How do I add multiple items to a Java ArrayList in single statement?

We can use Arrays.asList() method to add multiple items to a Java ArrayList in a single statement. This method returns a fixed-size list backed by the specified array, which we then pass to the ArrayList constructor to create a modifiable list.

Syntax

public static <T> List<T> asList(T... a)

Returns a fixed-size list backed by the specified array.

• T − The runtime type of the array.
• a − The array by which the list will be backed.

Note − The list returned by Arrays.asList() is fixed-size, meaning you cannot add or remove elements from it. To get a modifiable list, pass it to the ArrayList constructor.

Example

The following example shows how to create an ArrayList with multiple items in a single statement ?

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

public class CollectionsDemo {
    public static void main(String[] args) {
        // Create a modifiable list with multiple items in one statement
        List<String> list = new ArrayList<>(Arrays.asList("A", "B", "C"));

        System.out.println(list);

        // Since it's an ArrayList, we can add more items
        list.add("D");
        System.out.println(list);
    }
}

The output of the above code is ?

[A, B, C]
[A, B, C, D]

Conclusion

Use new ArrayList<>(Arrays.asList(...)) to create a modifiable ArrayList with multiple items in a single statement. For Java 9+, you can also use List.of("A", "B", "C") for an immutable list, or wrap it in new ArrayList<>(List.of(...)) for a modifiable one.