Java convert a string to list of enums [duplicate]

Question

I have a string as follows:

"[Monday, Tuesday]"

I want to convert this string to a list of enums of type "Day". My "Day" enum is as follows:

public enum Day {
    Monday,Tuesday;
}

I obtained my input string by calling toString() on a List of "Day"s. As follows:

List<Day> days = new ArrayList<Day>();
days.add(Day.Monday);
days.add(Day.Tuesday);

String input = days.toString();

I know that I can parse the input string by commas and brackets. But, is there any efficient way to do this?

To repeat, I want to covert string to a list of enums.

** EDIT **

Question is not just about converting String to enum and vice versa. It involves lists and string parsing.

Answer 1

In case you use Java 8:

//assume your Day enum has more values
String string = "[Monday, Wednesday, Tuesday, Friday, Thursday]";
String stringWithNoBrackets = string.substring(1, string.length() - 1);
List<Days> days = Arrays.asList(stringWithNoBrackets.split(",\\s+"))
        .stream()
        .map(Days::valueOf)
        .collect(Collectors.toList());
System.out.println(days);

Also, we don't need to convert the array into a list, using less code:

List<Days> days2 = Arrays.stream(stringWithNoBrackets.split(",\\s+"))
    .map(Days::valueOf)
    .collect(Collectors.toList());

Answer 2

Your question doesn't really make much sense. If you want to send or store list of enums then you can simply serialize and deserialize it since ArrayList and each enum are Serializable.

Example:

List<Day> ofiginalList = new ArrayList<Day>();
ofiginalList.add(Day.Monday);
ofiginalList.add(Day.Tuesday);

ByteArrayOutputStream bout = new ByteArrayOutputStream();

ObjectOutput out = new ObjectOutputStream(bout);
out.writeObject(ofiginalList);

ByteArrayInputStream bin = new ByteArrayInputStream(bout.toByteArray());
ObjectInput in = new ObjectInputStream(bin);

List<Day> deserializedList = (List<Day>) in.readObject();
System.out.println(deserializedList);

Output: [Monday, Tuesday].

Answer 3

You can try doing something like

List<Day> days = new ArrayList<>();
StringTokenizer tokenizer = new StringTokenizer("[Monday, Tuesday]", "[], ");
while (st.hasMoreTokens()) {
  String token = st.nextToken();
  days.add(Day.valueOf(Day.class, token));
}