Convert an Array to a List in Java

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  4. Convert an Array to a List in Java
Hassan Saeed Jan 30, 2023 Sep 22, 2020
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
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.stream.*;  
import java.util.*;

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]

Related Article - Java Array

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