How to split a returned List<String> by comma from a text file?

Question

I'm reading from a text file (usernames.txt) which has values separated by commas:

AA328747, AA337748, AA057393, AA290457, AA467620, AA225950, AA352105, AA108183, AA057070,

using my method:

public static List<String> readUsername(String path){

        File file = new File(path);     
        Reader fileReader;
        List<String> list = new ArrayList<String>();
        String username;

        try 
        {
            fileReader = new FileReader(file);
            BufferedReader br = new BufferedReader(fileReader);
            username = br.readLine();

            while (username != null)
            {
                list.add(username);
                username= br.readLine();
            }

            br.close();
        } 
        catch (FileNotFoundException e)
        {
            e.printStackTrace();
        } 
        catch (IOException e) 
        {
            e.printStackTrace();
        }           

        return list;        
    }

And I try to print it out to console:

List<String> usernameList = readUsername(fileStr);

    for (int i=0; i < usernameList.size(); i++)
    {
        System.out.println(usernameList.size());
        System.out.println(usernameList.get(i) + " end");
    }

where fireStr is just my path file string.

And it prints well but the size of the list object (usernameList.size()) is only 1.

The print out is:

AA328747, AA337748, AA057393, AA290457, AA467620, AA225950, AA352105, AA108183, AA057070, end

How I want it to print out is like:

AA328747 end

AA337748 end

AA057393 end

AA290457 end

AA467620 end

AA225950 end

AA352105 end

AA108183 end

AA057070 end

And the list size should be more than 1 items (In my example it should be 9 for nine usernames in the text file).

How do I get rid of the commas and just evaluate each username as separate strings instead of one big string?

Answer 1

I believe you want the split() method. You can use Collections#addAll to directly add all the elements from the Array produced by split to the List:

while (username != null)
{
     Collections.addAll(list, username.split(","));
     username= br.readLine();
}