08 July 2019

Convert List to Array in Java

development

Converting between List and Array is a very common operation in Java.

The best and easiest way to convert a List into an Array in Java is to use the .toArray() method.

Likewise, we can convert back a List to Array using the Arrays.asList() method.

The examples below show how to convert List of String and List of Integers to their Array equivalents.

Convert List to Array of String

import java.util.ArrayList;
import java.util.List;

public class ConvertArrayListToArray {
    public static void main(String[] args) {
        List<String> itemList = new ArrayList<String>();
        itemList.add("item1");
        itemList.add("item2");
        itemList.add("item3");

        String[] itemsArray = new String[itemList.size()];
        itemsArray = itemList.toArray(itemsArray);

        for(String s : itemsArray)
            System.out.println(s);
    }
}

We can use the same approach to convert List of Integers to Array of Integers, for example:

Convert List to Array of Integers

import java.util.ArrayList;
import java.util.List;

public class ConvertArrayListToArray {
    public static void main(String[] args) {
        List<Integer> intList = new ArrayList<Integer>();
        intList.add(10);
        intList.add(20);
        intList.add(30);

        Integer[] intArray = new Integer[intList.size()];
        intArray = intList.toArray(intArray);

        for(Integer i : intArray)
            System.out.println(i);
    }
}

Convert String Array to List

You can also convert an Array back to a List. To do this, we use Arrays.asList(). For example:

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class ConvertArrayToList {
    public static void main(String[] args) {
        String[] stringArray = {"item 1", "item 2", "item 3", "item 4"};
        List<String> stringList = new ArrayList(Arrays.asList(stringArray));

        for (String listItem : stringList) {
            System.out.println(listItem);
        }
    }
}

08 July 2019