Converting String Array list to char array

Question

I am new to Java and trying to learn conversion from char ArrayList to char array. I am having some hard time to convert this.

 List<Character> code = new ArrayList<Character>();
 code.add("A");
 code.add("B");
 code.add("C");

This will display as [A, B, C]. What I want to do is to convert this array list to char[] array.

What I tried was the following:

char[] list = null;
for(int i=0; i<code.size(); i++){
    list[i] = code.get(i);
    System.out.println(list[i]); // this has the error
}

The error I am getting is java.lang.NullPointerException. I searched online but I couldn't find a "better" solution. Most of them are a conversion from string to char or vice versa. Perhaps I am missing some important knowledge about this. Again, I am new to Java and any help will be appreciated!.

The List interface includes a toArray method that does this conversion for you. Also, be careful about the difference between single and double quotes. — Dawood ibn Kareem
– Dawood ibn Kareem, Commented Apr 24, 2018 at 4:18
double quotes are wrong. It's supposed to be single. Thanks for this. — GoGo
– GoGo, Commented Apr 24, 2018 at 4:34

Domenick · Accepted Answer · 2018-04-24 04:21:02Z

1

You are getting a null pointer exception because you initialized the char array to null. Instead, you would want to initialize it to a new char array size equal to that of the ArrayList like:

char[] list = new char[code.size()];

Here is how all the code would look.

List<Character> code = new ArrayList<Character>();
code.add("A");
code.add("B");
code.add("C");


char[] list = new char[code.size()]; // Updated code

for(int i=0; i<code.size(); i++){
    list[i] = code.get(i);
    System.out.println(list[i]);
}

answered Apr 24, 2018 at 4:21

Domenick

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pramesh · Accepted Answer · 2018-04-24 04:23:57Z

0

Try this. Null Pointer exception is due to initializing to null

  List<Character> code = new ArrayList<Character>();
        code.add('A');
        code.add('B');
        code.add('C');


        Character[] arr = new Character[code.size()];
        arr = code.toArray(arr);

        System.out.println(arr);

answered Apr 24, 2018 at 4:23

pramesh

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Vishal Chhodwani · Accepted Answer · 2018-04-24 05:03:10Z

0

Initialize the char[] before using. something like

char[] list = new char[code.size()];

You are getting NullPointerException since the list variable is initialised with null.

edited Apr 24, 2018 at 5:03

Vishal Chhodwani

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answered Apr 24, 2018 at 4:18

piy26

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