.toArray from ArrayList to Array convertion, data type confusion

Question

I have confused myself with typecasting with this problem.

I have an ArrayList of chars that I want to convert into a String—an array of chars. So it goes something like this:

ArrayList<Character> message = new ArrayList<Character>();
String stringMessage = new String;
stringMessage = message.toArray(stringMessage);

Now the error that is given is:

"Syntax error, maybe a missing semicolon?"

which isn't very helpful.

Is there something wrong with how I cast this? Is it not possible to convert an ArrayList of characters into a String?

new String <-- error here. And message.toArray() will only accept an array as an argument, which stringMessage is not. — fge
– fge, Commented Mar 19, 2014 at 20:13
Even if toArray accepted String as argument (It doesn't), it still returns an array — user2591612
– user2591612, Commented Mar 19, 2014 at 20:14
possible duplicate of Converting ArrayList of Characters to a String? — user2591612
– user2591612, Commented Mar 19, 2014 at 20:15
First error can be resolved by simply writing String stringMessage;. But what are you really trying to do? The third line doesn't make sense. — Axel
– Axel, Commented Mar 19, 2014 at 20:25
To clearify: I'm using ArrayList as it has some advantages when handeling the data during the program, but for functions that can only handle the String object I need to do this conversion. Thank you all for the quick replies, fge's code solved my problem. — Tobias Tovedal
– Tobias Tovedal, Commented Mar 19, 2014 at 20:48

fge · Accepted Answer · 2014-03-19 20:17:47Z

0

You can do this:

final CharBuffer buf = CharBuffer.allocate(message.size());
for (final Character c: message)
    buf.put(c.charValue());
stringMessage = new String(buf.array());

You cannot use .toArray() directly since it would return a Character[], not a char[], and there is no String constructor accepting a Character[] as an argument...

answered Mar 19, 2014 at 20:17

fge

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