Does calling class methods from bean and JSP cause collision?

Hi,
Please look at the class below:
public class X
// no member variable
public X() {}
// pay attention to static keyword
public static int getY()
Think a bean (say BeanZ) that make calls to getY() method without initializing the class X (like this: X.getY() )
And think many users having "page scope" in JSP make call to BeanZ or directly calls it from JSP.
I'm wondering if any collision occurs because of STATIC method? Should I use "SYNCHRONIZED" keyword with it? If so, what about Math.cos() which also is a non synchronized static method ? Shouldn't I use Math.cos() (and the other static methods) in JSP or bean?
Thank you for your help.
Ali Sadik

Hi,
Thank you for your quick answer. Think my class like this:
public class X
// no member variable
public X() {}
// pay attention to static keyword
public static int[] getY(int a, int[] b)
// i know there is no need for the extra array.
// just for example ;)
int[] ret = new int[b.length];
for(int i = 0; i < b.length; i++)
ret[i] = a * b;
return ret;
Does it the type of class that you've mentioned ? It makes calculation to produce dynamic result. Shouldn't I use it as static ? If your answer is yes, what about Math.cos()? Doesn't it have dynamic calculation?
Thanks a lot.

Similar Messages

Calling class methods from jsp

hi - this seems like it should be painfully obvious but I am missing something somewhere and can't seem to get it to work.
The end result I am looking for is to be able to call a method similar to how I would do it in PHP or ASP.
To do this I have writte the following class (just as an example) and combpiled it to /WEB-INF/classes/com/example/util/Echo.class:
package com.example.util;
class Echo
public static void main(String[] args)
System.out.println(args[0]);
I then have a sample JSP that I attempt to use this in that looks like:
<%@ page import="com.example.util.Echo" %>
<%
RDmail("I'm using my Echo class.");
%>
My expectation would be that when I run this page in a browser, I see the text "I'm using my Echo class." printed out on the page. Instead I get the following error:
An error occurred at line: 1 in the jsp file: /classtest.jsp
Generated servlet error:
[javac] Compiling 1 source file
/var/tomcat4/work/Standalone/localhost/raindance/classtest_jsp.java:47: cannot resolve symbol
symbol : method Echo (java.lang.String)
location: class org.apache.jsp.classtest_jsp
Echo("I'm using my Echo class");
^
1 error
What am I doing wrong?

Umm... I'm not entirely sure what you're attempting to do, but it looks like there's some discrepancy between your error message and your code...
RDmail("I'm using my Echo class."); in your code
and
Echo("I'm using my Echo class"); in your error message.
Is this just a cut/paste error?
Also, the main() method is only called from a command line, and will not be run when you instantiate your bean in a JSP. If you want to have your String printed out when you create a new object, you should put the print statement in the constructor. Which would then be called when you created a new object..
Echo e = new Echo("I'm using my Echo class");
Or, you could create a static method inside Echo.java that prints out the statement.
Finally, your System.out most likely will not print to your browser, but probably to a standard log, or perhaps a command window.

Problem calling Java method from JavaScript in JSP / ADF

Hi all,
In my JavaScript onMouseUp() function, I need to call a method on my Java backing bean. How is this done? Info on the web indicates a static Java method can be called by simply "package.class.staticMethod(...)". but when I put the statement
"jsf.backing.GlobalRetriever.createBasemap(affectedLayer);"
I get an error message "jsf is undefined".
The functionality I'm trying to get is: I have a custom slider control and based on its value, I want to call oracle map viewer specifying a map extent of the (current extent / slider value) to do a zoom in/out. In addition, the slider uses a onMouseMove() function to change the size of the image display so it looks like a dynamic zoom in/out.
Please assist or let me know if I can provide some additional information. Thanks in advance.
Jim Greetham

No. The Java and Javascript in a Faces application are really working in two different universes.
Java is running on the server. It generates HTML (and sometimes even Javascript) and sends that to the client machine. That's where all your backing beans are.
Javascript runs directly in the browser. There's no way anything on the server can have access to anything you define in Javascript, unless you explicitly send that information back to the server, either via standard form submission (which only works when someone presses a "Submit" button) or via an Ajax-type call. So otherwise, nothing you define in Javascript will ever be available to a backing bean.

