Creating class objects

Does anyone know why someone would use Example1 instead of Example2 in a JSP. In both cases you should have access to the methods in the class created as somename from the JSP but is one better than the other or why I should do one instead of the other.
Example1:
<jsp:useBean id="somename" scope="request" class="someclass" />
<%
somename.someclass(arguments);
%>
Example2:
<%@ page language="java" import="someclass" %>
<%
someclass somename = new someclass(arguments);
%>

JSP tags are a way of avoiding the use of Scriptlets in your JSP code. JSP's, like many server side page generation suffers from the mixing of presentation and "business" or control logic. You end up with a nasty mess of Java embedded in HTML tags.
The tags are XML so they match the format of HTML tags a lot closer than Java scriptlets ever will.
Another advantage of using tags, especially with things like useBean is that you can add tags to set properties of a bean that are received via a request. To set all properties of a bean..
<jsp:setProperty name="somename" property="*" />
which is a lot shorter than
<%
MyBean somename = new MyBean();
request.setAttribute("somename", somename);
String param1 = request.getParameter("param1");
if(param1 != null) {
int p1 = Integer.parseInt(param1);
somename.setP1(p1);
} // Repeat for each possible parameter
%>
If you have lots of data being passed say from a form, this is a lot of messy code that is replaced by 1 single additional XML tag. If you build in propertyChange support etc into your bean then you will also have the chance to proof property values as they are fed to the bean.
Don't forget, you are most likely going to have to pass this JSP and others like it to an HTML designer who won't be familiar with Java at all. The learning curve for the tags is nowhere near as steep as learning Java itself.

Similar Messages

Create Class objects from an Array of File Objects

Hi There,
I'm having extreme difficulty in trying to convert an array of file objects to Class objects. My problem is as follows: I'm using Jfilechooser to select a directory and get an array of files of which are all .class files. I want to create Class objects from these .class files. Therefore, i can extract all the constructor, method and field information. I eventually want this class information to display in a JTree. Very similar to the explorer used in Netbeans. I've already created some code below, but it seems to be throwing a NoSuchMethodError exception. Can anyone please help??
Thanks in advance,
Vikash
/* the following is the class im using */
class FileClassLoader extends ClassLoader {
private File file;
public FileClassLoader (File ff) {
this.file = ff;
protected synchronized Class loadClass() throws ClassNotFoundException {
Class c = null;
try {
// Get size of class file
int size = (int)file.length();
// Reserve space to read
byte buff[] = new byte[size];
// Get stream to read from
FileInputStream fis = new FileInputStream(file);
DataInputStream dis = new DataInputStream (fis);
// Read in data
dis.readFully (buff);
// close stream
dis.close();
// get class name and remove ".class"
String classname = null;
String filename = file.getName();
int i = filename.lastIndexOf('.');
if(i>0 && i<filename.length()-1) {
classname = filename.substring(0,i);
// create class object from bytes
c = defineClass (classname, buff, 0, buff.length);
resolveClass (c);
} catch (java.io.IOException e) {
e.printStackTrace();
return c;
} // end of method loadClass
} // end of class FileClassLoader
/* The above class is used in the following button action in my gui */
/* At the moment im trying to output the data to standard output */
private void SelectPackage_but2ActionPerformed(java.awt.event.ActionEvent evt) {
final JFileChooser f = new JFileChooser();
f.setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY);
int rVal = f.showOpenDialog(Remedy.this);
// selects directory
File dir = f.getSelectedFile();
// gets a list of files within the directory
File[] allfiles = dir.listFiles();
// for loop to filter out all the .class files
for (int k=0; k < allfiles.length; k++) {
if (allfiles[k].getName().endsWith(".class")) {
try {
System.out.println("File name: " + allfiles[k].getName()); // used for debugging
FileClassLoader loader = new FileClassLoader(allfiles[k]);
Class cl = loader.loadClass();
//Class cl = null;
Class[] interfaces = cl.getInterfaces();
java.lang.reflect.Method[] methods = cl.getDeclaredMethods();
java.lang.reflect.Field[] fields = cl.getDeclaredFields();
System.out.println("Class Name: " + cl.getName());
//print out methods
for (int m=0; m < methods.length; m++) {
System.out.println("Method: " + methods[m].getName());
// print out fields
for (int fld=0; fld < fields.length; fld++) {
System.out.println("Field: " + fields[fld].getName());
} catch (Exception e) {
e.printStackTrace();
} // end of if loop
} // end of for loop
packageName2.setText(dir.getPath());
}

It's throwing the exeption on the line:
FileClassLoader loader = new FileClassLoader(allfiles[k]);
I'm sure its something to do with the extended class i've created. but i cant seem to figure it out..
Thanks if you can figure it out

Class object from XML.

