I want to convert String array to ArrayList. For example String array is like:
String[] words = new String[]{"ace","boom","crew","dog","eon"};
How to convert this String array to ArrayList?
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21+1; it's now the second link on google.Steve Kehlet– Steve Kehlet2013-03-22 00:32:56 +00:00Commented Mar 22, 2013 at 0:32
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3ArrayList<String> a = new ArrayList<>(Arrays.asList(words));Witold Kaczurba– Witold Kaczurba2017-03-16 15:07:17 +00:00Commented Mar 16, 2017 at 15:07
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You can do it in 3 basic ways. Using Collections.addAll, Arrays.asList and streams in Java 8 - Reference - codingeek.com/java/how-to-convert-array-to-list-in-javaHitesh Garg– Hitesh Garg2017-07-28 06:24:04 +00:00Commented Jul 28, 2017 at 6:24
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5 Answers
Use this code for that,
import java.util.Arrays;
import java.util.List;
import java.util.ArrayList;
public class StringArrayTest {
public static void main(String[] args) {
String[] words = {"ace", "boom", "crew", "dog", "eon"};
List<String> wordList = Arrays.asList(words);
for (String e : wordList) {
System.out.println(e);
}
}
}
11 Comments
Keale
In summary all you need is the line
List<String> wordList = Arrays.asList(words); . Is this correct?
Nicolai S
@Keale If
words is an array of strings, then, yes.Nicolai S
Beware: Arrays.asList(...) creates an AbstractList, not a real list. So you can do stuff like wordList.sort((a, b) -> a.length() - b.length()), but you can not do wordList.remove(0), or add to it. This will throw UnsupportedOperationException.
Witold Kaczurba
This code creates a List but it is not an ArrayList. So it is an incorrect answer. You cant delete elements from that List -> will throw an exception.
Jeff Holt
@Vito I have to agree that this is probably not a solution to a real problem unless someone can tell my why you would want to convert String[] to List and then not update the list.
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new ArrayList( Arrays.asList( new String[]{"abc", "def"} ) );
4 Comments
Manuel Spigolon
i think that this solution is better because
Arrays.asList return a java.util.Arrays.ArrayList.ArrayList<T>(T[]) so if you try to add something you'll get a java.lang.UnsupportedOperationExceptionDiptopol Dam
If you have limited number of elemenets in the array, it can be written as new ArrayList( Arrays.asList("abc", "def"));
Farbod Salamat-Zadeh
To avoid IDE warnings,
new ArrayList<>(...) worked for me as opposed to new ArrayList(...) (note the <>).
alvgarvilla
Best answer for me. With
List<String> wordList = Arrays.asList(words);, doing wordList instanceof ArrayList<String> will return false.Using Collections#addAll()
String[] words = {"ace","boom","crew","dog","eon"};
List<String> arrayList = new ArrayList<>();
Collections.addAll(arrayList, words);
4 Comments
Dinesh Arora
I like this solution. It is concise and clean.
Bathsheba
Quite why this is not the accepted answer is unknown to me.
Silambarasan
This is the right answer. asList is wrong. use Collection.addAll(arrayList, string array)...
Ashwin
This is the right solution if you want an mutable list from an array which is likely what we are looking for anyway. In the off chance an immutable list is needed, the above code accomplishes that task.
String[] words= new String[]{"ace","boom","crew","dog","eon"};
List<String> wordList = Arrays.asList(words);
2 Comments
Marko Topolnik
The result here is a
List, but not an ArrayList.
Scorpion
@MarkoTopolnik you are right, this needs to be wrapped so List<String> wordList = new ArrayList<String>(Arrays.asList(words));
in most cases the List<String> should be enough. No need to create an ArrayList
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
...
String[] words={"ace","boom","crew","dog","eon"};
List<String> l = Arrays.<String>asList(words);
// if List<String> isnt specific enough:
ArrayList<String> al = new ArrayList<String>(l);
