package myapp;

import java.io.IOException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.*;


public class ListServlet extends HttpServlet {
  InputOutPut io=new InputOutPut();

  @Override
  public void doGet(HttpServletRequest req, HttpServletResponse resp)
      throws IOException {
    resp.setContentType("text/plain");
    List<String> list=new ArrayList<>();
    list.add("String in list");
    try{
    io.write(list);
    resp.getWriter().println(io.read().get(0));
    }
    catch(Exception e){
      resp.getWriter().println(e.printStackTrace());
    }
  }
}

@@ -640,22 +640,17 @@
 n(e.
-printStackTrac
+getMessag
 e())

Update ListServlet.java