Hi.
I want to create DataGrid with itemReneder for each column.
This is inline generated itemRenderer:
DataGridColumn.itemRenderer = new
ClassFactory(MyCustomClass);
// MyCustomClass - it manually generated class which contains
some form items(TextInput, Combox..e.t.c.)
I want to consturct ItemRenderer dynamicly. For this i need
to create Class object and send it to itemRenderer:
var component:DynamicFormClass = new DynamicFormClass();
var newComponent:Class =
component.someMethodWhichWillCreateForm(configData); // - this will
return Class which will generate form items that described in
configData
DatagridColumn.itemRenderer = new ClassFactory(newComponent);
This code is how i see solvetion of this problem, but this
doesnt work.
I really don't know how it to create and will be very
thankful for any dicision and answers how to make it.
Thank you.

"Dmitry Sergeev" <[email protected]> wrote
in message
news:g8eghj$881$[email protected]..
> Hi.
> I want to create DataGrid with itemReneder for each
column.
>
> This is inline generated itemRenderer:
> DataGridColumn.itemRenderer = new
ClassFactory(MyCustomClass);
> // MyCustomClass - it manually generated class which
contains some form
> items(TextInput, Combox..e.t.c.)
>
> I want to consturct ItemRenderer dynamicly. For this i
need to create
> Class
> object and send it to itemRenderer:
> var component:DynamicFormClass = new DynamicFormClass();
> var newComponent:Class =
> component.someMethodWhichWillCreateForm(configData);
> // - this will return Class which will generate form
items that described
> in
> configData
> DatagridColumn.itemRenderer = new
ClassFactory(newComponent);
Use getDefinitionByName and ClassFactory to dynamically
create your class.
Just be sure that you actually have at least one "hard"
reference to each
class you intend to use, or the class might not get compiled
into your swf.
Here's a full write-up of how to do that:
http://www.paulofierro.com/archives/520/
HTH;
Amy

Multidimensional array in jquery class/object

I'm trying to get into javascript and jquery for a hobby project of mine. Now I've used the last 4 hours trying to find a guide on how to create class objects that can contain the following information
Identification : id
Group : group
Persons : array(firstname : name, lastname : name)
Anyone know of a tutorial that can show me how to do this?
I found this page where I can see that an object can contain an array, but it doesn't state whether it is possible to use a multidimensional array.
And this page just describes the object with normal values.
Any pointers in the right direction are appreciated.

There are no classes in JavaScript. It uses a different style of objects and what you found is indeed what you need.
Well, it might help to think about it as a dynamic, runtime-modifiable object system. An Object is not described by class, but by instructions for its creation.
Here you have your object. Note that you can use variables everywhere.
var id = 123;
var test = {"Identification": id,
"Group": "users",
"Persons": [{"firstname":"john", "lastname":"doe"},{"firstname":"jane","lastname":"doe"}]
This is identical to the following code. (The first one is a lot nicer, though.)
var id = 123;
var test = new Object();
test.Identification = id;
test["Group"] = "users;
test.Persons = new Array();
test.Persons.push({"lastname":"doe","lastname":"john"});
test.Persons.push({"lastname":"doe","lastname":"jane"});
As you can see, you can dynamically add new properties to an object. You can use both the dot-syntax (object.property) and the hash syntax (object["property"]) in JavaScript.

