Lists, Maps and Ranges

Groovy Lists

Groovy provides enhanced list handling with the def keyword and a rich API for collection manipulation:

// Create lists
def fruits = ["apple", "banana", "cherry"]
def numbers = [1, 2, 3, 4, 5]

// Access elements
println fruits[0]       // apple
println fruits.last()   // cherry

// Add and remove
fruits << "date"        // Append
def top3 = fruits.take(3)

List Operations

Groovy lists support functional operations out of the box:

def nums = [1, 2, 3, 4, 5]

def doubled = nums.collect { it * 2 }
// [2, 4, 6, 8, 10]

def evens = nums.findAll { it % 2 == 0 }
// [2, 4]

def sum = nums.sum()
// 15

nums.each { println it }

Maps

Maps in Groovy use a simple syntax and support dot-notation access:

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

println person.name    // Alice
println person["age"]  // 30

person << [email: "alice@example.com"]

Ranges

Ranges create sequences of values and are useful for iteration and slicing:

def oneToTen = 1..10
println oneToTen.collect { it * it }
// [1, 4, 9, 16, 25, 36, 49, 64, 81, 100]

// String ranges
def letters = "a".."f"
println letters.toList()
// [a, b, c, d, e, f]

Key Points

• Groovy lists use square bracket syntax and support rich operations.
• collect, findAll, and each are powerful iteration methods.
• Maps use colon syntax and support dot-notation access.
• Ranges create sequences with .. operator.
• The << operator appends to lists and maps.