Calling class methods from listSelectionListener

Hi,
I have a GUI class which containt a few Jlist. I also have two listSelectionListener classes. How do I reach methods in the GUI class from the listSelection classes. Can I pass a reference of GUI to them somehow?
Karl XII

For the benefit of future readers, the answer is yes, either in your listSelectionListener constructor, or a listSelectionListener method you implement. In either case, just set a listSelectionListener member variable (added by you) to the desired value.

EJB 3.1 @Asynchronous and calling other methods from within

Hey all,
I am helping a friend set up a test framework, and I've turned him on to using JEE6 for the task. I am decently familiar with entity beans, session beans, and such. One of the new features is @Asynchronous, allowing a method to be ran on a separate thread. The test framework generally needs to spawn potentially 1000's of threads to simulate multiple users at once. Originally I was doing this using the Executor classes, but I've since learned that for some reason, spawning your own threads within a JEE container is "not allowed" or bad to do. I honestly don't quite know why this is.. from what I've read the main concern is that the container maintains threads and your own threads could mess up the container somehow. I can only guess that this might be possible if your threads use the container services in some way.. but if anyone could enlighten me on the details as to why this is bad, that would be great.
None the less, EJB 3.1 adds the async capability and I am now looking to use this. From my servlet I use @EJB to access the session bean, and call an async method. My servlet returns right away as it should. From the async method I do some work and using an entity bean store results, so I don't need to return a Future object. In fact, my ejb then makes an HttpClient call to another servlet to notify it that the result is ready.
My main question though, is if it's ok to call other methods from the async method that are not declared @Asynchronous. I presume it is ok, as the @Asynchronous just enables the container to spawn a thread to execute that method in. But I can't dig up any limitations on the code within an async method.. whether or not it has restrictions on the container services, is there anything wrong with using HttpClient to make a request from the method.. and making calls to helper methods within the bean that are not async.
Thanks.

851827 wrote:
Hey all,.. from what I've read the main concern is that the container maintains threads and your own threads could mess up the container somehow. I can only guess that this might be possible if your threads use the container services in some way.. but if anyone could enlighten me on the details as to why this is bad, that would be great.
Yes since the EE spec delegated thread management to conatiners, the container might assume that some info is available in the thread context that you may not have made available to your threads.
Also threading is a technical implementation detail and the drive with the EE spec is that you should concentrate on business requirements and let the container do the plumbing part.
If you were managing your own threads spawned from EJBs, you'd have to be managing your EJBs' lifecycle as well. This would just add to more plumbing code by the developer and typically requires writting platform specific routines which the containers already do anyway.
>
None the less, EJB 3.1 adds the async capability and I am now looking to use this. From my servlet I use @EJB to access the session bean, and call an async method. My servlet returns right away as it should. From the async method I do some work and using an entity bean store results, so I don't need to return a Future object. In fact, my ejb then makes an HttpClient call to another servlet to notify it that the result is ready.
My main question though, is if it's ok to call other methods from the async method that are not declared @Asynchronous. I presume it is ok, as the @Asynchronous just enables the container to spawn a thread to execute that method in. But I can't dig up any limitations on the code within an async method.. whether or not it has restrictions on the container services, is there anything wrong with using HttpClient to make a request from the method.. and making calls to helper methods within the bean that are not async.
Thanks.If you want to be asynchronous without caring about a return value then just use MDBs.
The async methods have no restrictions on container services and there is nothing wrong with calling other non async methods. Once the async method is reached those annotations don't matter anyway (unless if you call thhose methods from a new reference of the EJB that you look up) as they only make sense in a client context.
Why do you need to make the call to the servlet from the EJB? Makes it difficult to know who is the client here. Better use the Future objects and let the initial caller delegate to the other client components as needed.

