Timestamp problem with SQL Developer

SQL developer doesn't display timestamp for any query result.

Simple Fix:
In Oracle SQLDeveloper Go to: Tools >> Preferences >> Database > NLS Parameters and update your Date Format field to DD-MON-RR HH:MI:SS value

toArray() class cast exception

List<Record> recordsList = new ArrayList<Record>(2);

...

Record[] records = (Record[]) recordsList.toArray() ; //incorrect

Record[] records = (Record[]) recordsList.toArray(new Record[2]); //correct

Why Class cast exception ?

Recall that a Collection can contain objects of vastly different types. There's no 'general' rule that objects in a Collection must all be of the exact same type. So when toArray() is being calling, it allocates a typed array Object[] which has no sub-classes defined. Therefore casting it to any form such as (Record[]), will not work.

toArray() method can't see your cast so you have to tell it what kind of array to make.

create a folder structure outside of your application directory

private static final String UPLOAD_DIRECTORY = "uploads/img/"+now;

Date date = new Date() ;

SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy_MM_dd") ;

String now = dateFormat.format(date);

File uploadsFolder = new File(UPLOAD_DIRECTORY);

uploadsFolder.mkdirs();

File uploadedFile = new File(uploadsFolder, "fileName");

Replace Back slash with forward slash

String location = "uploads\img";

String backslash= System.getProperty(

location.replace(backslash,

or

location.replace("\\", "/");"/");"file.separator") ;

gwtupload - File Upload with GWT

1. Download last version of the library: gwtupload-x.x.x.jar and include it in your classpath.

2. Add these libraries to your application: commons-fileupload-1.2.jar, commons-io-1.3.1.jar and log4j.jar

3. Edit your module file: Xxx.gwt.xml.

<module>

  <!-- Include GWTUpload library -->
  <inherits name="gwtupload.GWTUpload"/>
  <!-- Load dinamically predefined styles in the library when the application starts -->
  <stylesheet src="Upload.css"/>
 
  <!-- Change this line with your project's entry-point -->
  <entry-point class="package.Xxx"/>
</module>

4. Edit your web.xml and include your customized servlet (extending ActionUpload and overriding executeAction). Be aware that the servlet provided depends on these libraries: commons-fileupload, commons-io and log4j, so include them in your package.
<context-param>
    <!-- max size of the upload request -->
    <param-name>maxSize</param-name>
    <param-value>3145728</param-value>
  </context-param>
  <context-param>
    <!-- Useful in development mode to slow down the uploads in fast networks.
         Put the number of milliseconds to sleep in each block received in the server.
         false or 0, means don't use slow uploads  -->
    <param-name>slowUploads</param-name>
    <param-value>200</param-value>
  </context-param>

  <servlet>
    <servlet-name>uploadServlet</servlet-name>
    <!-- This is the default servlet, it puts files in session -->
    <servlet-class>xxxxx.server.servlet.UploadServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>uploadServlet</servlet-name>
    <url-pattern>/xxx/upload</url-pattern>
  </servlet-mapping>

5. Create your client application
public class MultipleUploadSample implements EntryPoint {

  // A panel where the thumbnails of uploaded images will be shown
  private FlowPanel panelImages = new FlowPanel();

  public void onModuleLoad() {
    // Attach the image viewer to the document
    RootPanel.get("thumbnails").add(panelImages);
   
    // Create a new uploader panel and attach it to the document
    MultiUploader defaultUploader = new MultiUploader();
    RootPanel.get("default").add(defaultUploader);

    // Add a finish handler which will load the image once the upload finishes
    defaultUploader.addOnFinishUploadHandler(onFinishUploaderHandler);
  }

  // Load the image in the document and in the case of success attach it to the viewer
  private IUploader.OnFinishUploaderHandler onFinishUploaderHandler = new IUploader.OnFinishUploaderHandler() {
    public void onFinish(IUploader uploader) {
      if (uploader.getStatus() == Status.SUCCESS) {

        new PreloadedImage(uploader.fileUrl(), showImage);
       
