/java.base/java/lang/NullPointerException.html)

While `received = "ack_on".equals(message);` is Exception-free b/c a literal String is never `null` & method **equals()** accepts a passed `null` argument: 😉

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