Accessing view object class (impl) method from bean (or vice versa)

Halo everyone, I am using JDeveloper 11.1.2.1.0
I have a UsersViewImpl class with a method which refresh the user table like below.
public void resetEmployeeSearch() {
removeApplyViewCriteriaName("viewCriteria");
executeQuery();
and I have a UserBean class with a method which reset the search fields values like below.
public void resetInput(ActionEvent actionEvent) {
........RichInputText = input ...
input.setValue("");
AdfFacesContext.getCurrentInstance().addPartialTarget(searchForm);
I would like to implement it in such a way that, once I press a button, both methods will be called.
I have tried to call from bean method using UsersViewImpl vs = new UsersViewImpl ..... which is wrong and wont work.
I have read about doing something like ViewObject vo = am.findViewObject("DeptView1") but I duno how to use it because I cant have a proper example.
Any suggestion on accessing view object class (impl) method from bean (or vice versa)?
Or is there any way to combine both method in the same class ?
Thank you :(

User, if you get class not found exceptions you need to tell us which classes you can't find. The JSFUtils and ADFUtils classes needing some other libraries which should already be part of your Fusion Web Application template (which your adf application should be based on). If you did not use this application template, you may have to add some libraries yourself.
What is the diff of using the ADFUtils and OperationBinding way?
The ADFUtils can get you access to the application module which you then use to call exposed methods on. The disadvantage of doing this is that you have to implement your own exception framework which then handles exceptions thrown by the application module. An other thing is that if you e.g. alter a VO which you use on the page this changes are not seen on the page until you refresh the page. The binding layer does not know about these changes so the iterators (which are used on the page to show the data) are not refreshed and so you don't see the changes.
In general you should avoid using the application modul in a managed bean method and always use the binding layer (OperationBinding) to call methods. This ensures that exceptions are all handled the same way and that changes to the data model are reflected in the GUI.
Timo

Operation not found error while calling AM methods from managed bean

Hi,
operation not found error while calling AM methods from managed bean.
written a method with two parameters in AM.
exposed the method in AM client interface
in the page bindings added the method in method action ..left empty in the value fields of the parameters.
calling the method from managed bean like below
String userNameVal = (String)userName.getValue();
String passwordVal = (String)password.getValue();
OperationBinding operationBinding =
ADFUtils.findOperation("verifyLogin");
operationBinding.getParamsMap().put("userName",userNameVal);
operationBinding.getParamsMap().put("password",passwordVal);
operationBinding.execute();
i am getting operation verifyLogin not found error.Please suggest me something to do.
Thanks
Satya

Hi vlsn,
Can you try with the below code
// in your backing bean
OperationBinding operation = bindings.getOperationBinding("verifyLogin");
//Put your both parameters here
operation.getParamsMap().put("parameter_name1", parameterValue1);
operation.getParamsMap().put("parameter_name2", parameterValue2);
operation.execute();
if (operation.getResult() != null) {
Boolean result = (Boolean) operation.getResult();
and share the result.
regards,
Rajan

Calling a method from a super class

Hello, I'm trying to write a program that will call a method from a super class. This program is the test program, so should i include extends in the class declaration? Also, what code is needed for the call? Just to make things clear the program includes three different types of object classes and one abstract superclass and the test program which is what im having problems with. I try to use the test program to calculate somthing for each of them using the abstract method in the superclass, but its overridden for each of the three object classes. Now to call this function what syntax should I include? the function returns a double. Thanks.

Well, this sort of depends on how the methods are overridden.
public class SuperFoo {
public void foo() {
     //do something;
public void bar(){
     //do something
public class SubFoo extends SuperFoo {
   public void foo() {
      //do something different that overrides foo()
   public void baz() {
      bar(); //calls superclass method
      foo(); //calls method in this (sub) class
      super.foo(); //calls method in superclass
}However, if you have a superclass with an abstract method, then all the subclasses implement that same method with a relevant implementation. Since the parent method is abstract, you can't make a call to it (it contains no implementation, right?).

Need help calling a method from an immutable class

I'm having difficulties in calling a method from my class called Cabin to my main. Here's the code in my main              if(this is where i want my method hasKitchen() from my Cabin class)
                    System.out.println("There is a kitchen.");
               else
                    System.out.println("There is not a kitchen.");
               }and here's my method from my Cabin class:public boolean hasKitchen()
     return kitchen;
}

You should first have an instance of Cabin created by using
   Cabin c = ....
   if (c.hasKitchen()) {
     System.out.println("There is a kitchen.");
   } else {
        System.out.println("There is not a kitchen.");
   }

