CODEWITHSUNDEEP
javayaml
NRajkumar
NRajkumar

Reputation: 11

ClassCastException: LinkedHashMap cannot be cast to custom object using a Comparator in Java

Long time reader, first time query. I'm fairly new to java and I had a question specifically with using the comparator to compare dates from a yaml file that I saved as a linked hash map. After trying to use the comparator to sort the dates from my yaml file I received a ClassCastException: LinkedHashMap cannot be cast to Appointment

Here is the code: 

import org.yaml.snakeyaml.*;


public class DaysheetGenerator {
    public static void main(String[] args) throws Exception {
        //Creates a string with the file name
        String fileName = "resources/daysheet.yml";

        //Creates a new yaml daysheet 
        Yaml daysheet = new Yaml();

        // new instance of reader for YAML file
        Reader reader = null;

        try {
            // pass yaml file into the reader to create a new instance of     the YAML file for output
            reader = new FileReader(fileName);

            Map<String, List<Appointment>> lhm = new LinkedHashMap<>();

            // casted a as Map during load, saved to variable lhm
            lhm = (Map<String, List<Appointment>>)daysheet.load(reader);

            // get the value based on the key, "appointments"
            List<Appointment> list = lhm.get("appointments");

            // sort the list of appointments by date
            Collections.sort(list, new Comparator<Appointment>() {

                @Override
                public int compare(Appointment a1, Appointment a2) {                    
                    return a1.getDate().compareTo(a2.getDate());
                }

            });


            // print list
            System.out.println(list);

        }
        // if file cannot be found, print exception
        catch (FileNotFoundException e) {
            System.out.println("Could not find yaml file " + e);

            e.printStackTrace();
        }
        finally 
        {
            // close the reader after trying to read the file as long as the file exists
            if (null != reader) {
                try {
                    reader.close();
                } catch(final IOException ioe) {
                    System.err.println("Recieved exception when trying to close reader" + ioe);
                }
            }
        }

    }
}

Any help is appreciated. Thanks again!

PS: Im using Snakeyaml if that makes any difference

Upvotes: 0

Views: 857

Answers (1)

Deepak
Deepak

Reputation: 2905

lhm = (Map<String, List<Appointment>>)daysheet.load(reader);

This should be problematic statement . Here I think there is nothing wrong in comparator . daysheet.load(reader) is not giving you a linked hashmap and you are trying to cast it in LinkedHashMap

Upvotes: 1

Related Questions