Groovy - Loops: For, While, Each

7. Loops: For, While, Each

Loops in programming are used to execute a block of code repeatedly. In Groovy, you can use 'for', 'while', and 'each' loops for various iteration tasks.

1. For Loops:

For loops are used when you know in advance how many times you want to execute a block of code. Groovy provides a concise way to write for loops using the 'in' keyword.

for (element in collection) {
    // Code to execute for each element in the collection
}

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

for (num in numbers) {
    println("Number: ${num}")
}

In this example, the for loop iterates through each element in the 'numbers' list and prints them.

2. While Loops:

While loops are used when you want to execute a block of code repeatedly as long as a specified condition is true.

while (condition) {
    // Code to execute as long as the condition is true
}

def count = 1

while (count <= 5) {
    println("Count: ${count}")
    count++
}

In this example, the while loop prints the value of  'count' as long as it is less than or equal to 5.

3. Each Loops:

Each loops are used to iterate over collections, such as lists and maps, in a concise way. Groovy provides a built-in 'each' method for this purpose.

collection.each { element ->
    // Code to execute for each element in the collection
}

map.each { key, value ->
    // Code to execute for each key-value pair in the map
}

def colors = ['red', 'green', 'blue']

colors.each { color ->
    println("Color: ${color}")
}

In this example, the 'each' loop iterates through each element in the 'colors'list and prints them.

def person = [name: 'John', age: 25]

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

In this example, the 'each' loop iterates through each key-value pair in the 'person' map and prints them.

Break and Continue:

You can use the 'break' statement to exit a loop prematurely and the 'continue' statement to skip the current iteration and proceed to the next one.

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

for (num in numbers) {
    if (num == 3) {
        break
    }
    println("Number: ${num}")
}

In this example, the loop will break when it encounters the value 3, and no further iterations will occur.

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

for (num in numbers) {
    if (num == 3) {
        continue
    }
    println("Number: ${num}")
}