Definition to a wrapper class

Hi,
I'm creating a class to my SCJD cert impl that has a protected RandomAccessFile reference member. I've designed this member as protected since subclasses really need to access it.
My dilema is that I thought of this class as a wrapper to that member, but, the way it is, classes from the same package can access it too, and I didn't really need/want that. I think of a wrapper as something that really encapsulates something, so...
Am I breaking any rules with the definition of wrapper classes? Does anyone know if any Java class has the same dilema?
thanks in advance,
Tales

subclasses
really need to access it.Unlikely. I don't think I've ever created a protected member variable in 8 or 9 years of writing Java code.
My dilema is that I thought of this class as a
wrapper to that member,I would think the thing being wrapped would be private.
but, the way it is, classes
from the same package can access it too,Yes. Protected access allows classes in the same package to access it.
and I didn't
really need/want that.Then I think you're misunderstanding packages and/o subclassing. A package is a "closer" relationship than a parent/child relationship. It's perfectly natural for classes in the same package to be able to access a protected member. If it's a problem that they're able to access that member, then they probably shouldn't be in that package.
Am I breaking any rules with the definition of
wrapper classes? I'm not sure what the formal definition is--or if there is one--but I think making the wrapped thing non-private does violate the spirit of wrapper classes.
Also, I don't know if it's a good idea for a wrapper class not to be final.

Similar Messages

Failed to Generate Wrapper Class Error With Postgresql

Hello,
Sorry if this comes across twice, I posted it first through the Google Groups interface, but I haven't seen it show up on the dev2dev forum interface. So here it is again.
I've read the following threads that seem to be related to this
question:
http://groups-beta.google.com/group/weblogic.developer.interest.jdbc/browse_thread/thread/dc8f0a9ee03e9b9f/f0a70a673db3bb52
http://groups-beta.google.com/group/weblogic.developer.interest.jdbc/browse_thread/thread/4f3b71c77dca30c4/4ed2e1c7b76a0c7b
I also followed the links in the second post ( I also found them via
Google as well ). I've been very sure the Postgresql JDBC driver is
definitely in the class path. I'm able to load it with Class.forName()
from a JSP page and then use DriverManager to get a connection that
works. So that definitely means the driver is found.
What else can cause this?
The only really odd thing I am doing is running Weblogic on OS X,
10.3.7 with all the updates. I know that this Weblogic setup works
since I work on Oracle all day (using the provided Weblogic driver in
8.1SP3). Just when I try to create a Postgresql connection for testing
our app against Postgresql.
I've tried it on Windows with Weblogic 8.1SP3 and it works, so I know
Weblogic is capable of using this driver.
My exact stacktrace is:
java.lang.RuntimeException: Failed to Generate Wrapper Class
at
weblogic.utils.wrapper.WrapperFactory.createWrapper(WrapperFactory.java:183)
at
weblogic.jdbc.wrapper.JDBCWrapperFactory.getWrapper(JDBCWrapperFactory.java:171)
at weblogic.jdbc.pool.Driver.allocateConnection(Driver.java:248)
at weblogic.jdbc.pool.Driver.connect(Driver.java:164)
at weblogic.jdbc.jts.Driver.getNonTxConnection(Driver.java:507)
at weblogic.jdbc.jts.Driver.connect(Driver.java:139)
at
weblogic.jdbc.common.internal.RmiDataSource.getConnection(RmiDataSource.java:305)
at jsp_servlet.__direct._jspService(direct.jsp:13)
at weblogic.servlet.jsp.JspBase.service(JspBase.java:33)
at
weblogic.servlet.internal.ServletStubImpl$ServletInvocationAction.run(ServletStubImpl.java:996)
at
weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:419)
at
weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:463)
at
weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:315)
at
weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:6452)
at
weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321)
at
weblogic.security.service.SecurityManager.runAs(SecurityManager.java:118)
at
weblogic.servlet.internal.WebAppServletContext.invokeServlet(WebAppServletContext.java:3661)
at
weblogic.servlet.internal.ServletRequestImpl.execute(ServletRequestImpl.java:2630)
at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:219)
at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:178)
at weblogic.jdbc.jts.Driver.wrapAndThrowSQLException(Driver.java:458)
at weblogic.jdbc.jts.Driver.getNonTxConnection(Driver.java:511)
at weblogic.jdbc.jts.Driver.connect(Driver.java:139)
at
weblogic.jdbc.common.internal.RmiDataSource.getConnection(RmiDataSource.java:305)
at jsp_servlet.__direct._jspService(direct.jsp:13)
at weblogic.servlet.jsp.JspBase.service(JspBase.java:33)
at
weblogic.servlet.internal.ServletStubImpl$ServletInvocationAction.run(ServletStubImpl.java:996)
at
weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:419)
at
weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:463)
at
weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:315)
at
weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:6452)
at
weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321)
at
weblogic.security.service.SecurityManager.runAs(SecurityManager.java:118)
at
weblogic.servlet.internal.WebAppServletContext.invokeServlet(WebAppServletContext.java:3661)
at
weblogic.servlet.internal.ServletRequestImpl.execute(ServletRequestImpl.java:2630)
at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:219)
at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:178)
What is going on at the place where this crashes? Is there a way find
out what class it really can't find?
Thanks,
Patrick

