Java

ArrayList

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Join Date: Apr 2006

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KimJack

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ArrayList

Oct 4th, 2009

Hi All,

Is it possible to convert an arraylist of chars to an array? For example:

ArrayList<Character> array = new ArrayList<Character>();

Can this be converted to an array of chars. I have tried using the toArray method but it is not working. Does anyone have any suggestions?

Thanks,
Kimjack

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JamesCherrill JamesCherrill is offline

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Re: ArrayList

Oct 4th, 2009

toArray does work. There's something wrong with how you are trying to use it. Post your code.

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mytime19

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Re: ArrayList

Oct 4th, 2009

posting a snippet might solve the problem in your case.

Regards,
Lucky

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KimJack

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Re: ArrayList

Oct 4th, 2009

Here is a snippet of code:

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Array<Character> letters = new ArrayList<Character>();
char[] characters =  new char[row * col];
...

public void createShuffleLetters()
	{
		//create letters
		for(char ch = 'a'; ch <='z'; ch++)
		{
			letters.add(ch);
		}
		//shuffle
		Collections.shuffle(letters);
		
		//convert arrayList to array
		letters.toArray(characters);		
	}

The line in red seems as if it should work, but I get the following error:
The method toArray(T[]) in the type ArrayList<Character> is not applicable for the arguments (char[])

I am trying to take an arraylist of characters and shuffle them then convert that arraylist to an array of chars. Any suggestions will be great.

Thanks,
Kimjack

Last edited by KimJack; Oct 4th, 2009 at 5:27 pm.

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llemes4011 llemes4011 is offline

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Re: ArrayList

Oct 4th, 2009

You're trying to cast a Character object to its primitive char type, which doesn't work.
Try using an array of Character instead of char. =)

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KimJack

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Re: ArrayList

Oct 4th, 2009

hmm, I have never heard of an array of Character. Would you provide an example?

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Re: ArrayList

Oct 4th, 2009

It's the same as a char array. You can make an array of any Object.

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Character[] ... = new Character[size];
Character[] ... = new Character[size];

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Re: ArrayList

Oct 5th, 2009

To elaborate on what llemes said (and he is correct), you are trying to use the following method "public Object[] toArray(Object[] a)" which takes an array of Objects, but you are passing in an array of chars. "char" is a primitive type, not an Object, which is why you are getting the error. On the other hand, the Character class (like every other class), "is-an" Object, so you can use that. Or you could simply use:

Character[] theChars = letters.toArray();

Out.