header

Looping and FizzBuzz

Definying a range

def range = ('a'..'z')
print range

output: [a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z]

Iterate over a range of numbers:

def message = ''

(1..5).each{
  message += 'HI '
}

assert message == 'HI HI HI HI HI '

The for loop in Groovy is much simpler in collections.

["A","B","C"].each{                      // 1
  println it
}

def map = ['one':1, 'two':2, 'three':3]

map.each { key, value ->                 // 2
  println "$key : $value"
}

map.'four' = 4                          // 3

assert map['one'] == 1                  // 4

def text = "abc"
def list = []
for (c in text) {                       // 5
    list.add(c)
}
assert list == ["a", "b", "c"]
  1. Iterate over a list
  2. Iterate over a map
  3. Adding a new value to the map
  4. Getting an element from a map
  5. Iterate over the characters in a string

Groovy supports the usual while

def x = 0
def y = 5

while ( y-- > 0 ) {
    x++
}

assert x == 5

Example: Count letters from all Strings in a list

def list = ['Java', 'Groovy', 'Grails']

Integer count = 0
list.each {
  if(it.class.name == "java.lang.String"){
    return count += it.size()
  }
}

assert count == 16

Example: Same that the last example but using collect

def list = ['Java', 'Groovy', 'Grails']

Integer count = list.collect {
  if(it.class.name == "java.lang.String"){
    it.size()
  }
}.sum()

assert count == 16

Note: Use collect when you need to operate over all elements in a list

FizzBuzz in Groovy

Fizz buzz is a group word game for children to teach them about division. Players take turns to count incrementally, replacing any number divisible by three with the word “fizz”, and any number divisible by five with the word “buzz”.

Our final example is to test a starting round of fizz buzz from 1 to 100 as follow:

1, 2, Fizz, 4, Buzz, Fizz, 7, 8, Fizz, Buzz, 11, Fizz, 13, 14 FizzBuzz…

(1..100).each{
  println "${it%3 ?'':'Fizz'}${it%5 ?'':'Buzz'}" ?: it
}

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