About Class Object as Array

Hello.. I'm beginner in Java Programming
Now i learn about Array.. i'm not understand about use class object become array. for example i'm create class object Card.
Then i call Card object to CardTest as main object and Card object called as array.
can you tell me about how to work Card object as array in CardTest ?
Edited by: 994075 on Mar 14, 2013 11:55 PM

994075 wrote:
yup..thanks guru :DI'm no guru, I just bought a decent Java book 10 years ago and here I am.
so i guess Object Class can be array :).I don't get that statement. You can store objects in an array, if that's what you mean. An array itself is also an object.
but i'm not understrand if static method in Card object can be called automatically when Card initialized in CardTest?a) research constructors
b) you usually don't need static methods, its just something that people new to the language tend to overuse because then you don't have to create object instances. Forget about static methods, try to make it work using regular non-static methods.
And you really should read and study more, you're coming to the forum way too soon. First get a solid knowledge base, the only thing you're doing now is asking questions that you could have answered for yourself by studying more.

How to create multiple objects within a class

I have a item.lvclass which has an item.ctl (contains a cluster of class private data). I need to add another object (item2.ctl) within that same class so that I can reuse the code for that class.
So how do you create additional objects within the same class?

Well... right now... I've cornered myself going down this path: http://forums.ni.com/t5/LabVIEW-Idea-Exchange/LVOOP-Interfaces/idc-p/1314637#M8918
Seems like the solution in the idea was not implemented yet....
Okay. I will try to describe the situation differently...
Let's say I have a Car.lvclass
I want to have two objects: sedan & roadster
both have similar properties, but also have different properties:
4 doors vs 2 doors
hardtop vs convertible
silver vs white (color)
I want the two objects to be of the same class so that they can share the same private and public VI's. As a matter of fact, I want to have both objects in the VI's within the Car.lvclass.

What is the advantage of using IB to create XIBs/Class Objects over coding?

Hi all,
I hoping someone can provide me some pros and cons as to when I should use IB to create XIBs and/or class objects as opposed to directly coding them.
For example, if I choose Apple's Template for creating a Navigation Based Application (cocoa touch), the project creates two NIB files - MainMenu and RootViewController.
However looking at one of demo apps SimpleDrillDown, it does not have a RootViewController XIB and instead creates it via code.
Another example from the same two apps is that the template generates a "Navigation Controller" class object in the Mainmenu.xib. SimpleDrillDown does not bother with this in the XIB, but uses code to generate the controller:
- (void)applicationDidFinishLaunching:(UIApplication *)application {
// Create the navigation and view controllers
RootViewController *rootViewController = [[RootViewController alloc] init];
UINavigationController *aNavigationController = [[UINavigationController alloc] initWithRootViewController:rootViewController];
self.navigationController = aNavigationController;
[aNavigationController release];
[rootViewController release];
// Configure and show the window
[window addSubview:[navigationController view]];
[window makeKeyAndVisible];
as opposed to the template which only needs this:
- (void)applicationDidFinishLaunching:(UIApplication *)application {
// Configure and show the window
// Navigation Controller is defined in MainWindow.xib
[window addSubview:[navigationController view]];
[window makeKeyAndVisible];
So what are the advantages of each approach. Why does apple suggest one approach and yet all its demos use another.
Any thoughts, answers gratefully received.
TIA, Michael.

You can do whatever you're comfortable with, but most of the best Cocoa programmers--the ones on the Mac, I mean--recommend putting everything you can into Interface Builder.
It's a little like the difference between writing a program to do a bunch of financial calculations and using a spreadsheet. Yeah, the program can do everything the spreadsheet can--and more besides--but you'll find it far easier to create, use and modify the spreadsheet.
Interface Builder takes away a lot of completely meaningless choices ("What order should I create the objects in? How should I name the variables? How should I create their frames? What order should I set the attributes in?"), leaving you with an interface optimized for creating and arranging objects, and allowing your code to focus on what you really do need to think about--your application's logic.
(By the way--part of the reason Apple's demos don't all use Interface Builder is that the very first SDK releases didn't have it. Back then, you had to create all your views programatically. Believe me, I have no wish to go back to setting autoresize masks manually. Now get off my lawn, whippersnapper.)

Why can't I create new object from a class that is in my big class?

