Groovy - Lists and Maps

9. Lists and Maps

Lists and maps are two fundamental data structures in Groovy for organizing and manipulating data. Lists are collections of ordered elements, and maps are collections of key-value pairs.

Lists:

A list in Groovy is an ordered collection of elements. Lists can contain elements of various data types, including numbers, strings, and even other lists.

Creating Lists:

You can create a list in Groovy using square brackets '[]' and separating the elements with commas.

def fruits = ["apple", "banana", "cherry"]

def firstFruit = fruits[0]
def secondFruit = fruits[1]

In this example, we accessed the first and second elements of the 'fruits'list.

Modifying Lists:

Lists are mutable, meaning you can add, remove, or change elements.

fruits.add("orange") // Adds "orange" to the end of the list
fruits.remove(1) // Removes the second element ("banana")
fruits[0] = "kiwi" // Changes the first element to "kiwi"

Iterating Over Lists:

You can iterate over a list using loops or the 'each'method.

for (fruit in fruits) {
    println(fruit)
}

fruits.each { fruit ->
    println(fruit)
}

def person = [name: "Alice", age: 30, city: "New York"]

def name = person.name
def age = person["age"]

In this example, we accessed the 'name' and 'age' values from the 'person' map.

Modifying Maps:

Maps are mutable, so you can add, remove, or update key-value pairs.

person["city"] = "San Francisco" // Updates the value for the "city" key
person.job = "Engineer" // Adds a new key-value pair
person.remove("age") // Removes the "age" key and its value

Iterating Over Maps:

You can iterate over the keys or key-value pairs of a map using loops or the 'each' method.

for (key in person.keySet()) {
    println("$key: ${person[key]}")
}

person.each { key, value ->
    println("$key: $value")
}