Java How to Convert List to Array with Example

In Java, convert a List to an array by calling list.toArray(new Type[0]) or list.toArray(new Type[list.size()]), where Type is the array element type.

Examples

Input["apple", "banana", "cherry"]

Output["apple", "banana", "cherry"]

Input[]

Output[]

Input[1, 2, 3, 4]

Output[1, 2, 3, 4]

How to Think About It

To convert a List to an array, you create a new array of the same type and size as the List, then use the List's toArray method to fill this array with the List's elements. This ensures the array has the correct type and length.

Algorithm

1

Get the List you want to convert.

2

Create a new array of the desired type with the same size as the List.

3

Call the List's toArray method, passing the new array as an argument.

4

The method fills the array with List elements and returns it.

5

Use or return the filled array.

Code

java

import java.util.*;

public class ListToArrayExample {
    public static void main(String[] args) {
        List<String> fruits = Arrays.asList("apple", "banana", "cherry");
        String[] fruitsArray = fruits.toArray(new String[fruits.size()]);
        System.out.println(java.util.Arrays.toString(fruitsArray));
    }
}

Output

[apple, banana, cherry]

Dry Run

Let's trace converting List ["apple", "banana", "cherry"] to array.

1

Create List

List fruits = ["apple", "banana", "cherry"]

2

Create Array

String[] fruitsArray = new String[3]

3

Call toArray

fruits.toArray(fruitsArray) fills fruitsArray with ["apple", "banana", "cherry"]

Step	Array Content
After Step 2	[null, null, null]
After Step 3	[apple, banana, cherry]

Why This Works

Step 1: Create Array of Correct Size

You create a new array with the same size as the List to hold all elements.

Step 2: Use toArray Method

The List's toArray method copies elements into the new array.

Step 3: Return Filled Array

The method returns the array filled with List elements, ready to use.

Alternative Approaches

Using toArray() without argument

java

import java.util.*;

public class ListToArrayAlt {
    public static void main(String[] args) {
        List<String> fruits = Arrays.asList("apple", "banana", "cherry");
        Object[] fruitsArray = fruits.toArray();
        System.out.println(java.util.Arrays.toString(fruitsArray));
    }
}

Returns an Object array, so you may need to cast elements; less type-safe.

Using Stream API

java

import java.util.*;

public class ListToArrayStream {
    public static void main(String[] args) {
        List<String> fruits = Arrays.asList("apple", "banana", "cherry");
        String[] fruitsArray = fruits.stream().toArray(String[]::new);
        System.out.println(java.util.Arrays.toString(fruitsArray));
    }
}

Uses streams, more flexible but slightly more complex.

Complexity: O(n) time, O(n) space

Time Complexity

The method copies each element once, so time grows linearly with the List size.

Space Complexity

A new array of the same size as the List is created, so space grows linearly.

Which Approach is Fastest?

Using toArray(new Type[size]) is fastest and type-safe; using streams adds overhead.

Approach	Time	Space	Best For
toArray(new Type[size])	O(n)	O(n)	Type-safe, efficient conversion
toArray()	O(n)	O(n)	Quick but returns Object[], less type-safe
Stream API	O(n)	O(n)	Flexible, functional style, slight overhead