Patrick,
1. Could you try to test the postgress connection pool using
"Test Connection" on the pool set up page?
2. Could you compare config.xml for broken and working installations
in part of the connection pool settings?
Regards,
Slava Imeshev
"Patrick Burleson" <[email protected]> wrote in message
Sorry if this comes across twice, I posted it first through the Google Groups interface, but I haven't seen it show up on thedev2dev forum interface. So here it is again.
>
I've read the following threads that seem to be related to this
question:
http://groups-beta.google.com/group/weblogic.developer.interest.jdbc/browse_thread/thread/dc8f0a9ee03e9b9f/f0a70a673db3bb52
http://groups-beta.google.com/group/weblogic.developer.interest.jdbc/browse_thread/thread/4f3b71c77dca30c4/4ed2e1c7b76a0c7b
I also followed the links in the second post ( I also found them via
Google as well ). I've been very sure the Postgresql JDBC driver is
definitely in the class path. I'm able to load it with Class.forName()
from a JSP page and then use DriverManager to get a connection that
works. So that definitely means the driver is found.
What else can cause this?
The only really odd thing I am doing is running Weblogic on OS X,
10.3.7 with all the updates. I know that this Weblogic setup works
since I work on Oracle all day (using the provided Weblogic driver in
8.1SP3). Just when I try to create a Postgresql connection for testing
our app against Postgresql.
I've tried it on Windows with Weblogic 8.1SP3 and it works, so I know
Weblogic is capable of using this driver.
My exact stacktrace is:
java.lang.RuntimeException: Failed to Generate Wrapper Class
at
weblogic.utils.wrapper.WrapperFactory.createWrapper(WrapperFactory.java:183)
at
weblogic.jdbc.wrapper.JDBCWrapperFactory.getWrapper(JDBCWrapperFactory.java:171)
at weblogic.jdbc.pool.Driver.allocateConnection(Driver.java:248)
at weblogic.jdbc.pool.Driver.connect(Driver.java:164)
at weblogic.jdbc.jts.Driver.getNonTxConnection(Driver.java:507)
at weblogic.jdbc.jts.Driver.connect(Driver.java:139)
at
weblogic.jdbc.common.internal.RmiDataSource.getConnection(RmiDataSource.java:305)
at jsp_servlet.__direct._jspService(direct.jsp:13)
at weblogic.servlet.jsp.JspBase.service(JspBase.java:33)
at
weblogic.servlet.internal.ServletStubImpl$ServletInvocationAction.run(ServletStubImpl.java:996)
at
weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:419)
at
weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:463)
at
weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:315)
at
weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:6452)
at
weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321)
at
weblogic.security.service.SecurityManager.runAs(SecurityManager.java:118)
at
weblogic.servlet.internal.WebAppServletContext.invokeServlet(WebAppServletContext.java:3661)
at
weblogic.servlet.internal.ServletRequestImpl.execute(ServletRequestImpl.java:2630)
at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:219)
at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:178)
at weblogic.jdbc.jts.Driver.wrapAndThrowSQLException(Driver.java:458)
at weblogic.jdbc.jts.Driver.getNonTxConnection(Driver.java:511)
at weblogic.jdbc.jts.Driver.connect(Driver.java:139)
at
weblogic.jdbc.common.internal.RmiDataSource.getConnection(RmiDataSource.java:305)
at jsp_servlet.__direct._jspService(direct.jsp:13)
at weblogic.servlet.jsp.JspBase.service(JspBase.java:33)
at
weblogic.servlet.internal.ServletStubImpl$ServletInvocationAction.run(ServletStubImpl.java:996)
at
weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:419)
at
weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:463)
at
weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:315)
at
weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:6452)
at
weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321)
at
weblogic.security.service.SecurityManager.runAs(SecurityManager.java:118)
at
weblogic.servlet.internal.WebAppServletContext.invokeServlet(WebAppServletContext.java:3661)
at
weblogic.servlet.internal.ServletRequestImpl.execute(ServletRequestImpl.java:2630)
at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:219)
at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:178)
What is going on at the place where this crashes? Is there a way find
out what class it really can't find?
Thanks,
Patrick

