public static ArrayList<Flat> retreiveFlat() throws ClassNotFoundException, IOException {

    FileInputStream fis = new FileInputStream("path/Flat.ser");
    ObjectInputStream ois = new ObjectInputStream(fis);
    Flat f;
    ArrayList<Flat> al = new ArrayList<Flat>();

    while (fis.available() > 0) {
        Object retrieved = ois.readObject();
        if(retrieved instanceof Flat) {
            f = (Flat) retrieved;
            if(f.getTypeOfFlat().equals("Double")) {
                al.add(f);
            }
        }
    }
    ois.close();
    return al;
}

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<%@ page import="Entity.Flat" %>
<%@ page import="java.util.*" %>
<%
    ArrayList<Flat> al = new ArrayList<Flat>();
    al = Flat.retreiveFlat();
    int i = 0;
    while(al.get(i) != null){
      //do something
    i++;}%>