Calling a method from another class or accessing a component from another

Hi all
im trying to make a find/replace dialog box
my main application form has a jtextpane and when i open up the find and replace dialog box it has two textboxes (find and replace)
now i have the code to do the finding on my jtextpane but how do i call that code to do the find method?
I have tried having the code in my main application class but then how do i call that method from my dialog box class?
ive also tried having the code in my dialog box class, but then how to i tell it to work on my jtextpane which is in my main ap class?

well if someone had been nice enough to provide me
with a tutorial i wouldnt have gotten into this
muddle, no need to be rude is there!I'm not rude. And you also wouldn't have gotten into the muddle if you searched yourself. This site provides many very good tutorials about all kinds of stuff.
http://java.sun.com/docs/books/tutorial/java/javaOO/classes.htmlAmong other things, it mentions that "static" defines everything that belongs to a class, as opposed to an object.

Call C# method from javascript in WebView and retrieve the return value

The issue I am facing is the following :
I want to call a C# method from the javascript in my WebView and get the result of this call in my javascript.
In an WPF Desktop application, it would not be an issue because a WebBrowser
(the equivalent of a webView) has a property ObjectForScripting to which we can assign a C# object containg the methods we want to call from the javascript.
In an Windows Store Application, it is slightly different because the WebView
only contains an event ScriptNotify to which we can subscribe like in the example below :
void MainPage_Loaded(object sender, RoutedEventArgs e)
this.webView.ScriptNotify += webView_ScriptNotify;
When the event ScriptNotify is raised by calling window.external.notify(parameter), the method webView_ScriptNotify is called with the parameter sent by the javascript :
function CallCSharp() {
var returnValue;
window.external.notify(parameter);
return returnValue;
private async void webView_ScriptNotify(object sender, NotifyEventArgs e)
var parameter = e.Value;
var result = DoSomerthing(parameter);
The issue is that the javascript only raise the event and doesn't wait for a return value or even for the end of the execution of webView_ScriptNotify().
A solution to this issue would be call a javascript function from the webView_ScriptNotify() to store the return value in a variable in the javascript and retrieve it after.
private async void webView_ScriptNotify(object sender, NotifyEventArgs e)
var parameter = e.Value;
var result = ReturnResult();
await this.webView.InvokeScriptAsync("CSharpCallResult", new string[] { result });
var result;
function CallCSharp() {
window.external.notify(parameter);
return result;
function CSharpCallResult(parameter){
result = parameter;
However this does not work correctly because the call to the CSharpResult function from the C# happens after the javascript has finished to execute the CallCSharp function. Indeed the
window.external.notify does not wait for the C# to finish to execute.
Do you have any solution to solve this issue ? It is quite strange that in a Window Store App it is not possible to get the return value of a call to a C# method from the javascript whereas it is not an issue in a WPF application.

I am not very familiar with the completion pattern and I could not find many things about it on Google, what is the principle? Unfortunately your solution of splitting my JS function does not work in my case. In my example my CallCSharp
function is called by another function which provides the parameter and needs the return value to directly use it. This function which called
CallCSharp will always execute before an InvokeScriptAsync call a second function. Furthermore, the content of my WebView is used in a cross platforms context so actually my
CallCSharp function more look like the code below.
function CallCSharp() {
if (isAndroid()) {
//mechanism to call C# method from js in Android
//return the result of call to C# method
} else if (isWindowsStoreApp()) {
window.external.notify(parameter);
// should return the result of call to C# method
} else {
In android, the mechanism in the webView allows to return the value of the call to a C# method, in a WPF application also. But I can't figure why for a Windows Store App we don't have this possibility.

How to call a method from class interface

Hi ,
I want to call a method from a 'class interface' in a BADI .
Class Interface -- /SAPSRM/CL_PDO_DO_BASE
Method -- /SAPSRM/IF_PDO_DO_PARTNER_BASE~UPDATE_ITEM_PARTNERS
Please let me know how can I call this method in my BADI.
Thanks-

Hi Harmeet,
Follow these simple steps.
1. Create an instance of class interface /SAPSRM/CL_PDO_DO_BASE if method /SAPSRM/IF_PDO_DO_PARTNER_BASE~UPDATE_ITEM_PARTNERS is instance method and
call instance -> /SAPSRM/IF_PDO_DO_PARTNER_BASE~UPDATE_ITEM_PARTNERS
2.if method /SAPSRM/IF_PDO_DO_PARTNER_BASEUPDATE_ITEM_PARTNERS is static method ,call directly using class interface like /SAPSRM/CL_PDO_DO_BASE=> /SAPSRM/IF_PDO_DO_PARTNER_BASEUPDATE_ITEM_PARTNERS.
If you feel any dificulty in declaring instances and call methods,
Goto EDIT-> Pattern ->ABAP Object Patterns, Give class name , instance name and method, you got the required code.
Thanks,
Prasad.

