June 22, 2016

Groovy Goodness: Turn A Map Or List As String To Map Or List

In a previous post we learned how to use the toListString or toMapString methods. With these methods we create a String representation of a List or Map object. With a bit of Groovy code we can take such a String object and turn it into a List or Map again.

In the following code snippet we turn the String value [abc, 123, Groovy rocks!] to a List with three items:

// Original List with three items.
def original = ['abc', 123, 'Groovy rocks!']

// Create a String representation:
// [abc, 123, Groovy rocks!]
def listAsString = original.toListString()

// Take the String value between
// the [ and ] brackets, then
// split on , to create a List
// with values.
def list = listAsString[1..-2].split(', ')

assert list.size() == 3
assert list[0] == 'abc'
assert list[1] == '123' // String value
assert list[2] == 'Groovy rocks!'

We can do something similar for a String value representing a map structure:

// Original Map structure.
def original = [name: 'mrhaki', age: 42]

// Turn map into String representation:
// [name:mrhaki, age:42]
def mapAsString = original.toMapString()

def map = 
    // Take the String value between
    // the [ and ] brackets.
        // Split on , to get a List.
        .split(', ')
        // Each list item is transformed
        // to a Map entry with key/value.
        .collectEntries { entry -> 
            def pair = entry.split(':')
            [(pair.first()): pair.last()]

assert map.size() == 2
assert map.name == 'mrhaki'
assert map.age == '42'

Written with Groovy 2.4.7.