'How to create an empty array in kotlin?

I'm using Array(0, {i -> ""}) currently, and I would like to know if there's a better implementation such as Array()

plus, if I'm using arrayOfNulls<String>(0) as Array<String>, the compiler will alert me that this cast can never succeed. But it's the default implementation inside Array(0, {i -> ""}). Do I miss something?

arrayskotlin


Solution 1:[1]

As of late (June 2015) there is the Kotlin standard library function

public fun <T> arrayOf(vararg t: T): Array<T>

So to create an empty array of Strings you can write

val emptyStringArray = arrayOf<String>()

Solution 2:[2]

Just for reference, there is also emptyArray. For example,

var arr = emptyArray<String>()

See

Solution 3:[3]

Empty or null? That's the question!

To create an array of nulls, simply use arrayOfNulls<Type>(length).

But to generate an EMPTY array of size length, use:

val arr = Array(length) { emptyObject }

Note that you must define an emptyObject properly per each data-type (beacause you don't want nulls). E. g. for Strings, emptyObject can be "". So:

val arr = Array(3) { "" }  // is equivalent for: arrayOf("","","")

Here is a live example. Note that the program runs with two sample arguments, by default.

Solution 4:[4]

null array 

var arrayString=Array<String?>(5){null}
var nullArray= arrayOfNulls<String>(5)

Solution 5:[5]

As mentioned above, you can use IntArray(size) or FloatArray(size).

Solution 6:[6]

I found two ways to create an empty array, the second way without a lambda:

var arr = Array (0, { i -> "" })
var arr2 = array<String>()

Regarding Kotlin's null strings, this is not allowed. You have to use String? type to allow strings to be null.

Solution 7:[7]

Use:

@JvmField val EMPTY_STRING_ARRAY = arrayOfNulls<String>(0)

It returns an 0 size array of Strings, initialized with null values.

1. Wrong:

@JvmField val EMPTY_STRING_ARRAY = emptyArray<String>()

It returns arrayOfNulls<String>(0)

2. Wrong:

 @JvmField val EMPTY_STRING_ARRAY = arrayOf<String>()

It returns an array containing the Strings.

Solution 8:[8]

Simplest way to initialise array and assigning values :

val myArray: Array<String> = Array(2) { "" }
    myArray[0] = "Java"
    myArray[1] = "Kotlin"

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source
Solution 1 Martian Odyssey
Solution 2
Solution 3
Solution 4 Ali Hasan
Solution 5 CoolMind
Solution 6 tbruyelle
Solution 7 Alexander Savin
Solution 8 Prashant Singh

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