Convert ArrayList into a String

Question

Is there a simple way of converting an ArrayList that contains only characters into a string? So say we have

ArrayList<Character> arrayListChar = new ArrayList<Character>();
arrayListChar.add(a);
arrayListChar.add(b);
arrayListChar.add(c);

So the array list contains a, b, and c. Ideally what I'd want to do is turn that into a String "abc".

Possible duplicate of question: http://stackoverflow.com/q/6324826/601409 — EkcenierK, Dec 08 '11 at 14:20
even better answers were provided here: http://stackoverflow.com/questions/523871/best-way-to-concatenate-list-of-string-objects It's about concatenating list of Strings, but close. — jFrenetic, Dec 08 '11 at 14:24

score 3 · Answer 1 · answered Dec 08 '11 at 14:19

3

Iterator<Character> it = arrayListChar.iterator();
StringBuilder sb = new StringBuilder();

while(it.hasNext()) {
    sb.append(it.next());
}

System.out.println(sb.toString());

answered Dec 08 '11 at 14:19

Jan Vorcak

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score 3 · Answer 2 · answered Dec 08 '11 at 14:21

3

You could use Apache Common Lang's StringUtils class. It has a join() function like you find in PHP.

Then the code:

StringUtils.join(arrayListChar, "")

would generate:

abc

answered Dec 08 '11 at 14:21

Jonathan M

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score 1 · Answer 3 · answered Dec 08 '11 at 14:42

    int size = list.size();
    char[] chars = new char[size];
    for (int i = 0; i < size; i++) {
        if (list.size() != size) {
            throw new ConcurrentModificationException();
        }
        chars[i] = list.get(i);
    }
    String s = new String(chars);

score 1 · Answer 4 · answered Dec 08 '11 at 14:52

1

Using regex magic:

String result = list.toString().replaceAll(", |\\[|\\]", "");

Get the String representation of the list, which is

[a, b, c]

and then remove the strings "[", "]", and ", ".

answered Dec 08 '11 at 14:52

Tudor

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score 0 · Answer 5 · answered Dec 08 '11 at 14:18

0

You can override it's toString method and implement the String formatting therein.

answered Dec 08 '11 at 14:18

mre

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score 0 · Answer 6 · answered Dec 08 '11 at 14:22

0

Override toString method of ArrayList or the better to extend the ArrayList class so that you may use old ArrayList toString() somewhere else in the code

answered Dec 08 '11 at 14:22

Wozza · Answer 7 · 2011-12-08T15:01:31.993

0

    String s = "";
    for(Character i : arrayListChar)
           s += i;

EDIT - as pointed out already, you should only use code like this if the number of strings to concatenate is small.

edited Dec 08 '11 at 15:01

answered Dec 08 '11 at 14:22

Wozza

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String are immutable, you will create a new string for every concatenation. Very bad use of memory. Try using a StringBuilder instead. – Tudor Dec 08 '11 at 14:26

Convert ArrayList into a String

7 Answers7