        // The server sends useful information to the client by default
        UploadedInfo info = uploader.getServerInfo();
        System.out.println("File name " + info.name);
        System.out.println("File content-type " + info.ctype);
        System.out.println("File size " + info.size);

        // You can send any customized message and parse it
        System.out.println("Server message " + info.message);
      }
    }
  };

  // Attach an image to the pictures viewer
  private OnLoadPreloadedImageHandler showImage = new OnLoadPreloadedImageHandler() {
    public void onLoad(PreloadedImage image) {
      image.setWidth("75px");
      panelImages.add(image);
    }
  };
}

6. create your customized servlet
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Hashtable;
import java.util.List;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.io.FilenameUtils;
import org.apache.log4j.Logger;
import gwtupload.server.UploadAction;
import gwtupload.server.exceptions.UploadActionException;

public class UploadServlet extends UploadAction {

 private static final long serialVersionUID = 1L;
 private static Logger log = Logger.getLogger(UploadServlet.class);

 Hashtable<String, String> receivedContentTypes = new Hashtable<String, String>();

 /**
  * Maintain a list with received files and their content types.
  */
 Hashtable<String, File> receivedFiles = new Hashtable<String, File>();
 /**
  * Override executeAction to save the received files in a custom place
  * and delete this items from session. 
  * @return
  */

 @Override
 public String executeAction(HttpServletRequest request, List<FileItem> sessionFiles) throws UploadActionException {
  String response = "";
     int cont = 0;
     System.out.println("In ExecuteAction - UploadServlet Called");
     for (FileItem item : sessionFiles) {
      if (false == item.isFormField()) {
       cont ++;
          try {

           final String UPLOAD_DIRECTORY = "uploads/application/"+now;  
       
           Date date = new Date() ;
           SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy_MM_dd") ;
           String now = dateFormat.format(date);
         
           File uploadsFolder = new File(UPLOAD_DIRECTORY);
           uploadsFolder.mkdirs();
         
           String fileName = item.getName();
         
           // get only the file name not whole path
           if (fileName != null) {
            fileName = FilenameUtils. getName(fileName); // uploaded file filename
           }
         
           File uploadedFile = new File(uploadsFolder, fileName);
           item.write(uploadedFile);
         
           /// Save a list with the received files
           receivedFiles.put(item.getFieldName(), uploadedFile);
           receivedContentTypes.put(item.getFieldName(), item.getContentType());
         
           /// Send a customized message to the client.
           response += uploadedFile;
         
          } catch (Exception e) {
           throw new UploadActionException(e);
          }
      }
     }
    
     /// Remove files from session because we have a copy of them
     removeSessionFileItems(request);
    
     /// Send your customized message to the client.
     return response;
 }
  
 /**
  * Get the content of an uploaded file.
  */
 @Override
 public void getUploadedFile(HttpServletRequest request, HttpServletResponse response) throws IOException {
  String fieldName = request.getParameter(PARAM_SHOW);
     File f = receivedFiles.get(fieldName);
     if (f != null) {
      response.setContentType(receivedContentTypes.get(fieldName));
      FileInputStream is = new FileInputStream(f);
      copyFromInputStreamToOutputStream(is, response.getOutputStream());
     } else {
      renderXmlResponse(request, response, ERROR_ITEM_NOT_FOUND);
     }
   }
  
 /**
  * Remove a file when the user sends a delete request.
  */
 @Override
 public void removeItem(HttpServletRequest request, String fieldName)  throws UploadActionException {
  File file = receivedFiles.get(fieldName);
     receivedFiles.remove(fieldName);
     receivedContentTypes.remove(fieldName);
     if (file != null) {
      file.delete();
     }
 }
}

Class cast exception while casting the list object to the domain object

Problem:
TestDomainObj test = (TestDomainObj) session.createSQLQuery(query).list();  // class cast exception occurs

Solution:
(TestDomainObj) session.createSQLQuery(query)
.addEntity(TestDomainObj.class)
.list();

CreateQuery returns an java.lang.Object array. We can't cast it to our mapped object.
AddEntity fills the mapped object to the appropriate value, so that we can now use our mapped object other than object array

