Leanpub: Publish Early, Publish Often

53. Methods and Exceptions

The code in this chapter is rather skewed as we’d rarely throw an exception and catch it within the same try-catch block. Rather, we’re most likely to throw an exception from a method back to the caller and we use try blocks to catch exceptions from methods we’re calling.

Throwing an exception from a method results in no return value being returned to the caller - the caller needs to handle the exception. It’s important to note that, where the try and/or catch block contain a return statement, the finally block will be evaluated before the return is actually processed. In the next two examples below, the println in the finally block will always display.

Using return in catch

def testMethod() {
    try {
        10 / 0
    } catch (any) {
        return
    } finally {
        println 'Finally block has been evaluated'
    }
}

Using return in try

def testMethod() {
    try {
        return 100
    } catch (any) {
        println 'Exception'
    } finally {
        println 'Finally block has been evaluated'
    }
}

testMethod()

We’re about to get to the section on Methods.