What exactly is a wrapper class?

In so far as Integer, Byte, Double et al. are concerned I understand that those wrapper classes are a way to handle primitive types as objects. But I've come across references to wrapper classes in documentation and other technical articles and I don't think I really understand what they are really used for. Why do you need a wrapper class for an object?
Could someone shed me some light on this issue?
Thanks,
John

An instance of a wrapper class holds a pointer to and instance of some other class or interface and provides access to it, typically supplying methods equivalent to all the methods of the underlying type.
The basic wrapper class a functional replacement for the underlying object.
When you're passed an object from some code outside your control you often don't know what exact class it is, or have access to it's class definition.
A wrapper object allows you to modify the functionality of such an object. You can extend the wrapper class, for example, adding extra methods. Or you can modify the methods, for example to provide logging of calls made.
As a concrete example, I have a wrapper class LoggedConnection which wraps a java.sql.Connection object. It also implements java.sql.Connection. If you ask a LoggedConnection for a Statement or PreparedStatement it fetches the appropriate object and returns a wrapped version which logs the SQL and the execution times etc..
My "get me a connection" routine can return either a raw Connection or a LoggedConnection according to whether a SQL log file is provided.
The main program doesn't need to know if it's using a genuine Connection object or the wrapped version.
Part of the definition would look like:
public class LoggedConnection implements Connection {
private Connection wrappee;
public LoggedConnection(Connection con) {
wrapee = con;
public createStatement() throws SQLExeception {
return new LoggedStatement(wrappee.createStatement())
}(Of course this was tedious to write by hand because Connection has so many methods, all of which the wrapper must implement. Later I wrote a java program to generate Wrapper classes).

Wrapper class for HashMap

Why people write Wrapper class for HashMap? Why not directly use the HashMap?

I thought that the term wrapper class is generally
used to signify one class having an instance of
another class inside it. And not one class
deriving from another.
But thats just me.I think that is just you. :)
I consider "wrapping" as having a subset of the functionality of another class. This could be containing or extending, in my opinion.
Consider:
// only partially functional vector for JButtons...
// class containing Vector
public class JButtonVector
Vector vec = new Vector();
public void add(JButton button)
    vec.add(button);
public JButton get(int index)
    if(index >= vec.size() || index < 0)
      throw new IllegalArgumentException(...);
    return (JButton)vec.get(index);
// class extending Vector
class JButtonVector2 extends Vector
public void add(JButton but)
    super.add(but);
public JButton get(int index)
    return (JButton)(super.get(index));
}Problem with the second class is that it also allows adding of regular Objects. That might not be desirable (in this case, it is definitely not).

