How to Convert an Array to a List in Java

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Hassan Saeed Feb 02, 2024
Java Java Array Java List
  1. Create an Empty List and Add All the Elements
  2. Use Arrays.asList() to Convert an Array to a List in Java
  3. Use new ArrayList<>(Arrays.asList(arr)) to Convert an Array to a List in Java
How to Convert an Array to a List in Java

This tutorial discusses three methods to convert an array to a list in Java.

Create an Empty List and Add All the Elements

It is a very trivial and obvious method. We can create an empty list, loop through all the elements in the array, and add them to the list.

The below example illustrates this:

import java.util.*;
import java.util.stream.*;

public class MyClass {
  public static void main(String args[]) {
    String[] myArray = new String[] {"1", "2", "3"};
    List<String> myList = new ArrayList<>();
    for (int i = 0; i < myArray.length; i++) {
      myList.add(myArray[i]);
    }
    System.out.println(myList);
  }
}

Output:

> [1, 2, 3]

Use Arrays.asList() to Convert an Array to a List in Java

We can use the built-in method provided by Arrays class to convert an array to a list - Arrays.asList(arr). Make sure to import java.util.* in your code.

The below example illustrates this.

import java.util.*;

public class MyClass {
  public static void main(String args[]) {
    String[] myArray = new String[] {"1", "2", "3"};
    List<String> myList = Arrays.asList(myArray);
    System.out.println(myList);
  }
}

Output:

> [1, 2, 3]

However, this method results in a fixed-size list, and we can not add more elements to it.

import java.util.*;

public class MyClass {
  public static void main(String args[]) {
    String[] myArray = new String[] {"1", "2", "3"};
    List<String> myList = Arrays.asList(myArray);
    myList.add("4");
  }
}

Output:

> Exception in thread "main" java.lang.UnsupportedOperationException
	at java.base/java.util.AbstractList.add(AbstractList.java:153)
	at java.base/java.util.AbstractList.add(AbstractList.java:111)
	at MyClass.main(MyClass.java:6)

Use new ArrayList<>(Arrays.asList(arr)) to Convert an Array to a List in Java

This method, new ArrayList<>(Arrays.asList(integers)); allows you to convert an array to a list, and add you can also add additional elements to the resulting list. Use the below example illustrates this:

import java.util.*;

public class MyClass {
  public static void main(String args[]) {
    String[] myArray = new String[] {"1", "2", "3"};
    List<String> myList = new ArrayList<>(Arrays.asList(myArray));
    System.out.println("After conversion from array to list: " + myList);
    myList.add("4");
    System.out.println("After adding a new element: " + myList);
  }
}

Output:

> After conversion from array to list: [1, 2, 3]
> After adding a new element: [1, 2, 3, 4]

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