Concisely operating with ternaries
One of my favorite features in Groovy is its hip ? operator, which facilitates Nullpointer navigation safety– while this feature isn’t available directly in Java, there is a handy Java operator that I’ve found myself using more and more these days (in Java, man) based upon my dynamic language conditioning of preferring code terseness: the ternary operator.
The ternary operator doesn’t directly relate to the ? operator in Groovy; however, its bag is similar– that is, reducing typing. This operator enables you to succinctly assign a value to a variable based on one or more boolean decisions like so:
this.location = (location != null ? location : DEFAULT_LOC_NAME);In the code above, the location member variable (this.location) is being set to a location local variable or a static constant (DEFAULT_LOC_NAME) if the location local variable is null. Thus, the code to the left of the ? operator must be a boolean expression and the value to the left of the : operator is returned if true and the value to the right of the : is returned if the expression is false.
The single line of Java code facilitated by the ternary would be roughly equivalent to a conditional like so:
if(location != null){
this.location = location;
}else{
this.location = DEFAULT_LOC_NAME;
}Of course, the {}’s are optional (thus, the code could be reduced somewhat); however, the point being that a copasetically placed ternary reduces typing and a bit of redundancy (in this case), baby.
In the past, I used to eschew the ternary due to its terseness– I found myself using conditionals to more clearly express my intent; however, after years of dynamic language conditioning, I’ve found myself reserving my stance on the ternary.
If you find yourself typing too much Java, baby, then consider employing the ternary– you may find its laconic nature refreshingly simple. Can you dig it, man?
Saturday 17 May 2008 | Andy | Groovy, Software Development
Don’t forget about the “?:” Elvis operator (does it get any groovier than Elvis?). It’s essentially a shortened form of the ternary operator where if the first value evaluates to false, the expression will evaluate to the item after the operator.
So in the example you gave above, it can be reduced even further to:
this.location = location ?: DEFAULT_LOC_NAME
If “location” is null, this.location will be set to DEFAULT_LOC_NAME, otherwise, if location is not null this.location will be set to location’s value.
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Sorry to burst your bubble, but Java has this operator too. Not sure how long though.
[code]
public class TernaryDemo{
public static void main(String[] args){
String location = null;
String ternaryLocation = location == null? “DefaultLocation”: location;
System.out.println(”Ternary selected location is: ” + ternaryLocation);
}
}
[/code]
java TernaryDemo
Ternary selected location is: DefaultLocation
~ Grundlefleck
Yes, I’m a moron who skim reads. Ignore.
Ted- thanks for the example of the Elvis operator– indeed, quite Groovy, man. If writing ternary style logic in Groovy, it’s a total win!