Retrieve Index of a an Element in an Array of Arrays in Groovy

Question

I have an array of arrays.

def my_array = [[null], [10382], [11901], [null], [10386], [10385], [11901], [10386], [11901], [10386], [3], [null], [10504], [3]]

I want to find the index of the FIRST occurrence of an element, for example [3].

I am using findIndexOf.

 def index = my_array.findIndexOf { it == [3] }

However, this returns -1. I think this is the index of the element in array [3] not in array my_array. How do I get the index of the element [3] in the my_array?

Matias Bjarland · Accepted Answer · 2019-05-24 14:38:32Z

4

Running this code:

def my_array = [[null],  // index  0
                [10382], // index  1
                [11901], // index  2
                [null],  // index  3
                [10386], // index  4
                [10385], // index  5
                [11901], // index  6
                [10386], // index  7
                [11901], // index  8
                [10386], // index  9
                [3],     // index 10
                [null],  // index 11
                [10504], // index 12
                [3]]     // index 13

def index = my_array.findIndexOf { it == [3] }
println "index: $index"

which is identical to your code results in:

~> groovy solution.groovy 
index: 10

~>

on java 8 and groovy 2.1.16. In other words, your code should work.

As a side note, do you really need a list of lists? As all the lists are of length one you might as well just have a list of elements directly.

answered May 24, 2019 at 14:38

Matias Bjarland

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2 Comments

SSF Over a year ago

Thanks. I m using the Jenkins Groovy engine. There could be some differences in the dependencies. To answer your question. I don't really need it. Can I easily convert list of list into a list instead without being expensive?

Matias Bjarland Over a year ago

list.flatten() should do it.

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