I mean:
class A
B x = new B;
class B
and how can I solve it if I still want to create an object from B class.
Thank you very much :)

public class ItWorksNow {
public ItWorksNow() {
public static void main ( String[] argv ) throws Exception {
ItWorksNow.DaInnaClass id = new ItWorksNow().new DaInnaClass();
public class DaInnaClass {
}

How to create unique objects in class and store

Hi, I have a class that opens a text file and reads in the
lines. each line holds an ip address. i need to create x amount of
objects, and each object is assigned a unique ip address from the file.
and here i am stuck. the class reads in the file, then i think it should create an object for each line read in and assign that object the ip address. i want to store the objects in some sort of array or collection, and i guess each object will need a unique name, but i dont know how many objects until i read in the file and count the number of lines. can anyone give me any pointers as to how i should create/store the objects
many thanx
ness

You could use your own object:
public class Test {
public class IPNumber {
    public int ip;
    public IPNumber(int ip) {
      this.ip = ip;
public Test() {
    int numberOfIPs = 5; // this is your number of lines
    IPNumber[] ips = new IPNumber[numberOfIPs];
    for (int i = 0; i < numberOfIPs; i++) ips[i] = new IPNumber(i); // assign ip address from file
public static void main(String args[]){
    new Test();
}or you could store the ips as strings:
public class Test {
public Test() {
    final int numberOfIPs = 5; // this is your number of lines
    final java.util.ArrayList al = new java.util.ArrayList(numberOfIPs);
    for (int i = 0; i < numberOfIPs; i++) al.add(""+i); // assign ip address from file
public static void main(String args[]){
    new Test();
}p.s Objects don't have names

Loading and viewing XML when a class object is created..Help Please

Hello,
I have writing a simple class which has a method that gets invoke when the object of the class is created. I am able to view the loaded XML content when I trace it with in my class method, but cannot assign the content to a instance variable using the mutator method. So the process goes like this:
Class object is instantiated
Class construtor then calls the loadXML method which laods the XML
And then assigns the XML to a class instance variable.
So now if I would like to access the loaded XML through class object, I should be able to see the loaded xml content which I am not able to see. I have spent over few hours and cannot get the class object to display the loaded XML content. I would highly appreciate it if someone can help in the right direction, please.
[code]
package com.as3.app
    import flash.display.*;
    import flash.events.*;
    import flash.text.*;
    import flash.net.*;
    public class Cars extends MovieClip {
           public var _CarList:Object;
           public function Quiz()
              super();
              loadCars();
// ===========================================================
//           CARS GETTER SETTER
// ===========================================================
        public function set Cars(val:XML):void
            this._CarList = val;
        public function get Cars():XML
            return this._CarList;
// ===========================================================
//            LOAD QUESTIONS FROM XML
// ===========================================================
        public function loadcars()
            var myXML:XML;
            var myLoader:URLLoader = new URLLoader();
            myLoader.load(new URLRequest("xml/cars.xml"));
            myLoader.addEventListener(Event.COMPLETE, processXML);
            function processXML(e:Event):void
                myXML = new XML(e.target.data);
                Cars = myXML;                 // Assigning the loaded xml data via mutator method to the _CarList;
//=============================================================
                              INSTANTIATING THE CLASS OBJECT
//=============================================================
package com.as3.app
    import flash.display.*;
    import flash.events.*;
    import flash.text.*;
    import flash.net.*;
    import com.as3.app.*;
    public class DocumentClass extends MovieClip {
        public var c:Car;
        public function DocumentClass()
            super();
            c = new Cars();
            trace(c.Cars);
[/code

where you have:
            super();
            c = new Cars();
            trace(c.Cars);
c.Cars will not trace as the loaded xml, because it will not have loaded in time. After some time it should presumably have the correct value.
loading operations in actionscript are asynchronous, so your nested function which is acting as the listener ( function processXML(e:Event):void) only ever executes when the raw xml data has loaded and that is (I believe, not 100% sure) always at least one frame subsequent to the current one.
In general I would consider it bad practise to use nested functions like that, but I don't think its contributing to your issues here. I think its just a timing issue given how things work in flash....
Additional observation:
your Cars constructor calls loadCars() and your loadCars method is defined as:
public function loadcars()
I assume its just a typo in the forum that the uppercase is missing in the function name....

