[java] Converting String array to java.util.List

How do I convert a String array to a java.util.List?

The Simplest approach:

String[] stringArray = {"Hey", "Hi", "Hello"};

List<String> list = Arrays.asList(stringArray);

As of Java 8 and Stream API you can use Arrays.stream and Collectors.toList:

String[] array = new String[]{"a", "b", "c"};
List<String> list = Arrays.stream(array).collect(Collectors.toList());

This is practical especially if you intend to perform further operations on the list.

String[] array = new String[]{"a", "bb", "ccc"};
List<String> list = Arrays.stream(array)
                          .filter(str -> str.length() > 1)
                          .map(str -> str + "!")
                          .collect(Collectors.toList());

First Step you need to create a list instance through Arrays.asList();

String[] args = new String[]{"one","two","three"};
List<String> list = Arrays.asList(args);//it converts to immutable list

Then you need to pass 'list' instance to new ArrayList();

List<String> newList=new ArrayList<>(list);

List<String> strings = Arrays.asList(new String[]{"one", "two", "three"});

This is a list view of the array, the list is partly unmodifiable, you can't add or delete elements. But the time complexity is O(1).

If you want a modifiable a List:

List<String> strings = 
     new ArrayList<String>(Arrays.asList(new String[]{"one", "two", "three"}));

This will copy all elements from the source array into a new list (complexity: O(n))

Use the static List list = Arrays.asList(stringArray) or you could just iterate over the array and add the strings to the list.

On Java 14 you can do this

List<String> strings = Arrays.asList("one", "two", "three");

import java.util.Collections;

List myList = new ArrayList();
String[] myArray = new String[] {"Java", "Util", "List"};

Collections.addAll(myList, myArray);