如何正确检查 Spring EL 表达式中的 Boolean 值？

Question

I'm a bit new to using Spring Expression Language but I'm trying to see what is the best way to check a that a Boolean value is not null and true?

For type "Display" there is a property "removeMessage" which is of type java.lang.Boolean . So I want to first check that this value is not null and that it is true. Based on if this is true or not I will either return an empty string or a calculatedMessage.

I am currently checking with below expression:

display?.removeMessage != null && display?.removeMessage ? '' : display.calculatedMessage

While this works, I was hoping to find a more nicer way to do the null and true check. I was thinking/hoping for something more like how we would check normally such as eg BoolenUtils.isTrue(value) (apache), or even just checking like Boolean.TRUE.equals(value) which takes care of the null check.

Answer 1

Just having this should work, and already include your null check:

display?.removeMessage ? null : display.calculatedMessage