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Showing content from https://www.geeksforgeeks.org/java/arrays-aslist-method-in-java-with-examples/ below:

Arrays asList() Method in Java with Examples

Last Updated : 11 Jul, 2025

The Arrays.asList() method in Java is part of the java.util.Arrays class, which is used to convert an array into a fixed-size list. This method acts as a bridge between array-based and collection-based APIs, in combination with Collection.toArray().

Example:

Below is a simple example of the Arrays asList() method to convert an array of integers (using the Integer wrapper class) into a list.

Java


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

public class Example {
    public static void main(String[] args) {
        
        // Creating an array of Integer type
        Integer[] n = {1, 2, 3, 4, 5};

        // Getting the list view of the array
        List<Integer> l = Arrays.asList(n);

        System.out.println("" + l);
    }
}

Syntax of asList()

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

Parameters:

"T... a" is an array of elements to be converted into a List.
The "..." indicates that this is a varargs parameter and it allows multiple elements of type T to be passed as an array.

Important Points: The array type must be a wrapper class i.e. Integer, Float, for primitive data types i.e. int, float. You cannot pass int[], but you can pass Integer[]. Passing int[] will return a List<int[]> instead of a List<Integer>, as autoboxing does not occur in this case, which may cause errors in collection functions.

Return Value: List<T>: This method returns a fixed-size list that contains elements of the same type as the array elements.

Examples of Using the asList() Method in Java Using asList() Method with String Array

The below example demonstrates how to convert a String array into a fixed-size list using the asList() method.

Java


 // Java Program to Demonstrate asList() method
// of Arrays class for a string value
import java.util.*;

public class GFG {

    // Main driver method
    public static void main(String[] argv) throws Exception
    {

        // Try block to check for exceptions
        try {

            // Creating Arrays of String type
            String a[]
                = new String[] { "A", "B", "C", "D" };

            // Getting the list view of Array
            List<String> l = Arrays.asList(a);

            // Printing all the elements in list object
            System.out.println("" + l);
        }

        // Catch block to handle exceptions
        catch (NullPointerException e) {

            System.out.println("Exception thrown: " + e);
        }
    }
}

Using asList() Method with Integer Array

The below example demonstrates how to convert an Integer array into a fixed-size list using the asList() method.

Java


 // Java program to Demonstrate asList() method
// of Arrays class For an integer value
import java.util.*;

public class GFG {

    // Main driver method
    public static void main(String[] argv) throws Exception
    {
        // Try block to check for exceptions
        try {

            // Creating Arrays of Integer type
            Integer a[] = new Integer[] { 10, 20, 30, 40 };

            // Getting the list view of Array
            List<Integer> l = Arrays.asList(a);

            // Printing all the elements inside list object
            System.out.println("" + l);
        }

        // Catch block to handle exceptions
        catch (NullPointerException e) {

            System.out.println("Exception thrown: " + e);
        }
    }
}

UnsupportedOperationException with asList()

In this example, we will see that trying to change the list from asList() will cause an UnsupportedOperationException.

Java


 // Java Program to demonstrate asList() method
// Which returns fixed size list and
// throws UnsupportedOperationException
// if any element is added using add() method
import java.util.*;

public class GFG {

    public static void main(String[] argv) throws Exception
    {
        // Try block to check for exceptions
        try {

            // Creating Arrays of Integer type
            Integer a[] = new Integer[] { 10, 20, 30, 40 };

            // Getting the list view of Array
            List<Integer> l = Arrays.asList(a);

            // Adding another int to the list
            // As Arrays.asList() returns fixed size
            // list, we'll get
            // java.lang.UnsupportedOperationException
            l.add(50);

            // Printing all the elements of list
            System.out.println("" + l);
        }

        // Catch block to handle exceptions
        catch (UnsupportedOperationException e) {

            // Display message when exception occurs
            System.out.println("Exception thrown: " + e);
        }
    }
}

Output

Exception thrown: java.lang.UnsupportedOperationException

Output:

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