Groovy properties

I’m on a Groovy buzz at the moment. I figured that I’d learn the language properly rather than poking around, doing stuff in Grails. It’s one of Groovy’s huge advantages that you can hack away as a Java programmer and be fairly productive. So playing with properties:

class Thingo {
    def value
    def anotherValue

    void setValue(Integer value) {
        this.value = value * 2
    }
}

thingo = new Thingo(value: 3);
println thingo.value

thingo.value = 2
println thingo.value

thingo.anotherValue = 2
println thingo.anotherValue

The results:

6
4
2

A few things are going on here:

• When we construct our Thingo in the script above, Groovy calls the default constructor, and immediately updates value. As a setter method has been defined “setValue()”, Groovy does not generate a default one and uses what’s there -the one we’re using to encapsulate some programmer-defined variable fiddling.
• Likewise, when we assign a variable to value, Groovy makes use of our setter to update value.
• When we assign a number to anotherValue,  a default setter is created at runtime and is used to perform the update.

I’m really enjoying the benefit of the groovyConsole – it lets you mess around with code really easily, without needing to even save it. Low-ceremony programming at it’s best.

If you’re looking at learning Groovy properly, I strongly recommed Programming Groovy by Venkat Subramaniam. Just like the language itself, it gets you doing stuff very quickly.