What is the proper way to code a "wrapper" class?

Basically I want to replace an existing Action with a custom Action, but I want the custom Action to be able to invoke the existing Action.
The following code works fine. I can create a custom Action using the existing action and the text on the button "paste-from-clipboard" is taken from the existing Action. So everything works great as long as the existing Action extends from AbstractAction.
However the Action interface does not support the getKeys() method which I used to copy the key/value information from the existing action to the wrapped action. So if you try to create a button from some class that strictly implements the Action interface the key/value data in the wrapped Action will be empy and no text will appear on the button.
So as the solution I thought I would need to override all the methods in the wrapped Action class to invoke the methods from the originalAction object. That is why all the commented code in the class is there. But then the protected methods cause a problem as the class won't compile.
Do I just not worry about overriding those two methods? Is this a general rule when creating wrapper classes, you ignore the protected methods?
import java.awt.*;
import java.awt.event.*;
import java.beans.*;
import javax.swing.*;
import javax.swing.text.*;
public class WrappedAction extends AbstractAction
     private Action originalAction;
     public WrappedAction(JComponent component, KeyStroke keyStroke)
          Object key = getKeyForActionMap(component, keyStroke);
          if (key == null)
               String message = "no input mapping for KeyStroke: " + keyStroke;
               throw new IllegalArgumentException(message);
          originalAction = component.getActionMap().get(key);
          if (originalAction == null)
               String message = "no Action for action key: " + key;
               throw new IllegalArgumentException(message);
          // Replace the existing Action with this class
          component.getActionMap().put(key, this);
          // Copy key/value pairs to
          if (originalAction instanceof AbstractAction)
               AbstractAction action = (AbstractAction)originalAction;
               Object[] actionKeys = action.getKeys();
               for (int i = 0; i < actionKeys.length; i++)
                    String actionKey = actionKeys.toString();
                    putValue(actionKey, action.getValue(actionKey));
     private Object getKeyForActionMap(JComponent component, KeyStroke keyStroke)
          for (int i = 0; i < 3; i++)
          InputMap inputMap = component.getInputMap(i);
          if (inputMap != null)
                    Object key = inputMap.get(keyStroke);
                    if (key != null)
                         return key;
          return null;
     public void invokeOriginalAction(ActionEvent e)
          originalAction.actionPerformed(e);
     public void actionPerformed(ActionEvent e)
          System.out.println("custom code here");
          invokeOriginalAction(e);
     public void addPropertyChangeListener(PropertyChangeListener listener)
          originalAction.addPropertyChangeListener(listener);
     protected Object clone()
          originalAction.clone();
     protected void firePropertyChange(String propertyName, Object oldValue, Object newValue)
          originalAction.firePropertyChange(propertyName, oldValue, newValue);
     public Object[] getKeys()
          return originalAction.getKeys();
     public PropertyChangeListener[] getPropertyChangeListeners()
          return originalAction.getPropertyChangeListeners();
     public Object getValue(String key)
          return originalAction.getValue(key);
     public boolean isEnabled()
          return originalAction.isEnabled();
     public void putValue(String key, Object newValue)
          originalAction.putValue(key, newValue);
     public void removePropertyChangeListener(PropertyChangeListener listener)
          originalAction.removePropertyChangeListener(listener);
     public void setEnabled(boolean newValue)
          originalAction.setEnabled(newValue);
     public static void main(String[] args)
          JTextArea textArea = new JTextArea(5, 30);
          JFrame frame = new JFrame("Wrapped Action");
          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          frame.add(new JScrollPane(textArea), BorderLayout.NORTH);
          frame.add(new JButton(new WrappedAction(textArea, KeyStroke.getKeyStroke("control V"))));
          frame.pack();
          frame.setLocationRelativeTo( null );
          frame.setVisible( true );

