In Groovy, the keyword null is used to represent the absence of a value or non-existence of an object. The keywords true and false are used to represent boolean values.
Here are some examples of how to check whether a value is null, true, or false in Groovy:
Checking if a value is null:
def myValue = null
if (myValue == null) {
println("The value is null.")
} else {
println("The value is not null.")
}
Checking if a value is true:
def myValue = true
if (myValue) {
println("The value is true.")
} else {
println("The value is not true.")
}
Checking if a value is false:
def myValue = false
if (!myValue) {
println("The value is false.")
} else {
println("The value is not false.")
}
Note that in the last example, we used the negation operator (!) to check if the value is false. This is because false is considered a "falsy" value in Groovy, so just checking if (myValue) would not give the desired result.