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oquidave

servlet constructor instatiation

Jul 17th, 2013
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Java 2.25 KB | None | 0 0
  1. package com.versefeed.crud;
  2.  
  3. import java.io.IOException;
  4. import java.util.List;
  5.  
  6. import javax.servlet.http.HttpServlet;
  7. import javax.servlet.http.HttpServletRequest;
  8. import javax.servlet.http.HttpServletResponse;
  9. import javax.swing.text.Utilities;
  10.  
  11. import com.google.appengine.api.datastore.DatastoreService;
  12. import com.google.appengine.api.datastore.DatastoreServiceFactory;
  13. import com.google.appengine.api.datastore.Entity;
  14. import com.google.appengine.api.datastore.Text;
  15.  
  16. public class CrudServlet extends HttpServlet {
  17.  
  18.     private DatastoreService ds;
  19.     private String entityKind;
  20.     private CrudDsUtilities utilities;
  21.    
  22.     private void CrudServlet() {
  23.         ds = DatastoreServiceFactory.getDatastoreService();
  24.         utilities = new CrudDsUtilities();
  25.  
  26.     }
  27.  
  28.     public void doGet(HttpServletRequest req, HttpServletResponse resp)
  29.             throws IOException {
  30.  
  31.         String operation = req.getParameter("op");
  32.         String verseTitle, verseRef, verseBody;
  33.         long verseId;
  34.         switch (operation) {
  35.  
  36.         case "view":
  37.             verseId = Long.getLong(req.getParameter("verseId"));
  38.             entityKind = req.getParameter("entityKind");
  39.  
  40.             break;
  41.  
  42.         case "viewverses":
  43.             entityKind = req.getParameter("entitykind");
  44.             System.out.println("entityKind: "+ entityKind);
  45.             this.viewVerses(req, resp);
  46.             break;
  47.  
  48.         default:
  49.             break;
  50.         }
  51.  
  52.     }
  53.  
  54.     public void viewVerse(long verseId) {
  55.  
  56.     }
  57.  
  58.     public void viewVerses(HttpServletRequest req, HttpServletResponse resp) {
  59.        
  60. //throwing java.lang.NullPointerException on this line! it doesn't see "utilities" as already instantiated in the constructor.
  61.         List<Entity> verses = utilities.getEntitiesAsList(entityKind);
  62.        
  63.         try {
  64.             // Set the attribute and Forward to hello.jsp
  65.             req.setAttribute ("verses", verses); // to save your temporary calculations.
  66.             req.getRequestDispatcher("/verses.jsp").forward(req, resp);
  67.         } catch (Exception ex) {
  68.             ex.printStackTrace ();
  69.         }
  70.  
  71.     }
  72.  
  73. }// close class
  74.  
  75. //traceback
  76.  
  77. java.lang.NullPointerException
  78.     at com.versefeed.crud.CrudServlet.viewVerses(CrudServlet.java:109)
  79.     at com.versefeed.crud.CrudServlet.doGet(CrudServlet.java:68)
  80.     at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
  81.     at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
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