I can't get the PropertyChangeListener to fire with any source. Here is my test code. Note I am able to add the PropertyChangeListener to the "Paste Action", but I get no output when I add it to the WrappedAction. I must be missing something basic.
import java.awt.*;
import java.awt.event.*;
import java.beans.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.text.*;
public class WrappedAction3 implements Action, PropertyChangeListener
     private Action originalAction;
     private SwingPropertyChangeSupport changeSupport;
      * Replace the default Action for the given KeyStroke with a custom Action
     public WrappedAction3(JComponent component, KeyStroke keyStroke)
          Object actionKey = getKeyForActionMap(component, keyStroke);
          if (actionKey == null)
               String message = "no input mapping for KeyStroke: " + keyStroke;
               throw new IllegalArgumentException(message);
          originalAction = component.getActionMap().get(actionKey);
          if (originalAction == null)
               String message = "no Action for action key: " + actionKey;
               throw new IllegalArgumentException(message);
          // Replace the existing Action with this class
          component.getActionMap().put(actionKey, this);
          changeSupport = new SwingPropertyChangeSupport(this);
        originalAction.addPropertyChangeListener(this);
        addPropertyChangeListener(this);
      * Search the 3 InputMaps to find the KeyStroke binding
     private Object getKeyForActionMap(JComponent component, KeyStroke keyStroke)
          for (int i = 0; i < 3; i++)
              InputMap inputMap = component.getInputMap(i);
              if (inputMap != null)
                    Object key = inputMap.get(keyStroke);
                    if (key != null)
                         return key;
          return null;
     public void invokeOriginalAction(ActionEvent e)
          originalAction.actionPerformed(e);
     public void actionPerformed(ActionEvent e)
          System.out.println("actionPerformed");
// Delegate the Action interface methods to the original Action
     public Object getValue(String key)
          return originalAction.getValue(key);
     public boolean isEnabled()
          return originalAction.isEnabled();
     public void putValue(String key, Object newValue)
          originalAction.putValue(key, newValue);
     public void setEnabled(boolean newValue)
          originalAction.setEnabled(newValue);
     public void xxxaddPropertyChangeListener(PropertyChangeListener listener)
          originalAction.addPropertyChangeListener(listener);
     public void xxxremovePropertyChangeListener(PropertyChangeListener listener)
          originalAction.removePropertyChangeListener(listener);
     public void addPropertyChangeListener(PropertyChangeListener listener)
        changeSupport.addPropertyChangeListener(listener);
    public void removePropertyChangeListener(PropertyChangeListener listener)
        changeSupport.removePropertyChangeListener(listener);
     public void propertyChange(PropertyChangeEvent evt)
         changeSupport.firePropertyChange(evt.getPropertyName(), evt.getOldValue(), evt.getNewValue());
     public static void main(String[] args)
          JTable table = new JTable(15, 5);
          WrappedAction3 action = new WrappedAction3(table, KeyStroke.getKeyStroke("TAB"));
          action.addPropertyChangeListener( new PropertyChangeListener()
               public void propertyChange(PropertyChangeEvent e)
                    System.out.println(e.getSource().getClass());
          action.putValue(Action.NAME, "name changed");
          Action paste = new DefaultEditorKit.PasteAction();
          paste.addPropertyChangeListener( new PropertyChangeListener()
               public void propertyChange(PropertyChangeEvent e)
                    System.out.println(e.getSource().getClass());
          paste.putValue(Action.NAME, "name changed");
}

What are the uses of Void wrapper class?

