loading ArrayList<String> from java properties file

Question

I'm reading from a properties-file using this method:

public void loadConfigFromFile(String path) {

        Properties prop = new Properties();

        InputStream input = null;



        try {



            //input = new FileInputStream("config.properties");

            input = new FileInputStream(path);



            // load a properties file

            prop.load(input);



            // .... saved like this:

            // emails: abc@test.com, bbc@aab.com, .....

            String wordsS = prop.getProperty("keywords");

            String emailS = prop.getProperty("emails");

            String feedS = prop.getProperty("feeds");



            emails = Arrays.asList(emailS.split(",")); //ERROR !!

            words = Arrays.asList( wordsS.split(","))); //ERROR !!

            feeds = Arrays.asList( feedS.split(",")); //ERROR !!

            allXHours = Float.valueOf(prop.getProperty("frequency"));



        } catch (IOException ex) {

            ex.printStackTrace();

        } finally {

            if (input != null) {

                try {

                    input.close();

                } catch (IOException e) {

                    e.printStackTrace();

                }

            }

        }

    }

the fields to be written are declared as follows:

 private ArrayList<String> emails = new ArrayList<>(

            Arrays.asList("f00@b4r.com", "test@test.com")

    );



    private LinkedList<String> words = new LinkedList<>(

            Arrays.asList("vuln", "banana", "pizza", "bonanza")

    );



    private LinkedList<String> feeds = new LinkedList<>(

            Arrays.asList("http://www.kb.cert.org/vulfeed",

                    "https://ics-cert.us-cert.gov/advisories/advisories.xml",

                    "https://ics-cert.us-cert.gov/alerts/alerts.xml")

    );

..so the compiler shows me the following Information, which I don't know how to use:

Incompatible types. Required
ArrayList<String>
but 'asList' was inferred to
List<T>
: no instance(s) of type variable(s) T exist so that
List<T>
conforms to
ArrayList<String>

How to circumvent this?

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Answer 1

The problem is the type of the declared variable that you assign to emails = Arrays.asList(emailS.split(","));.
According to the compilation error, it is declared as ArrayList but Arrays.asList() returns a List.
You cannot assign a List to an ArrayList while you can do the reverse.

Besides Arrays.asList() return an instance of a private class : java.util.Arrays.ArrayList that is not the same that the ArrayList variable that you declare : java.util.ArrayList. So even a downcast to ArrayList would not work and cause a ClassCastException.

Change the declared variable from ArrayList<String> emails to List<String> emails and do the same thing for two other ArrayList variables.

loading ArrayList<String> from java properties file

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