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How to Append A List Of Lists In Groovy?

3 minutes read

To append a list of lists in Groovy, you can use the addAll() method to add all the elements from each list in the list of lists to a new list. Here is an example code snippet to illustrate this:

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def listOfLists = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
def appendedList = []

listOfLists.each{ sublist ->
   appendedList.addAll(sublist)
}

println(appendedList)


In this example, the listOfLists variable contains three lists of integers. We iterate over each list using the each method, and then use the addAll() method to add all the elements from each sublist to the appendedList list. Finally, we print the appendedList to display the combined list of elements from all the sublists.


How do you merge nested arrays in Groovy?

In Groovy, you can merge nested arrays using the flatten() method along with the spread operator * within a collect or inject method. Here's an example:

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def nestedArrays = [[1, 2], [3, 4], [5, 6]]

def mergedArray = nestedArrays.collectMany { it.flatten() }

println mergedArray // Output: [1, 2, 3, 4, 5, 6]


In this example, the collectMany method is used to iterate over each nested array in nestedArrays, and flatten() method is used to flatten each nested array into a single dimensional array. Finally, all the flattened arrays are collected into a single array mergedArray.


What is the Groovy syntax for combining string lists?

To combine string lists in Groovy, you can use the "+" operator.


For example:

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def list1 = ["apple", "banana"]
def list2 = ["cherry", "orange"]

def combinedList = list1 + list2

println combinedList


This will output:

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[apple, banana, cherry, orange]



What is the Groovy syntax for combining multiple lists of lists?

To combine multiple lists of lists in Groovy, you can use the flatten() method. Here is an example of the syntax to combine two lists of lists:

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List<List<Integer>> list1 = [[1, 2], [3, 4]];
List<List<Integer>> list2 = [[5, 6], [7, 8]];

List<List<Integer>> combinedList = [list1, list2].flatten();

println(combinedList);


In this example, the flatten() method is used to flatten the list of lists into a single list. The output will be [1, 2, 3, 4, 5, 6, 7, 8].


What is the recommended way to join distinct lists in Groovy?

One recommended way to join distinct lists in Groovy is to use the plus operator (+) to concatenate the lists and then use the unique() method to remove duplicates. Here is an example:

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def list1 = [1, 2, 3]
def list2 = [3, 4, 5]

def joinedList = (list1 + list2).unique()

println joinedList


This code will output:

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[1, 2, 3, 4, 5]


It combines the elements of both list1 and list2, removes duplicates, and creates a new list with distinct values.


How to append sub-lists to a main list in Groovy?

In Groovy, you can append sub-lists to a main list using the addAll() method. Here's an example:

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def mainList = [1, 2, 3]
def subList1 = [4, 5, 6]
def subList2 = [7, 8, 9]

mainList.addAll(subList1)
mainList.addAll(subList2)

println mainList


Output:

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[1, 2, 3, 4, 5, 6, 7, 8, 9]


In this example, we first declare a main list (mainList) and two sub-lists (subList1 and subList2). We then use the addAll() method to append the elements of subList1 and subList2 to the mainList. Finally, we print out the mainList to see the result.


What is the best approach to merge lists of lists in Groovy?

One of the best approaches to merge lists of lists in Groovy is to use the flatten method. This method flattens a collection of lists into a single list. Here's an example:

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List<List<Integer>> listOfLists = [[1, 2], [3, 4], [5, 6]];
List<Integer> mergedList = listOfLists.flatten();
println mergedList;


This will output:

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[1, 2, 3, 4, 5, 6]


You can also use the addAll method to merge lists of lists manually:

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List<List<Integer>> listOfLists = [[1, 2], [3, 4], [5, 6]];
List<Integer> mergedList = [];
listOfLists.each { subList ->
    mergedList.addAll(subList);
}
println mergedList;


Both of these approaches will merge lists of lists effectively in Groovy.

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