Simple Java Coding Question

I know this is a simple question, but I can't search for the answer to this because it involves syntax that Google and the like don't seem to search for..
I am trying to figure out some Java code that I have found. I would like to know what:
a[--i] and a[++j] mean.
My first thought was that they meant to look at the position in the array one less (or more) than i (j). But that doesn't seem to be the case. A is an array of Strings, if that matters...
Thanks for you help.

muiajc wrote:
I know this is a simple question, but I can't search for the answer to this because it involves syntax that Google and the like don't seem to search for..
I am trying to figure out some Java code that I have found. I would like to know what:
a[--i] and a[++j] mean.
It mean increase/decrease the int i/j by 1. This is done before it gets you the value of a[]. for example if i=5 and you said a[--i] it is really a[4] and i is now equal to 4;

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Simple Java EJB question.

When it comes to EJB v3 Remote and Local interfaces,
(With JBoss EJB Container Software in mind, for this question,)
-Does the Remote interface for the EJB include method signatures from the Bean class
-that are to be seen
-that are to be hidden?
-Does the Local interface for the EJB include method signatures from the Bean class
-that are to be seen
-that are to be hidden?
Which is which for
-EJB 2.1 ?
-EJB 3.x ?
- is EJB 3.x reverse compatible in that it allows use of the javax.ejb.* interfaces,
and would accept a EJB 2.1 approach, or does it force one to use Annotations
exclusively?
Edited by: Zac1234 on Jul 21, 2010 5:21 PM

muiajc wrote:
I know this is a simple question, but I can't search for the answer to this because it involves syntax that Google and the like don't seem to search for..
I am trying to figure out some Java code that I have found. I would like to know what:
a[--i] and a[++j] mean.
It mean increase/decrease the int i/j by 1. This is done before it gets you the value of a[]. for example if i=5 and you said a[--i] it is really a[4] and i is now equal to 4;

Simple Java Sound Question...

Can I draw waveforms while capturing data? If yes, how. If no, why.
Thanks. I need the answer ASAP, please help.

Hi nfactorial,
Can I draw waveforms while capturing data?If you would like to do that in Java you would need to know about how to use the Java language in general and especially about the Java Sound and Java2D APIs.
If yes, how.It would be too much to explain to answer such a general question. A general answer is, you need to use the Java Sound API to capture the data for which a waveform should be drawn. The Sound API delivers data as a stream of bytes typically encoded in pulse coded modulation (PCM) format. The data stream has digital samples each representing a level of sound pressure for a certain point in time. The stream of samples in the amplitude/time domain need to be transformed to a spectrum of samples in the amplitude/frequency domain, i.e. a number of PCM samples need to be mapped to the frequencies that should be displayed. This is done with the fast fourier transformation algorithm. Each set of amplitude/frequency values can then be displayed as a waveform by using some line drawing logic. The entire process would need to run constantly, i.e. as bytes are received from the sound data stream transformation and drawing is triggered.
Related readings:
Java Tutorial
http://java.sun.com/docs/books/tutorial/
Java Sound Documentation
http://java.sun.com/j2se/1.5.0/docs/guide/sound/index.html
Java Sound API Programmer's Guide
http://java.sun.com/j2se/1.5.0/docs/guide/sound/programmer_guide/contents.html
Java Sound Resources
http.//www.jsresources.org
Java 2D Graphics Tutorial
http://java.sun.com/docs/books/tutorial/2d/index.html
Wikipedia on fast fourier transformation
http://en.wikipedia.org/wiki/Fast_fourier_transform
HTH
Ulrich

Plzzz write prog to this simple java threads question

Write a program in C to create four processes. The original processes creates
two children before it prints out "PARENT". The children processes print
"CHILD1" and "CHILD2" respectively. The first child process creates a child
process that prints out "GRANDCHILD".
Note: The output must be guaranteed to print out in the following order each
time it is executed:
GRANDCHILD
CHILD2
CHILD1
PARENT
a. Write the program using C or C++ and forks to create the children processes.
b. Write a second program using Java and Threads for the children processes.
The output statements for CHILD1, CHILD2 and GRANDCHILD must come from print
statements in the run method of the thread.

Most people here will not do your homework for you. If you post a reasonable question that shows you've made some effort, and what the results of that effort were, and provides details about what parts you're having trouble with, then somebody will probably provide guidance so that [you can complete the work.

