Multidimensional array of Objects in Kotlin

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I'm new in Kotlin, and I want to create a multi dimensional array of a custom class, with null permitted. Something like that

private var array_map = arrayOf<Array<Obstacle?>>()

...

array_map[1][2] = Obstacle()

How can I do it? Thank you!

You can use private var arrayMap: Array<Array<Obstacle?>> = arrayOf(). Just wrap with as much Array<> as you need.

Lesson 10 - Multidimensional arrays in Kotlin, This tutorial goes over 2d arrays and multidimensional arrays in general. use objects properly, use 2D arrays to store multiple sets of data of a single entity. Multidimensional array of Objects in Kotlin. and I want to create a multi dimensional array of a custom class, A 2D array of the Obstacle object would be as

In case you need the index of each element in the constructor of the elements of the array:

Declaration:

var matrix: Array<Array<Obstacle?>>

Instantiation and initialization:

matrix = Array(numRows) { row ->
            Array(numCols) { col ->
                Obstacle(row, col)
            }
         }

Multi-dimensonal arrays are a pain point in Kotlin, The simplest use case is a 2d array to represent a grid for a tile based game. It is not a big deal, but everything else about Kotlin is so nice this  There are two ways to define an array in Kotlin. Using the arrayOf () function –. We can use the library function arrayOf () to create an array by passing the values of the elements to the function. Syntax: val num = arrayOf (1, 2, 3, 4) //implicit type declaration val num = arrayOf<Int> (1, 2, 3) //explicit type declaration.

Not sure if this is what you want, but imagine that Obstacle is a custom class with a field num as below

data class Obstacle(var num: Int){}

A 2D array of the Obstacle object would be as below:

val array: Array<Obstacle?> = arrayOf(Obstacle(123), Obstacle(234))
val arrayOfArray: Array<Array<Obstacle?>> = arrayOf(array)
println(arrayOfArray[0][0]) // would print Obstacle(num=123)
println(arrayOfArray[0][1]) // would print Obstacle(num=234)

So you should be declaring your 2D array as below

val arrayOfArray: Array<Array<Obstacle?>> = arrayOf()

How to create a 2D array in Kotlin, Since Kotlin brings new syntax, let's see how to work with a 2D array in Kotlin. We have initialized the Array object by passing the size and initializer: Copy. Kotlin Program to Add Two Matrix Using Multi-dimensional Arrays Kotlin Program to Add Two Matrix Using Multi-dimensional Arrays In this program, you'll learn to add two matrices using multi-dimensional arrays in Kotlin. Example: Program to Add Two Matrices

Your code will compile as is. The problem is just that array size can't be changed and arrayOf<Array<Obstacle?>>() creates an empty array, so array_map[1][2] = Obstacle() fails at runtime. (Unless you do array_map = ... somewhere between them. Note that you should prefer val arrayMap, which can't be reassigned, unless you have a specific reason to use var.)

If you want your array to start with nulls, there is arrayOfNulls in the standard library, but it only creates a single-dimensional array, and what you really need is an array of arrays of nulls. You can write a helper function:

inline fun <reified T> matrixOfNulls(n: Int, m: Int) = Array(n) { arrayOfNulls<T>(m) }

private val arrayMap = matrixOfNulls<Obstacle>(5, 5) // example arguments

The Programmers Guide To Kotlin, Arrays in Kotlin are based on Java's array object, but the Creating multidimensional arrays is implemented in the same way as in most other  Check out this quick post to learn more about Kotlin primitive and object arrays, offering a new take and some much-needed clarity on the subject.

The approach I always use for this case is:

arr2D = Array(sizeA) { Array(sizeB) { content } } 

Note I replaced the sizes by fields names to illustrate that each number/field represents the width and height length of each dimension of the 2D array.

Also, content should be replaced by the main content you want to fill in each coordinate, in your case seems you aims to setup with Obstacle() instances. If you want fill this content in other moment put null or a quick Any() reference.

In this last case, after creating that you can simply perform to set the itens:

arr2D[1][2] = Obstacle() 

Kotlin Program to Add Two Matrix Using Multi-dimensional Arrays, In this program, you'll learn to add two matrices using multi-dimensional arrays in Kotlin. val array = Array(n, {IntArray(n)}) Here, n represents the dimension of the array. Here, we have used the Array class of Kotlin, which represents an array (specifically, a Java array when targeting the JVM platform).

Kotlin arrays tutorial - working with arrays in Kotlin, Kotlin arrays tutorial shows how to work with arrays in Kotlin. Kotlin arrays are created with functions such as arrayOf() or intArrayOf() , or The example creates a two-dimensional array by nesting intArrayOf() function calls  Kotlin Array. Array is collection of similar data types either of Int, String etc. Array in Kotlinis mutable in nature with fixed size which means we can perform both read and write operations on elements of array. Constructor of array: Array constructor is declared with specified size and init function. The init function is used to returns the elements of array with their index.

Arrays in Kotlin, Kotlin array is an object the contains elements of similar data type. Two-​dimensional array(2-D): it's an array containing multiple arrays within it, where all of  I want to create an Array of objects with a specific number of elements in Kotlin, the problem is I don't now the current values for initialization of every object in the declaration, I tried: var miArreglo = Array<Medico>(20, {null}) in Java, I have this and is exactly what I want, but i need it in Kotlin.

how do you even print a 2d array in kotlin?? : Kotlin, how do you even print a 2d array in kotlin?? I have a method that takes a MutableList of objects and needs return a MutableList of the same objects but with  Kotlin arrays are created with functions such as arrayOf() or intArrayOf(), or with classes such as IntArray or FloatArray.. Kotlin array initialization. In the first example, we show how we can initialize arrays in Kotlin.

Comments
  • honestly, this clarifies so much that this snippet should go directly to kotlinlang.org/docs ))