Basic questions on Java platform and JDK

Hello,
I have a few questions, might be very elementary.
Please clarify.
(Tried in "New to Java" Forum....but did not get much
response)
What I know is : A "Java Platform" is composed of the
Java language, a JVM, and the APIs. There is a spec.
for the language, and another spec for JVM. Now, are
there spec.s for the API as well ?There are some specs which the API fulfills (see your other thread for examples). But not all classes in the API is covered by a specification.
Another related question is : where exactly do the
various flavours of the Java Platform (J2SE, J2EE,
J2ME) differ? What do you mean? There are different specifications for the different editions / flavours. They can differ both in API and VM.
I have seen some explanations where it
seems to say that these editions have been created to
give more appropriate support to different areas of
applications. But, what I know to know is : what
exact component of the Java Platform differs from one
edition to another - language features, or the JVM,
or the APIs ? All of them can differ. (Does it matter?)
Another question : what is it, that differs from one
JDK release to another, say from J2SE 1.3 to J2SE
1.4.0 ? Read the relese notes. New classes, some new methods, and also minor changes to the language. New JSRs had also been implemented.
I think the Java language spec itself rarely changes
(Is this right?). Depends on what you mean by rarely
It changed from 1.0 to 1.1, from 1.3 to 1.4 and from 1.4 to 1.5.
Also the VM spec rarely changes (is
this correct ?).It has changed a few times.
So, is it that only the APIs change
(new classes added, old ones modified, etc.) ?No
Kaj

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The reason I asked because I did create an application which has a frame, a panel and couples of buttons, text fields then ftp it to Unix Solaris, when I ran it with jre command, I got the following message:
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Take Care,
Rob
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Hi there,
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Great Indian Developer Summit 2010 u2013 India's Biggest Polyglot Conference and Workshops for IT Software Professionals
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A Saltmarch Media Press Release
E: info AT saltmarch dot com
Ph: +91 80 4005 1000
Edited by: wonkim785 on Apr 14, 2010 8:23 AM

Im not sure if this is the right place to post this, but anyway thanks for the info :)

Basic questions about Bigdata, NOSQL and Hadoop

Hi,
I've basic questions related to Bigdata. (I've googled it but still wants to confirm with experts)
Please correct me if I am wrong on below.
1) As far as I know big data is collection of unstructured data. Even we can store relational data as well.
2) NOSQL is an Oracle product to handle bigdata (un structured data and relational data as well)
3) Hadoop is the only one frame work which is avilable in market to manage the bigdata.
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Cheers,
Suri

Hi Suri,
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Hope this helps,
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Questions about Java Servlets and JSP

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Hi, Steve ...has to be frustrating! But do not despair.
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WEB-INF should look:
WEB-INF
classes
org
servlets
MyServlet.class
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<servlet-mapping>
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</web-app>Now, once the container starts (Tomcat?), you should be able to see that servlet in:
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The D-Link modem/router.
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Hi bshannon,
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thanks.
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:) jen

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You must provide XSLT stylesheeds to specify transformations (1), (2),
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http://java.sun.com/xml/jaxp/dist/1.1/docs/tutorial/xslt/index.html.

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Thank you

1.    String[] numString = {"1","2","345678","9","abc"};
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Question About Java Threads and Blocking

I'm helping someone rehost a tool from the PC to the Sun. We're using the Netbeans IDE and the Java programming language. I took a Java course several years ago, but need some help with something now. We're developing a front-end GUI using Swing to allow users to select different options to perform their tasks. I have a general question that will apply to all cases where we run an external process from the GUI. We have a "CommandProcessor" class that will call an external process using the "ProcessBuilder" class. I'm including the snippet of code below where this happens. We pass in a string which is the command we want to run. We also instantiate a class called "StreamGobbler" my coworker got off the Internet for redirecting I/O to a message window. I'm also including the "StreamGobbler" class below for reference. Here's the "CommandProcessor" class:
// Test ProcessBuilder
public class CommandProcessor {
public static void Run(String[] cmd) throws Exception {
System.out.println("inside CommandProcessor.Run function...");
Process p = new ProcessBuilder(cmd).start();
StreamGobbler s1 = new StreamGobbler("stdin", p.getInputStream());
StreamGobbler s2 = new StreamGobbler("stderr", p.getErrorStream());
s1.start();
s2.start();
//p.waitFor();
System.out.println("Process Returned");
Here's the "StreamGobbler" class:
import java.lang.*;
import java.io.*;
// Attempt to make the output of the process go to the message window
// as it is produced rather that waiting for the process to finish
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String name;
InputStream is;
Thread thread;
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this.is = is;
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thread = new Thread (this);
thread.start();
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try{
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BufferedReader br = new BufferedReader(isr);
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String s = br.readLine();
if (s == null) break;
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//messageWindow.writeToMessageArea("[" + name + "]" + s);
is.close();
catch(Exception ex){
System.out.println("Problem reading stream" + name + "...:" + ex);
ex.printStackTrace();
The "CommandProcessor" class calls two (2) instances of the "StreamGobbler" class, one for "stdin" and one for "stderr". My coworker discovered these are the 2 I/O descriptors that are needed for the external command we're running in this case. We're actually called the Concurrent Versions System (cvs) command from the GUI. Here's what we need it to do:
We want to display the output real-time as the external process is executing, but we want to block any actions being performed on the GUI itself until the process finishes. In other words, we want to show the user any generated output from the process, but don't want to alllow them to perform any other actions on the GUI until this process has finished. If we use the "waitFor()" function associated with a process, it blocks all external process output until the process has completed and then spews all the output to the screen all at once. That's NOT what we want. Also, if we don't use the "waitFor()" function, the code just continues on as it should, but we don't know how to block any actions on the GUI until this process has finished. My coworker tried the following code, but it also blocked any output until the process had finished:
while (s1.thread.isAlive() || s2.thread.isAlive())
// We really don't do anything here
I'm pretty sure we have to use threads for the output, but how do we instantly show all output and block any GUI actions?
Thank you in advance for your help!

