57. Default Values for Parameters

One or more parameters can be defined with a default value. This can be really useful if most calls to the method will use the defaults:

def displayMessage (message,
                    title = 'Important message:',
                    border = true) {

    def borderText = ''

    if (border) {
        borderText = '--------------------------'
    }

    println """\
	    $borderText
	    $title
	    \t $message
	    $borderText
	    """
}

displayMessage 'Preparing to shut down. Please save your work'

The displayMethod can be called in a number of ways:

• displayMessage 'Preparing to shut down. Please save your work'
• displayMessage 'The system appears to have crashed', 'Error!'
• displayMessage 'Be prepared for the happiness patrol', 'Public announcement:', false

When you get to method overloading and other object-oriented concepts you’ll see that default parameter values can aid in reducing the variations of a method that you might need to provide.