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javaarrayscollections
Hitesh Dangi
Hitesh Dangi

Reputation: 1536

Converting String array to java.util.List

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

Upvotes: 146

Views: 276026

Answers (9)

orly.sharon
orly.sharon

Reputation: 193

If you have a list like this: "one, two, three."

You can use this code :

  Arrays.asList(StringUtil.split("one, two, three",','))

or

    public static List<String> convertStringToList(String listAsString) {
    String[] list = listAsString.split("\\s*,\\s*");
    return Arrays.stream(list).collect(Collectors.toList());
}

Upvotes: 1

Bouke Woudstra
Bouke Woudstra

Reputation: 301

If the result should be a readonly list then you can use List.of(nameOfArray)

@Test
public void shouldMapArrayToList(){
    // given
    var testArray = new String[]{"1", "2", "3" };

    // when
    List<String> result = List.of(testArray);

    // then
    assertEquals("1", result.get(0));
    assertEquals("2", result.get(1));
    assertEquals("3", result.get(2));
}

Upvotes: 1

Nikolas
Nikolas

Reputation: 44368

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());

Upvotes: 6

Dilantha
Dilantha

Reputation: 188

On Java 14 you can do this

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

Upvotes: 1

CoderSam
CoderSam

Reputation: 551

The Simplest approach: 

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

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

Upvotes: 15

Syam Elakapalli
Syam Elakapalli

Reputation: 256

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);

Upvotes: 8

Slick
Slick

Reputation: 850

import java.util.Collections;

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

Collections.addAll(myList, myArray);

Upvotes: 22

Andreas Dolk
Andreas Dolk

Reputation: 114757

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))

Upvotes: 289

dst
dst

Reputation: 1788

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

Upvotes: 36

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