Simple Java SDK question for server group assignment

I have a snippet of code below in which I am trying to apply the setProcessingServerGroup() and setProcessingServerGroupChoice() methods to my report object. My question should be relatively simple: I believe I need to cast(?) my iObject report object to iProcessingServerGroupInfo per the API in order to use the setProcessingServerGroup() and setProcessingServerGroupChoice() methods, but I'm not sure how to do so.
Can someone please advise how to cast my iObject to iProcessingServerGroupInfo?
Thanks in advance...
Code:
IInfoObject iObject = (IInfoObject) childReports.get(i);
int sgID_view = Integer.parseInt(serverGroupID_view);
int sgPref_view = Integer.parseInt(serverGroupPref_view);
!!!!! CONVERSION / CAST NEEDED HERE !!!!!
iProcessingServerGroupInfo.setProcessingServerGroup(sgID_view);
iProcessingServerGroupInfo.setProcessingServerGroupChoice(sgPref_view);

To followup, I've been able to cast to IShedulingInfo in order to use the setServerGroup() and setServerGroupChoice() methods successfully:
IInfoObject iObject = (IInfoObject) iObjects.get(i);
ISchedulingInfo iSchedulingInfo = iObject.getSchedulingInfo();
iSchedulingInfo.setServerGroup(427);
iSchedulingInfo.setServerGroupChoice(2);
But I don't know how to perform the cast to be able to access the setProcessingServerGroup(), sterProcessingServerGroupChoice() methods.
Any help appreciated.
Thanks!

Simple java architecture question

This should be a simple question to answer but I haven't been able to find a good answer.
I have an application that establishes a network connection with a server and registers event listeners on that connection.
What I want to do is find a way without a busy-wait/while loop to keep the main() thread running so that the listeners can do their job.
Here is a sample of what I've got:
public static void main(String[] args)
SomeConnection conn1 = null;
try
conn1 = new SomeConnection("someaddress");
TrafficManager tm = conn1.getTraffictManager();
TrafficHandler th = tm.createTraffichandler(new MessageListener()
                    public void processMessage(Message message)
                         System.out.println("Received: " + message.toString());
     catch (Exception e)
          e.printStackTrace(System.out);
     conn1.disconnect();
The problem is that the application doesn't stay running to respond to traffic coming across the connection.
Any guidance would be appreciated.
Thanks

Well, what is the job of the MessageListener if it isn't to listen for messages? And apparently it isn't doing that because your application terminates.
Bear in mind that I don't have any idea how any of those four classes work, or even how they are supposed to work. So let me just quote this line from the API documentation of the Thread class which says when your application will terminate:
"All threads that are not daemon threads have died, either by returning from the call to the run method or by throwing an exception that propagates beyond the run method."
That must be the case in your application.

Simple Java Array Question

// This is how I was taught to make a simple array. You have to define the size first.
String [] test1 = new String[4];
test1[0] = "1";
test1[1] = "2";
test1[2] = "3";
test1[3] = "4";
out.println(test1[0]);
out.println(test1[1]);
out.println(test1[2]);
out.println(test1[3]);
//If the size is not defined in this second example, why does it still work?
String [] test2 = {"1","2","3","4"};
out.println(test2[0]);
out.println(test2[1]);
out.println(test2[2]);
out.println(test2[3]);
They both produce the same results.

// This is how I was taught to make a simple array.
You have to define the size first.
String [] test1 = new String[4];
test1[0] = "1";
test1[1] = "2";
test1[2] = "3";
test1[3] = "4";
out.println(test1[0]);
out.println(test1[1]);
out.println(test1[2]);
out.println(test1[3]);
//If the size is not defined in this second example,
why does it still work?
String [] test2 = {"1","2","3","4"};
out.println(test2[0]);
out.println(test2[1]);
out.println(test2[2]);
out.println(test2[3]);
They both produce the same results.Umm..the size is just as well defined in your second as in your first...it is a four element array.
The second way is akin to the first...also
String[] s = new String[]{"Hello","I","contain","five","elements"};
System.out.println(s[5]); Will compile..you will get a run-time ArrayIndexOutOfBoundsException (it is a 5 element array, 0-4, but java will not assume that the variable s is not changed between those two lines of code)..
Array index/boundary checking is done at run-time, not compile-time.
In fact:
String[] s;
//let's say up in the program
//and
public void printS(int i)
System.out.println(s);
Will also compile...and if something else happens to set s as a 10 element String array:
printS(9);would work
~David