Unable to locate Spring NamespaceHandler

Error:
org.springframework.beans.factory.parsing.BeanDefinitionParsingException: Configuration problem: Unable to locate Spring NamespaceHandler for XML schema namespace [http://www.springframework.org/schema/tx] Offending resource: class path resource [applicationContext.xml]
Solution: Add spring-tx.jar to WEB-INF/lib

Error:
org.springframework.beans.factory.parsing.BeanDefinitionParsingException: Configuration problem: Unable to locate Spring NamespaceHandler for XML schema namespace [http://www.springframework.org/schema/security] Offending resource: class path resource [applicationContext.xml]
Solution: Add spring-core, spring-acl, spring-config, spring-web, spring-taglibs jars to WEB-INF/lib

To supress the class attribute 'sql-timestamp' in xstream

I declared createdate as java.util.date in DTO and in the hibernate mapping its been declared as timestamp. So it is trying to marshal a timestamp while datamember is date.
<createDate class="sql-timestamp"> .... </createDate>

To suppress this, either change the date to timestamp in your dto class or
you may set a java.sql.Timestamp as (another) default implementation for a java.util.Date or
you may remove the class attribute completely, something like

StringWriter writer = new StringWriter();
xstream.marshal(this, new PrettyPrintWriter(writer) {

@Override

public void addAttribute(final String key, final String value) {

if (!key.equals("class")) {

super.addAttribute(key, value);

}

}

});

problem inserting timestamp into the database

The equivalent hibernate type for Date is date, time, timestamp.

So check your hibernate level of mapping the date fields.
<property name="createDate" type ="timestamp">...</property>

Apache Tomcat V6x

Issue: OutOfMemoryError: Java heap space, PermGen space
To increase the memory in tomcat, edit catalina.bat file  (<tomcat-install>\bin\catalina.bat) and include
-Xms256m
-Xmx1024m
-XX:MaxPermSize=512m

Example:
set JAVA_OPTS=%JAVA_OPTS% 
-Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager
-Djava.util.logging.config.file="%CATALINA_BASE%\conf\logging.properties"
-Xms256m
-Xmx1024m
-XX:MaxPermSize=512m

GWT with Maven

1. Install the plugins depending on your eclipse version(my eclipse version is 3.5) - gwt for eclipse(http://dl.google.com/eclipse/plugin/3.5), m2eclipse(http://m2eclipse.sonatype.org/sites/m2e)
2. To create a maven based gwt project with GWT's webAppCreator utility, simply specifiy send -maven -noant as options. Say for example, webAppCreator -maven -noant -out C:\sample -junit C:\eclipse\plugins\org.junit4_4.5.0.v20090824\junit.jar com.testing.sample.sample
3. Once the folder structure is created, use mvn eclipse:eclipse and import the project to eclipse
4. Apply the tool kit settings to your project: Select your project - Right click - Google -Web Toolkit settings - check the use Google Web Toolkit and select the appropriate gwt version
5. Compile: Select your project - Right click - Google - GWT compile
6. Run: Select your project - Right click - Run as - Web Application

Maven Issues:
[ISSUE] M2_REPO (non modifiable)
Eclipse picks the value of M2_REPO from $MAVEN_HOME/conf/settings.xml using <localRepository> element. If nothing is specified, then ${user.home}/.m2 becomes the m2_repo path. Also verify the version of the maven from eclipse (preferences->maven->user settings).

Build Issues:
[ISSUE] The project doesn't have GWT SDK on its build path
check the order of your GWT SDK in the 'order and export' tab on your project build path.  gwt sdk library must appear before the maven dependencies. so, move it up in the order.

Compiler Issues:
[ERROR] Line 12: No source code is available for type com.google.gwt.junit.client.GWTTestCase; did you forget to inherit a required module?
add this to your *.gwt.xml <inherits name="com.google.gwt.junit.JUnit"/>

Run Issues:
[ERROR] Could not find host pages in the project 
Go to the project properties -> build path -> configure build path -> Select Google - WebApplication -> check 'This project has a WAR directory' - specify war directory as 'src/main/webapp'