Importing Class Objects created in IFS Manager into a JSP page

I create a class object using IFS Manager which consisted of extended attributes. I hope this is the right thing to do when I want to manage some extra attributes of a DOCUMENT. But the question is what package do I import to access this newly create Class Object

Thank you. The information was very helpful.
<BLOCKQUOTE><font size="1" face="Verdana, Arial, Helvetica">quote:</font><HR>Originally posted by Joyce Peng:
I believe you created a subclass of Document using iFS manager.
Your new subclass is like any other class object in iFS.
Here is an example of how to access a custom class EXPENSEREPORT with a custom attribute APPROVER.
//Gets the the collection of all the class objects.
//Then gets the specific EXPENSEREPORT class object.
Collection classObjectCollection = session.getClassObjectCollection();
ClassObject expenseReportClassObject =
(ClassObject) classObjectCollection.getItems("EXPENSEREPORT");
//Gets the APPROVER attribute for the class object.
Attribute attribute = expenseReportClassObject.getEffectiveClassAttributes("APPROVER");
<HR></BLOCKQUOTE>
null

TestStand create different object for singleton class

Hi all,
we have a singleton class which has some functions used to do testing a harware.
Our main Exe will create an object for that singleton class(which opens Com1 port and communicate with hardware). so the Exe will do basic communication test with hardware it is working well. We are using Teststand operator interface to do various testing by using sequence files. Main exe will use teststand usercontrols to execute tests when the user clicks Testbutton. after that, teststand try to create an object for that singleton but it returns new object not the existing one which is created by EXE. So it throwing me exeception "Com1 port access denied." (since we created object for signleton class @ very first in EXE)
My question is Since that teststand runs in a separate Appdoamin will the singltonclass create separate object for different appdomain? if so is there any solution to reslove this?
Hope i clearly explained my probs.
Thanks in advance
Srini

Hi Srini,
How are you calling the executable? From a Call Executable step? Or are you using another means of calling it? Also, why is TestStand trying to recreate the object? As long as you have the correct handle to the object I don't think it matters what app domain you are in.
Regards,
jigg
CTA, CLA
teststandhelp.com
~Will work for kudos and/or BBQ~

Can I create a Class object without the VM?

Using byte-code engineering, is it possible to create a class object?
What about if I serialize a Class object to a file, can I byte-code engineer that and then reinstantiate it?

Thanks I'll check it out. Basically I want to try it
for fixing a problem of running two apps in the same
VM.There's a world of problems when you try to run two programs within the same JVM. I wouldn't suggest even trying it unless it's a last resort. Why do you want to do that?

How to create an object of a class?

plz read the question carefully ..
how to create the object of a class by giving the class name as an String
suppose i have a java file name:" java1.java ".
so now how to create an object of this class "java1"by passing a string "java1"..

kajbj wrote:
rajeev-usendi wrote:
thanks but still i have problem..
i have created the object but now i m unable to do anything with that created object..
i have coded like this..
Object o= Class.forName("java1").new Instance();
after this i m unable to do anything with the object 'o'..So why did you create the instance? You can also get all methods using reflection, but that is probably not what you want to do. You should instead let the class implement an interface and cast the created object into that interface ans call the methods that you want to call.
KajI agree with Kaj. If you need to use a class that's unavailable at compile time, you should create an appropriate interface by which to refer to the class and then you create instances reflectively and access them normally via their interface (which is called reflective instantiation with interface access)

How to create an object class programmatically?

Guys,
I need your help. If possible with a simple example of how to do it.
I need to create an aplication that read an specification of a repository type from a file and then creates it inside my BEA Repository. The problem are few:
1 - How to Create an Object Class programmaticaly?
I looked at documentation of ObjectClassOps but havent figured out how to do it.
2 - How to Create a Property Definition programmaticaly?

Sorry, ITypeManager only exists in 9.2. If you are working on 8.1, then the previous example becomes:
RepositoryManager repositoryMgr = RepositoryManagerFactory.create();
//connect to the repository
repositoryMgr.connect();
//get ObjectClassOps
ObjectClassOps ocops = repositoryMgr.getObjectClassOps();
ID repId = new ID();
repId.setRepositoryName(repositoryName);
PropertyDefinition[] pds = new PropertyDefinition[1];
pds[0] = new PropertyDefinition(repId, "stringProp", null, Property.STRING, false, false, false, false, false, null);
ObjectClass oc = new ObjectClass(repId, "myType", null, pds);
oc = ocops.createObjectClass(oc);

Creating class objects

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