Adding comma separated strings to an ArrayList and vice versa

Question

How to add a comma separated string to an ArrayList? My string \"returnedItems\" could hold 1 or 20 items which I\'d like to add to my ArrayList \"selItemArrayList\".

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Answer 1

split and asList do the trick:

String [] strings = returnedItems.split(",");
List<String> list = Arrays.asList(strings);

Answer 2

If the strings themselves can have commas in them, things get more complicated. Rather than rolling your own, consider using one of the many open-source CSV parsers. While they are designed to read in files, at least OpenCSV will also parse an individual string you hand it.

• Commons CSV
• OpenCSV
• Super CSV
• OsterMiller CSV

Answer 3

String list = "one, two, three, four";
String[] items = list.split("\\p{Punct}");
List<String> aList = Arrays.asList(items);
System.out.println("aList = " + aList);
StringBuilder formatted = new StringBuilder();

for (int i = 0; i < items.length; i++)
{
    formatted.append(items[i].trim());
    if (i < items.length - 1) formatted.append(',');
}

System.out.println("formatted = " + formatted.toString());

Answer 4

Simple one-liner:

selItemArrayList.addAll(Arrays.asList(returnedItems.split("\\s*,\\s*")));

Of course it will be more complex if you have entries with commas in them.

Answer 5

String csv = "Apple, Google, Samsung";

step one : converting comma separate String to array of String

String[] elements = csv.split(",");

step two : convert String array to list of String

 List<String> fixedLenghtList = Arrays.asList(elements);

step three : copy fixed list to an ArrayList ArrayList listOfString = new ArrayList(fixedLenghtList);

System.out.println("list from comma separated String : " + listOfString);

System.out.println("size of ArrayList : " + listOfString.size()); Output :

list of comma separated String : [Apple, Google, Samsung]


size of ArrayList : 3

Answer 6

This can help:

for (String s : returnedItems.split(",")) {
    selItemArrayList.add(s.trim());
}

//Shorter and sweeter
String [] strings = returnedItems.split(",");
selItemArrayList = Arrays.asList(strings);

//The reverse....

StringBuilder sb = new StringBuilder();
Iterator<String> iter = selItemArrayList.iterator();
while (iter.hasNext()) {
    if (sb.length() > 0) 
        sb.append(",");
    sb.append(iter.next());
}

returnedItems = sb.toString();