You're talking about a GUI, but there's nothing in that code which is putting events into the GUI update thread. You also say that nothing happens to the GUI until the CommandProcessor.Run() method returns if you wait for the process.
This implies that you're calling CommandProcessor.Run() in an ActionListener. This will block the GUI thread until it completes.
I was going to explain what to do, but a quick Google informed me that there's a new class which is designed to help in these situations SwingWorker (or as a [separate library|https://swingworker.dev.java.net/] if you're not up-to-date yet).

Some basic questions about foriegn key , and relationships.

Hi
Thank you for reading my post
I read some documents about foreugn key and tables relation ships.
but i still can not understnad some stuff.
1-when we have a foreign key , we have two tables that we want to relate them together
in a way that one of ? table columns forced to be a value from ?? table column.
what is name of those two tables , i saw , child-parent , ..... which confuse me.
can some one please tell me correct name of those two tables ?
2-some times we need some kind of master details relation like :
one-to-many : i this case MANY table will have a column to point a record in ONE table , can this relation be a foreign key relation ?
3-we can achieve many-to-many relation only by using a helper table to host both tables primary keys in a record to relate them together.
can you point me to some resources that help me to find answers to this questions ?
or explain them to me ?
thank you for your time.

These are critical database basics that you need to understand. I would seriously recommend getting some study in, because proper relational database design relies on the basic principle of data and relationships and a process called normalization.
In reality, you only really need one gigantic table to host data. It would include everything you would want to know about something - let's take a sales order for example. You would have to record the customer's name, address, etc. along with every item they ordered, etc. You would have a HUGE table full of data that appeared over and over and over again. This is bad design for two basic reasons: it is difficult to query, and it is very easy to have minor mistakes like capitalization or alternate spellings that prevent things from matching up properly. For example, let's say Bob orders 40 widgets and 40 digits. In our hypothetical table, we could put it in as Bob - 40 widgets and Robert - 40 digits. See how confusing this can get even in a simple example? And let's say you wanted to correct all of Robert's orders to say Bob and you found out there were 40 orders from "Robert" How would you know which ones to change?
The process of normalization helps to reduce the chance for these types of errors in addition to creating a good basis for indexes. You normalize the data by creating sets of parent/child tables with a "key" value to match them. In our hypothetical situation, you could create a table for orders and a table for customers. In the customers table you give all the detail for the customer in one place, and you assign each customer a unique number or ID. In the orders table we add the customer ID (NOT the name) and we ensure that we are getting the customer we want, in addition to saving a lot of space and eliminating redundancy. In our example, the customers table is the "parent" table and the orders table is the "child" table. The child table references the unique entries in the parent table via that id. That reference is referred to as a foreign key. The foreign key in the child table points back to the original and complete record in the parent table and eliminates the redundancy of keeping all that extra data for every order. Foreign keys in child tables always refer to a primary/unique key in the parent field.
That help?

Very basic questions on JAX-RPC and wscompile

Hello,
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mypackage.structures.segments.AWhen generating the server stub, I am getting:
Duplicate type name "{urn:mynamespace}A" for java type "mypackage.structures.segments.A" found.
Is there a way to tell wscompile to keep the class package name for every class when generating the wsdl? Or is it always building all the classes together in the package specified in the service/packageName within the configuration xml file?
Thanks a lot in advance for any help.

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