Hi,
Similar to other Wrappers, Void is a wrapper class for the primitive ' void ' . We all know that Void is a final class , we can't instantiate it.
My Question is what are the uses of Void?
thanks,

kajbj wrote:
I have at times used it in reflection and jmx.I have used them with SwingWorker if I didn't have anything interesting to return. There is also an example in the tutorial: [http://java.sun.com/docs/books/tutorial/uiswing/concurrency/simple.html]

Developing the Wrapper class to log the message in XI server

Hi All,
We are trying to develop wrapper class on the SAP Logging API, in that I am unable to log the message in the log file(whose path is mentioned in the properties file).
We use this for storing when exception raised during message transformation due to certain error conditions...
Procedure:
My Wrapper class will take the parameters from Property file and store/log the message in the specified location,
This is working outside of XI environment
Please suggest how to make to work in XI environment
Also suggest do I need to do any configurations in SAP web As
Thanks,
venu.

HI,
With the above blog ref by Michal , see the below links also,
/people/alessandro.guarneri/blog/2006/03/27/sap-xi-lookup-api-the-killer
/people/amjad-ali.khoja/blog/2005/12/16/slaw-a-new-logging-tracing-framework-for-xi
/people/amjad-ali.khoja/blog/2006/02/07/using-dom4j-in-xi--a-more-sophisticated-option-for-xml-processing-than-sap-xml-toolkit
Also my be useful..
/people/community.user/blog/2007/01/09/enterprise-soa-explorations-reflections-on-database-integration
/people/anne.tarnoruder/blog/2006/10/26/reusing-code-with-pdk-for-net
/people/piers.harding/blog/2006/05/18/ruby-on-rails-with-ajax
Regards
Chilla

How to get SDKODBC Wrapper class for indesign cs3

Hi,
I have to implement the mysql database with my indesign plugin. I didn't have a SDKODBC Wrapper class. Can any one say how to get SDKODBC Wrapper class from adobe.
Regards,
saravanan.

I doubt if change documents are generated for SE78 transaction.
For list of change documents defined, please check table: TCDOB.
Hope this helps.
Kind Regards
Eswar

What is the advantage of using Wrapper Classes ?

Hi friends,
I am happy to join Java/J2EE tech. My project is scaled over the network. MVC-II struts, EJB based architecture, we are using.
We are asked to use Wrapper Classes in in Java programs and not the primitive data types. I could not understand the reason.
Pls tell me what is the advantage of using Wrapper Classes over the primitive data types ?
means Integer instead of int, etc....

Hi friends,
I am happy to join Java/J2EE tech. My project is
scaled over the network. MVC-II struts, EJB based
architecture, we are using.
We are asked to use Wrapper Classes in in Java
programs and not the primitive data types. I could
not understand the reason.
Pls tell me what is the advantage of using Wrapper
Classes over the primitive data types ?
means Integer instead of int, etc....I am not sure why use Integer over int; but Wrapper classes are used to remove coupling between classes and create one hand doesn't know what the other hand does effect.
for example:
when you have a SFTP java package but doesn't do everything that your application needs to do in one step and you need to do sftp stuff at many places in your application, it would be wise not to use SFTP java package directly from all the classes that need to do sftp stuff. Because if you were to change the SFTP package later due to say some bug fix or newer version or ... you would have to go and modify all the classes that had sftp stuff to update.
Instead you could write a custom sftp wrapper that handles all the sftp stuff for your application needs and that wrapper deals with the SFTP java package. So all the classes don't need to know which SFTP java package is being used only the custom-wrapper needs to know.

