Is there a way to convert a string to an array in java?

Question

I want to convert this String:

String s = "[\"val1\", \"val2\", \"val3\"]";

to an array or an ArrayList (without regex and split). It's from a Database, and it's generic. It's also possible to have commas inside the high quotes.

Is this possible?

Answer 1

Unfortunately, there is no java API that would directly parse this list.

This snippet would work for this String:

    String s = "[\"val1\", \"val2\", \"val3\"]";
    String[] arr = s.replace("[", "").replace("]", "").split("\\s*,\\s*");
    List<String> list = Arrays.asList(arr);

If the string contains [ or ] somewhere else, then the snippet above won't work.

I suggest to figure out what is this. Is this a JSON array? Then use a JSON parser. Is this a csv with additional [ and ] ? Then use a CSV parser.

Answer 2

String json = "[\"val1\", \"val2\", \"val3\"]";
JSONArray jsonarray = new JSONArray(json);
List<Object> objects = jsonarray.toList();

Thanks to @TamasRev

Answer 3

Yes, there is a way using Regex.

import java.util.ArrayList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

class T1 {
    public static void main(String[] args) {
        final String REGEX = "\\b([\\w]+)\\b";
        String INPUT = "[\"val1\", \"val2\", \"val3\"]";

        Pattern p = Pattern.compile(REGEX);
        Matcher m = p.matcher(INPUT);   // get a matcher object
        List<String> myList = new ArrayList<>();

        while(m.find()) {
            myList.add(m.group());
        }

        System.out.println(myList);
    }
}

Answer 4

You can use a String tokenizer and set as delimiters " \\",[]" . This is my example. I've used an array, but it's very simple to convert it in a ArrayList if you want.

public static void main(String[] args) {
    String s = "[\"val1\", \"val2\", \"val3\"]";

    String delims = " \",[]";

    StringTokenizer st = new StringTokenizer(s, delims);

    System.out.println("Num of Token = " + st.countTokens());
    String[] myArr= new String[st.countTokens()];


    for(int i=0; i<myArr.length && st.hasMoreTokens(); i++)
        myArr[i]=st.nextToken();

    //output
    System.out.println(Arrays.toString(myArr));
}

Your output will be:

Num of Token = 3

[val1, val2, val3]