Simple java pgm - question

Hallo,
to the following pgm I had question:
static void printPrimes (int max) (= wavy bracket;
boolean(should be angular brackets) sieve = new booolean (angular br max+1
angular br)
int i,j;
for (i=2; i = max;i++)sieve(angluarbr i angular br)= true
i= 2
while (i= <= max;) (=wavy bracket Out.println (i+ " "); // is prime
for (j=i; j <= j+i) sieve(angular br j angularb.) = false;
while (i <= maxAmpersandAmpersand !sieve (angular br angular br)I++;
) wavy br ) wavy br.
I hope this is still kind of readable.
Q's are:
after the first "for" there is a new i=2, which seems to staty at 2 all the time; the following while does not change this value ( the beginning for i++ does not change this) and so seems to print 2 at all times (??)
then the inner loop seems to count up all the doubbles of the new prime number and thrwoes it out as false at the end of it;
the i values (increased with i++ seemsto refere at all times to the unit numbers and only indirect to the un it values, which are written/ assigned to it (??)
I seem to wonder how the pgm can print out anythings else the 2's.
I would appreciate any help to that.
ml
griz

I hope this is still kind of readable.No, it's not. http://forum.java.sun.com/help.jspa?sec=formatting
Why are you omitting the braces and brackets? And why don't you type "program"? Aren't we worth the additional time it takes?
Q's are:
after the first "for" there is a new i=2, which
seems to staty at 2 all the time; the following
while does not change this value Why should it? You don't tell it to.
( the beginning for
i++ does not change this)It does. It just gets re-set to 2 after the for loop-
and so seems to print 2 at
all times (??)Yeah. What else?
then the inner loop seems to count up all the
doubbles of the new prime number and thrwoes it out
as false at the end of it; That part is definitely unreadable.

Simple Java regex question

I have a file with set of Name:Value pairs
e.g
Action1:fail
Action2:pass
Action3:fred
Using regex package I Want to get value of Name "Action1"
I have tried diff things but I cannot figure out how I can do it. I can find Action1: is present or not but dont know how I can get value associated with it.
I have tried:
Pattern pattern = Pattern.compile("Action1");
CharSequence charSequence = CharSequenceFromFile(fileName); // method retuning charsq from a file
Matcher matcher = pattern.matcher(charSequence);
if(matcher.find()){
int start = matcher.end(0);
System.out.println("matcher.group(0)"+ matcher.group(0));
how I can get value associated with specific tag?
thanks
anmol

read the data from the text file on a line basis and you can do:
String line //get this somehow
String[] keyPair = line.split(":")g
System.out.println(keyPair[0]); //your name
System.out.println(keyPair[1]); //your valueor if you've got the text file in one big string:
String pattern = "(\\a*):(\\a*)$"; //{alpha}:{alpha}newline //?
//then
//do some things with match objects
//look in the API at java.util.regex

Problem with getNodeValue() - simple Java XPath question

I am trying to extract the node values from a XML file:
<root>
<frame>
     <boxes>
       <box>
          <spec>22</spec>
          <spec>2222</spec>
       </box>
       <box>
          <spec id="BA" value="short"/>
          <spec id="BB" value="thin"/>
          <spec id="BC" value="black"/>
          <spec id="BD" value="full"/>
          <spec id="BE" value="7"/>
          <spec id="BF" value="deactive"/>
       </box>
     </boxes>
     <circles>
       <circle id="CA" value="blue"/>
       <circle id="CB" value="green"/>
     </circles>
</frame>
</root>I use this code:
         XPathFactory factory = XPathFactory.newInstance();
         XPath xpath = factory.newXPath();
         XPathExpression xPathExpression = xpath.compile("/root/frame/boxes/box/spec");
         Object result = xPathExpression.evaluate(doc, XPathConstants.NODESET);
         NodeList nodes = (NodeList) result;
         for (int i = 0; i < nodes.getLength(); i++) {
             System.out.println(nodes.item(i).getNodeValue());
         }But only:
null
null
null
null
null
null
null
null
get printed. I would have assumed:
22
2222
null
null
null
null
null
null
since the two first spec nodes contains the above numbers. Any ideas?

change this:
XPathExpression xPathExpression = xpath.compile("/root/frame/boxes/box/spec");to this:
XPathExpression xPathExpression = xpath.compile("/root/frame/boxes/box/spec/text()");Need to xpath all the way down to the text of the node.
You could use
System.out.println(nodes.item(i).getTextContent());with your current xpath but if the spec node has children, these will also be included in the output.