How to call a method from another class

I have a problem were i have to call a method from another class. What is the command line that i have to use. Thanks.

Here's one I wipped up in 10 minutes... Cool!
package forums;
import javax.swing.JFrame;
import javax.swing.JTextArea;
import krc.utilz.io.Filez;
import java.io.FileNotFoundException;
class FileDisplayer extends JFrame
private static final long serialVersionUID = 0L;
FileDisplayer(String filename) {
    super(filename);
    this.setDefaultCloseOperation(EXIT_ON_CLOSE);
    this.setSize(600, 800);
    JTextArea text = new JTextArea();
    try {
      text.setText(Filez.read(filename));
    } catch (FileNotFoundException e) {
      text.setText(e.toString());
    this.add(text);
public static void main(String args[]) {
    final String filename = (args.length>0 ? args[0] : "C:/Java/home/src/forums/FileDisplayer.java");
    try {
      java.awt.EventQueue.invokeLater(
        new Runnable() {
          public void run() {
            new FileDisplayer(filename).setVisible(true);
    } catch (Exception e) {
      e.printStackTrace();
Filez.read
   * reads the given file into one big string
   * @param String filename - the name of the file to read
   * @return the contents filename
public static String read(String filename) throws FileNotFoundException {
    return Filez.read(new FileReader(filename));
   * Reads the contents of the given reader into one big string, and closes the reader.
   * @param java.io.Reader reader - a subclass of Reader to read from.
   * @return the whole contents of the given reader.
public static String read(Reader in) {
    try {
      StringBuffer out = new StringBuffer();
      try {
        char[] bfr = new char[BFRSIZE];
        int n = 0;
        while( (n=in.read(bfr,0,BFRSIZE)) > 0 ) {
          out.append(bfr,0,n);
      } finally {
        if(in!=null)in.close();
      return out.toString();
    } catch (IOException e) {
      throw new RuntimeIOException(e.getMessage(), e);
}Edited by: corlettk on Dec 16, 2007 1:01 PM - dang [code [/tags][

Call jpf method from jsp

Is there anyway to call a method in Controller.jpf from a jsp page? I want to have my jsp page call a method from the jpf controller through an onChange event in the select tag. Otherwise I will have to write a large amount of javascript directly into my jsp page and really defeats the purpose of the MVC architecture. Any help is greatly appreciated. Thanks in advance.

The jsp might look something like this:
<netui:form action="DoThisOnChange">

<netui:select dataSource"" optionsDataSource="" onChange="this.form.submit()"/>
</netui:form>
And in JPF declare action named "DoThisOnChange" and write the logic to be done on event "onChange".
--SJ

Calling a method from another class... that requires variables?

I'm calling a method from another class to change the date (its a date object) in another class.
I keep getting the error 'setDate(int,int,int) in Date cannot be applied to ()'
My code is:
public int changeDate()
cycleDate.setDate();
}I'm guessing I need to pass 3 parameters (day, month, year), but I'm not sure how! I have tried, but then I get errors such as ')' expected?
Any ideas! :D

f1d wrote:
I'm calling a method from another class to change the date (its a date object) in another class.
I keep getting the error 'setDate(int,int,int) in Date cannot be applied to ()'
My code is:
public int changeDate()
cycleDate.setDate();
}I'm guessing I need to pass 3 parameters (day, month, year), seems that way from the error you posted
but I'm not sure how!
setDate(16, 6, 2008);
I have tried, but then I get errors such as ')' expected?
Any ideas! :Dyou need to post your code if you're getting specific errors like that.
but typically ')' expected means just that, you have too many or not enough parenthesis (or in the wrong place, etc.)
i.e. syntax error

Does calling class methods from bean and JSP cause collision?

Similar Messages

Maybe you are looking for