Groovy pop push

In Groovy you can use an array as if it was a stack pushing elements to the end and poping elements from the end.

names = []

names.push('Mary')
names.push('Joe')
names.push('Fanny')
names.push('George')
names.push('Liz')
names.push('Peter')

println(names)

first = names.pop()
println(first)
println(names)

[Mary, Joe, Fanny, George, Liz, Peter]
Peter
[Mary, Joe, Fanny, George, Liz]

Pop from empty array raises exception

names = []
names.pop()

Caught: java.util.NoSuchElementException: Cannot pop() an empty List
java.util.NoSuchElementException: Cannot pop() an empty List
	at pop_empty.run(pop_empty.groovy:2)

Check emptyness before calling pop

To avoid the exception we can check the size of the array before calling pop.

names = []

if (names.size()) {
    println(names.pop())
}

timestamp: 2019-04-20T07:30:01 tags:

• pop
• push
• size