Efficiency Question: Simple Java DC vs Used WD Component

Hello guys,
The scenario is - I want to call a function that returns a FileInputStream object so I can process it on my WD view. I can think of two approaches - one is to simply write a simple Java DC that does so and just use it as a used DC so I can call the functionality from there. Or create another WD DC that exposes the value (as binary) via component interface.
I'm leaning on the simple Java DC approach - its easier to create. But I'm just curious on what would be the Pro-side (if there's any) if I use the WD Component interface approach? Is there a plus for the efficiency? (Though I doubt) Or is it just a 'best/recommended practice' approach?
Thanks!
Regards,
Jan

Hi Jan
>one is to simply write a simple Java DC that does so and just use it as a used DC so I can call the functionality from there
Implemented Java API for the purpose mentioned in your question is the right way, I think. The Java API can be even located in the same WebDynpro DC as your WebDynpro components. There is not strongly necessity to put it into separate Java DC.
>Or create another WD DC that exposes the value (as binary) via component interface
You should not do this because in general WD components' purpose is UI, not API. Implementing WD component without any UI, but with some component interface has very-very restricted use cases. Such WD component shall only be a choice in the cases when the API is WebDynpro based and if you have to strongly use WebDynpro Runtime API in order to implement your own API.
If your API does not require WebDynpro Runtime API invocations or anything else related to WebDynpro then your choice is simple Java API.
>But I'm just curious on what would be the Pro-side (if there's any) if I use the WD Component interface approach? Is there a plus for the efficiency?
No. Performance will be better in simple Java API then in WebDynpro component interface. The reason is the API will not pass thought heavy WebDynpro engine.
BR, Siarhei

Java Novice Question (don't shoot me)

Hello,
I wanted to ask a very novice question, that I can't seem to find an answer to.
I have Eclipse IDE for Java, and I also have Visual Studio (C#). In Visual Studio, you can create a application project, drag and drop a button, then double click the button tod be taken to the code behind the button, that's where you insert your code on what you want the button to do once you click it.
Is there something similiar to that in Java (I know there must be), where you can drag and drop textboxes, buttons, etc., and then double click those items to code?
Any light that ANYONE can shed on this would be highly appreciated!
Thanks!
Waleed

waldo33 wrote:
Okay, thank you for the patience! I will download the "kitchen sink" version, and by that I assume you mean the biggest Netbeans file :)Yeap.
Regarding "building a website"...by that I mean...I want to build a simple website, which incorporates (MySQL which I already installed, installed the ConnectorJ, etc.), a front end (JSP would be nice, which i'm learning), and ofcourse the backend Java coding.Right. Thats not what I got from your first message. I thought your were simply after create a rich client (I.e. Java Swing). Creating a web site is a more advanced topic. I don't know of any GUI editors for it, but then I don't do it (I half expect someone to post IntelliJ IDEA now). But we are just talking HTML and lots of HTML editors exist.
I don't care how easy the website, as long as I can learn (on a basic level). You are going to have to look up tutorials on Java EE.Personally I don't think this is a "new to java" topic.
(Scary, covers all of JEE) [The Java EE 5 Tutorial|http://java.sun.com/javaee/5/docs/tutorial/doc/]
Re: "Right tool for right job"...are you suggesting that I have Eclipse for coding Java, and NetBeans for more GUI apps and developement?The UI for rich clients I do in NetBeans. Everything else I do in Eclipse. But this is just me, and I'm luck enough to be able to dictate tool chains.

Java coding in combo box

how to call the set of java coding by using combo box................

Siva,
Try avoiding opening different threads for the same questions...
Combox Box date format
You can use the option Edit/Reply to update your thread..
-Anil

Can we call a simple java application from ESB

Please let me know how this can be done by using a ESB. The application jar exists on the host server. How we can pass parameters etc and receive results from this application.
Any help will be greatly appreciated.
Prakash

Not sure if I completely understand your question, but you can certainly try following ways:
- call your java application via WSIF. ESB with JAVA wsif is available in 10.1.3.3.1 only (it is not supported in 10.1.3.3 very well).
- you will have to include this jar file in server.xml or bpel/system/classes so that it is available to the SOA jvm.
- You mentioned it is simple java application, but if your java API has complex (object) input and output, you will need some work
HTH,
Chintan

Re: Using simple java class in an .war file.

Hi All,
I have a simple question,
Can I access an simple java class from a jsp file that I have written by putting it in the "classes" folder?? What entry should go in the web.xml file?
Here is my directory structure:
sample.war
|
----test.jsp <file>
|
----WEB-INF <folder>
| |
| ----classes<folder>
| | |
| | ----simpleJavaClass.class<file>
| |
| ----lib<folder>
| |
| ----web.xml
I want to access the simpleJavaClass.class from the jsp test.jsp.
Please suggest.
Thanks and regards
Ayusman

It is possible to access the class in u r classes folder from u r jsp file.
For example
<%@ page import="com.test.service.PricingSolution,
com.test.core.PhoneNumber
%>
<% PricingSolution solution = (PricingSolution)session.getAttribute("solution"); %>
This is a simple scriplet example. You do the same using jstl tags also.
--Shinoy

Simple Java Coding Question

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