How to write a wrapper class

I am new to the concept of wrapper classes. I have a small spell checker program that I need to access via a servlet by passing a string in and getting a string out with spelling suggestions. I could really use some advice on how to write a servlet that would do such a thing. TIA

grin1dan wrote:
I am new to the concept of wrapper classes. I have a small spell checker program that I need to access via a servlet by passing a string in and getting a string out with spelling suggestions. I could really use some advice on how to write a servlet that would do such a thing. TIABasically, a wrapper class is a class that "wraps" another - otherwise referred to as a "HAS-A" relationship (as opposed to a sub-class, which involves an "IS-A" relationship). It does this by including an instance of the wrapped class as one of its fields.
In many cases, wrapping is actually superior to inheritance.
I don't know how this fits with your servlet, but - assuming that your SpellChecker is implemented as a class - all you need to do is have your servlet define a "spellchecker" field; perhaps something like:
private final SpellChecker spellCheck = new SpellChecker();Probably worth reading up on though. Google "wrapper classes" and "forwarders".
Winston

Apache comons logging implemented it with a wrapper classes around

hi friends,
i have an interesting (unsually )problem regaurding apache commons logging, i am using three classes .
one is the logger class where i instantiate the logging instance ie Log log = LogFactory .getLog("some name");
then there is a class called LFactory where i use i hashMap to store the various different logger created or to access the different logger for the hashmap
then the last i have i LoggerAccessor class which links the LFactory.
as u all now that the logger will give the line number of the class where we use the log instance ( Log log)..... but as i am using a wrapper classes around the actually log instance.
in any class where i require the logging to be done.. i used my LoggerAccessor. so instead of giving me the Actuall Classname,methodname,and line number of the class where i give logging statements. I get the name of my class where i have created the instance and specially the line number of the class where the instance is created....( means my first class).
i want to get the name,method,linenumber of the class where i have added logging statements
please find me the solution for it.....
thanks

Good Question Nutan !! But i don't have answer !! Hope someone else will answer this !

Wrapper classes/ instance variables&methods

can anyone provide me additional information on the wrapper classes.
In addition, could someone please provide an explination of the- instance and class (variables+methods)

Every primitive class has a wrapper class e.g.
int - Integer
float - Float
long - Long
char - Character
etc. When a primitive is wrapped it becomes an object and immutable. Primitives are generally wrapped (either to make them immutable) or to be able to add them to the collections framework(sets, maps, lists which can only take objects, not primitives).
An instance variable is a variable that each copy of the object you create contains, as is an instance method. Each instance you create (each copy of the object) contains its own copy of the variable and method.
A class variable and method means that no matter how many objects you create, there will be one and only one copy of the variable and method.
Hope this helps. Also see the java tutorial.

Could not load mediaLib accelerator wrapper classes. Continuing in pure Jav

Can anyone provide an explanation/solution to the following error message:
"Could not load mediaLib accelerator wrapper classes. Continuing in pure Java mode."

This problem seems to occur if only the JAI JAR files are installed without the native DLL's. Is there some property that can be passed in to JAI so that it doesn't look for the DLL's? The lookup is causing quite a delay in initial server response time. We don't want to include the DLL's since they are a big pain for our customers to install and the performance issue is not a concern.
Thanks for any help!
-Matt

Is there an efficient wrapper class for reading binary data in cocoa/iPhone

Hi,
I need to read a data from a binary file in my iPhone application. What is the best way to do it? Is there an efficient cocoa wrapper class for this purpose?
Thanks,
Nava

A char is a 16-bit unsigned value - depending on what you want, it may help.
I don't understand your reluctance to mask off the upper 16 bits of an integer; all it requires is a single bitwise 'and' statement. I challenge you to measure the impact of such a statement on your program.

Advantages and disadvantages of wrapper classes

Hi ,
will you please let me know what are the advantages and disadvantages of wrapper classes.
please do needful ASAP.
thanks in advance

Hi Anil,
Wrapper classes are classes that allow primitive types to be accessed as objects.
Refer the foll Link:
http://www.cs.wustl.edu/~schmidt/PDF/Reactor1-93.pdf
http://whitepapers.silicon.com/0,39024759,60104914p,00.htm
Regards,
Sunil

Definition to a wrapper class

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