NIIT Technical Trainers @ Kerala

Breaking News:Naming a Java File

2009-10-30T06:09:00.000-07:00

I think atleast for some of us, this would be a breaking news.If not just forget this blog.

Normally, we say that "A java file must be named by the class name containing the main method."

If any of you have this opinion, I think i just found out that its wrong.

Its not a rule, its a convention in order to make thinks easier.

If u check niit's slide java funda->slide 2B slide no 12 point no 2-i think its wrong.

It must be "Conventionally, A java file is named by the class name containing the main method."

Alternatively, "A java file must be named by the class name containing the public modifier(if there is a public class), but ofcourse there should be only one class with public modifier.If there is more than one public class, it would result in an error."

Now, why is it said "conventionally"?

Say u have 2 classes A and B.if B contains the main method, u can name the file anything.But when wont be able to run it directly through editplus or other editors.In cmd u've to run as follows.

java B

So for convenience, we name the file as the class name containing the main method.

Those teaching java batches, please make a note of this.

To know more, please feel free to write back.

Thank You

Security Demo Sites

2009-09-08T23:34:00.000-07:00

Hi friends,

During our CJEV2 training Arafath had given us some site names which uses basic authentication,diagest authentication and all.If u have those site lists pls give me that.

Shinie Mathew

A Brief History of Java and JDBC

2009-08-14T03:40:00.000-07:00

Check the links guys..
Really nice
http://blogs.datadirect.com/2009/07/a-brief-history-of-java-and-jdbc.html
And this too...
http://www.youtube.com/watch?v=WAy9mgEYb6o

Spell check URL

2009-06-16T02:43:00.000-07:00

hi friends ,

pls give me the url of google spellcheck(arafath gave us during the training)

Shinie

Java Everywhere!!!

2009-05-30T23:11:00.000-07:00

Hey guys!!
The blog is getting dead!
So I decided to add some fun..
I was preparing a small presentation on Java and I needed some fun way to emphasize the point 'Java Everywhere'. And I found this interesting video at Channel Sun. And there are a lot of other videos there too..
http://channelsun.sun.com/video/java+everywhere/1717895934

And this one's a bit old!! But I loved the bald guy!!!
May be I should also shave my head!!!!!!!!!!

Prob with JSp

2009-04-06T00:01:00.000-07:00

Hi friends,

when I am trying to exceute JSp the following error comes.I have installed jdk and AppServer from tirm and set the path properly itself.for ur reference i am giving my path too.friends pls help
Error
HTTP Status 500 -
type Exception report
message
description The server encountered an internal error () that prevented it from fulfilling this request.
exception org.apache.jasper.JasperException: Unable to compile class for JSP
No Java compiler was found to compile the generated source for the JSP.
This can usually be solved by copying manually $JAVA_HOME/lib/tools.jar from the JDK
to the common/lib directory of the Tomcat server, followed by a Tomcat restart.
If using an alternate Java compiler, please check its installation and access path.
org.apache.jasper.compiler.DefaultErrorHandler.javacError(DefaultErrorHandler.java:127)
org.apache.jasper.compiler.ErrorDispatcher.javacError(ErrorDispatcher.java:348)
org.apache.jasper.compiler.Compiler.generateClass(Compiler.java:424)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:464)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:448)
org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:551)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:300)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:301)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:248)
javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
java.lang.reflect.Method.invoke(Method.java:324)
org.apache.catalina.security.SecurityUtil$1.run(SecurityUtil.java:284)
java.security.AccessController.doPrivileged(Native Method)
javax.security.auth.Subject.doAsPrivileged(Subject.java:500)
org.apache.catalina.security.SecurityUtil.execute(SecurityUtil.java:306)
org.apache.catalina.security.SecurityUtil.doAsPrivilege(SecurityUtil.java:200)

path settings

path=.;C:\Program Files\j2sdk_nb\j2sdk1.4.2\bin;C:\Sun\AppServer\bin;
classpath=.;C:\Program Files\j2sdk_nb\j2sdk1.4.2\lib;C:\Sun\AppServer\lib\j2ee.jar;
JAVA_HOME=C:\Program Files\j2sdk_nb\j2sdk1.4.2;
J2EE_HOME=C:\Sun\AppServer;

Shinie Mathew

RMI Dooubts

2009-03-01T06:14:00.000-08:00

Okay guys... Simple question again. But its bugging me. This time, its about RMI.

I need this setup. Three nodes A, B and C. The RMI Server must run in Node A. The RMI Client in Node B and node C should have the RMI Registry. I tried this setup and whenever I try to bind the remote object from the server, I am getting an Exception. Am trying to bind it like this,

Naming.rebind("rmi://192.168.1.25/Server",obj);

192.168.1.25 is the ip address of the node where RMI Registry is running.
I don't remember the exception. Another thing I noted when I went through the Java API was this part..

rebind

public static void rebind(String name,
                        Remote obj)
                 throws RemoteException,
                        MalformedURLException

Rebinds the specified name to a new remote object. Any existing binding for the name is replaced.

Parameters:: name - a name in URL format (without the scheme component); obj - new remote object to associate with the name
Throws:: MalformedURLException - if the name is not an appropriately formatted URL; RemoteException - if registry could not be contacted; AccessException - if this operation is not permitted (if originating from a non-local host, for example)

Why though?

Hmm Some more help please!!!

2009-02-18T01:29:00.000-08:00

Hi guys!!!
Glad to see this thing is going on well!!!
Also try to keep contacts through phone also!!!
Any ways, here is a small problem I just faced..
May be I am just a complete noob!!! :(

Here is the program

class Base
{
String msg;

public Base(String msg)
{
this.msg=msg;
//Just for the sake of overloading the default constructor!!!!
}

public void display()
{
System.out.println("Base");
}
}

class Sub extends Base
{
public void display()
{
System.out.println("Sub");
}

public static void main(String args[])
{
Sub obj=new Sub();
obj.display();
}
}

This thing works fine if the constructor of the Base class is put in comments and also works if I add no-argument constructor to it! Any explanations for this. I've no idea!! May be its because my foundations are a bit shaky!!!

PS:
Hey Arafath!!! How are you doing?? Went to China again? Say hi to Hu Jintao!!

HashTable

2009-02-10T21:09:00.000-08:00

Hi Trainers,
Here is a question!
There is a program about Hashtable in 1A.31(PAS).
In that program i'm adding 4 names along with some double values into the hashtable, but when asked to display the values, its not displayed in the order in which i've entered values to the table.For instance, i've added names in the order Albert,Tom,Todd and Smith.
The output shows Tom,Albert,Todd and Smith.
Do you have any idea why the order is messed up, or do you actually find any sequence??????????

Assertion!!! How can I explain that to my students?

2008-11-07T07:10:00.000-08:00

Well, the blog has been up and running for some time now with ZERO posts.. So I am taking the liberty to be the first one to post and that too a query.. I need some tips on how to explain the concept of assertion and the need.. Guys (and gals too), help me!!!