How to get the values of the objects inside an object??

Question

Hi,
I am trying to write code to display name and memory usage of all session attributes, in a recursive way.
I suppose reflection is needed here, but I can’t figure out how to get the values of the objects inside an object...
private void handleIt(String attributeName, Object attributeValue) {
     boolean isPrimitiveOrNull = ((null == attributeValue) ||
          (attributeValue.getClass().isPrimitive()));                                         
     if (isPrimitiveOrNull) {
          sb.append("{" + attributeName + ":" + sizeOf(attributeValue) + "}");
     } else {
          sb.append("{" + attributeName + ":" + sizeOf(attributeValue) + "{");               
          Field[] fields = attributeValue.getClass().getDeclaredFields();
          int lim = fields.length;
          String name;
          Object value = null;
          for (int i = 0; i < lim; i++) {
               name = fields.getName();
               //LOOK AT THIS LINE: !!!!!!!!!!!!!!!!!!!!!!!!!!!
               value = fields[i].get(obj); //I don´t know what 'obj' should be??
               handleIt(name, value);
          sb.append("}");               
Any suggestions will be greatly appreciated...

Answer 1

I realized that massive int objects called MAX_VALUE, MIN_VALUE and SIZE where causing the StackOverflow, so I removed them from the analysis.
This is the resultant code. But I think it isn’t accurate in calculating the real size of objects being got using reflexion.
Do you or somebody have any more suggestions?
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.lang.reflect.Field;
import java.util.Enumeration;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class SessionMeasurer extends HttpServlet {
     private static final long serialVersionUID = 1470488362727841992L;
     private StringBuilder sb = new StringBuilder();
     public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
          performTask(request, response);
     public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
          performTask(request, response);
     public void performTask(HttpServletRequest request, HttpServletResponse response) {
          HttpSession     session = request.getSession(false);     
          String attributeName = "";
          Object attributeValue = null;
          for (Enumeration<?> attributeNames = session.getAttributeNames(); attributeNames.hasMoreElements();) {
               attributeName = (String)attributeNames.nextElement();
               attributeValue = session.getAttribute(attributeName);
               handleIt(attributeName, attributeValue);               
          System.out.println(sb.toString());
     private void handleIt(String attributeName, Object attributeValue) {           
          if (attributeValue != null) {          
               boolean isPrimitive = attributeValue.getClass().isPrimitive();
               if (isPrimitive) {
                    sb.append("{" + attributeName + ":" + sizeOf(attributeValue) + "}");
               } else {
                    sb.append("{" + attributeName + ":" + sizeOf(attributeValue) + "{");               
                    Field[] fields = attributeValue.getClass().getDeclaredFields();
                    String name;
                    Object value = null;
                    int lim = fields.length;
                    for (int i = 0; i < lim; i++) {
                         name = fields.getName();                                                                                                         
                         if (!name.endsWith("_VALUE") && !name.equals("SIZE") && !name.equals("serialVersionUID")) {
                              try {
                                   value = fields[i].get(attributeValue);
                              } catch(Exception e) {
                                   //PENDIENTE: Tratamiento excepción
                              handleIt(name, value);
                    sb.append("}");               
     private int sizeOf(Object obj) {
          //Valid only for Serializables
          ByteArrayOutputStream baos = new ByteArrayOutputStream();
          ObjectOutputStream oos = null;     
          byte[] bytes = null;               
          try {          
               oos = new ObjectOutputStream(baos);
               oos.writeObject(obj);
               bytes = baos.toByteArray();
          } catch(Exception e) {               
               //PENDIENTE: Tratamiento excepción
          } finally {
               if (oos != null) {
                    try {
                         oos.close();
                    } catch(Exception e) {
                         //PENDIENTE: Tratamiento excepción                         
               if (baos != null) {
                    try {
                         baos.close();
                    } catch(Exception e) {
                         //PENDIENTE: Tratamiento excepción                         
          int size = -1;
          if (bytes != null) {
               size = bytes.length;
          return size;