Converting String to ArrayList<String> in Java

Question

I converted the ArrayList<String> list which contains "String1", "String2" to String by using list.toString(). The resulted string format is [String1, String2]. Is there any way to convert this result back to ArrayList<String>?

Have a look at the split method of the String class - it may be what you are looking for. — Dawood ibn Kareem
– Dawood ibn Kareem, Commented Oct 14, 2013 at 7:16
What is preventing you from keeping the ArrayList instead of converting it to a String and back int an ArrayList? Usually you can also convert a ArrayList<String> into a String[] with the toArray method. — Matthias
– Matthias, Commented Oct 14, 2013 at 7:22
Why do you need to do this? What are you trying to accomplish? — Ted Hopp
– Ted Hopp, Commented Oct 14, 2013 at 7:25
Nothing. I just wanted to know whether list.toString() is reversable or not. — Kiran
– Kiran, Commented Oct 14, 2013 at 7:35

newuser · Accepted Answer · 2013-10-14 07:23:56Z

4

Try applying the following code

String value = "[String1,String2,String3]";
value = value.subString(1,value.length()-1);
String[] split = value.split(",");
List<String> sampleList = Arrays.asList(split);

edited Oct 14, 2013 at 7:23

newuser

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answered Oct 14, 2013 at 7:21

Woody

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4 Comments

Dawood ibn Kareem Over a year ago

No. This won't necessarily give an ArrayList, which is what the question asked for. The right hand side of the last line needs to be new ArrayList<String>(Arrays.asList(split)).

Woody Over a year ago

@David Wallace, thanks for your suggestion. why the right hand side of the last line needs to be new ArrayList<String>(Arrays.asList(split))? Can you please clear my doubt?

Dawood ibn Kareem Over a year ago

Just because the OP said he wanted to have the result as an ArrayList, but the specification for Arrays.asList doesn't require that it returns an ArrayList. I believe that the current version of Java 7 does in fact return an ArrayList from Arrays.asList; but it's not required to by the specification, and a future version may return something different.

Woody Over a year ago

@David Wallace, thank you. Will follow your valuable feedback when I work on the same in future.

Sagar · Accepted Answer · 2013-10-14 07:18:18Z

1

create a new Class extending Array List

public class CustomArrayList<Item> extends ArrayList<Item> {

and override

toString

method, which could give a comma separated String representation. Now use

new CustomArrayList<Item>(Arrays.asList(list.toString().split(",")))

to get it back in ArrayList.

answered Oct 14, 2013 at 7:18

Sagar

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Comments

Suresh Atta · Accepted Answer · 2013-10-14 07:22:01Z

1

No direct way. Just get that String remove those [] from String and then split by , then add back to list.

Something like this,considering the given format.

    String s = "[String1, String2]";
    s = s.substring(1, s.length() - 1);
    List<String> list = new ArrayList<>();
    for (String string : s.split(",")) {
        list.add(string.trim());
    }

edited Oct 14, 2013 at 7:22

answered Oct 14, 2013 at 7:16

Suresh Atta

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1 Comment

chrylis -cautiouslyoptimistic- Over a year ago

Note that this isn't foolproof; if the internal strings have , (note the space, which should go in split), then you will end up with extra strings.

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