Writing CSV file. myPackage.MyClass cannot be cast to java.lang.CharSequence

I need to write List<MyClass> myList into CSV file. In particular I need to write values . MyClass has the following implementation:

public class MyClass {

    private Object[] values;

//...

    @Override

    public String toString() 

      {

        String line = "";

        for (int i=0; i<this.getSize(); i++) {

            //if (this.values[i] != null) {

                line = line + this.values[i] + " ";

            //}

        }

        return line;

     }

}

The code is the following:

private void saveSolutionToCSV(List<MyClass> solution) {

    int columnSize = solution.get(0).getSize();

    try {

      FileWriter writer = new FileWriter("test.csv");

      Iterator result = solution.iterator();

      while(result.hasNext()) {

         for(int i = 0; i < columnSize; i++) {

            CharSequence element = (CharSequence)result.next(); 

            writer.append(element);

            if(i < columnSize - 1)

             writer.append(',');

         }

         writer.append('\n');

      }

    }

    catch(Exception e)

    {

      e.printStackTrace();

    }

}

And the error message is the following:

java.lang.ClassCastException: myPackage.MyClass cannot be cast to java.lang.CharSequence

How to solve this problem? Thx.