Conversion of Java Generics to JavaFX sequence in Java Program

I have created a TwitterFetcher.java which collects the latest 20 tweets and generates a List<TwitterUpdate>
I know that I have to convert this Java List into a JavaFX Sequence using Sequences.
Have tried quite a few variations with Sequences.make(...) but to no avail.
following is the code:
import com.sun.javafx.runtime.sequence.Sequence;
import com.sun.javafx.runtime.sequence.Sequences;
import java.util.Iterator;
import org.w3c.dom.TypeInfo;...
List<TwitterUpdate> ltu = new ArrayList<TwitterUpdate>();
TwitterUpdate tu = new TwitterUpdate();
Sequence<? extends TwitterUpdate> stu;
public Sequence<TwitterUpdate> getUpdates()
for (Status status : api.getFriendsTimeline())
tu.setName(status.getUser().getName());
tu.setScreenName(status.getUser().getScreenName());
tu.setImgURL(status.getUser().getProfileImageUrl());
tu.setTweet(status.getText());
tu.setDate(status.getCreatedAt().toDate().toString());
ltu.add(tu);
//convert the List to a Sequence
//return the sequenceAm I missing a step or two or doing something completed wrong.??
I really have to get this done..

We are actually following MVC architecture, where in our back end is totally in Java and the rendering is handled in JavaFX..
Hence interop between the two was extremely important..
and the problem was that...
in our JavaFX project...we have packages with only java files and other packages with only JavaFX package..
So whilst importing packages in a JavaFX classes..we can recognize our own java and javafx files...
But whilst in Java classes..recognition of Javafx packages is not possible....
Hence sharing Data structures between the two was difficult...
So we ended up making POJOs..and ported that in JavaFX classes as it was able to recognize Java objects...
We are now using concept of Array of objects and passing it to JavaFX classes as return type..
Regards
Kaustubh

Similar Messages

Need help wiith java generics

I have written a java program using jdk1.5. After completing my program I noticed that the compiler was outputting a warning. It tells me that there were a few unsafe operations in my code. Anyway I found out that my code needed to include generics. I was able to figure out how too include some of the generics. I am having trouble with the following:
[javac] /home/paul/Documents/java/PersonalInfo/src/personalInfo/logic/DB.java:105: warning: [unchecked] unchecked conversion
[javac] found : personalInfo.logic.FNComparator
[javac] required: java.util.Comparator<? super java.lang.Object>
[javac] Arrays.sort(sort, fn);
[javac] ^
[javac] /home/paul/Documents/java/PersonalInfo/src/personalInfo/logic/DB.java:105: warning: [unchecked] unchecked method invocation: <T>sort(T[],java.util.Comparator<? super T>) in java.util.Arrays is applied to (java.lang.Object[],personalInfo.logic.FNComparator)
[javac] Arrays.sort(sort, fn);
[javac] ^
[javac] /home/paul/Documents/java/PersonalInfo/src/personalInfo/logic/DB.java:109: warning: [unchecked] unchecked conversion
[javac] found : personalInfo.logic.LNComparator
[javac] required: java.util.Comparator<? super java.lang.Object>
[javac] Arrays.sort(sort, ln);
[javac] ^
[javac] /home/paul/Documents/java/PersonalInfo/src/personalInfo/logic/DB.java:109: warning: [unchecked] unchecked method invocation: <T>sort(T[],java.util.Comparator<? super T>) in java.util.Arrays is applied to (java.lang.Object[],personalInfo.logic.LNComparator)
[javac] Arrays.sort(sort, ln);
[javac] ^
The FN/LNComparator class implements the java.util.Comparator class. I have looked at the generics tutorial on the java.sun.com website. I can't figure out what I replace the <T> with to make the code compile and the warning to go away. I have tried <Comparator> but that just gives me an error that says FNComparator does not take any parameters.
If anyone knows how to fix these warnings let me know
-Hockeyfan

You'll probably get an answer here, as a lot of people read this forum and at least some of them know generics pretty well. For future reference though, there's a forum here devoted to generics, and I know that at least one of Sun's generics implementors answers questions there, so that's probably better place to post generics questions.

One thing java generics are missing

specialization!
I'll give you a templated example with a function here:
template <typename T>
inline std::string to_string(const T& t)
std::istringstream ss;
ss << t;
return ss.str();
that's one of those standard conversion snippets that everyone uses... as long as T supports the "<<" operator, it will convert just fine...
Now, if you're using this function in other template based code, the problem comes up:
template <typename T>
void foo(const T& t)
std::string s = to_string(t);
... do something with s now...
it makes sense, if you want to do operations with a string... but what if the type T *was* a string... the to_string function just did a whole mess of needless operations (stringstream conversion)...
here comes template specialization to the rescue:
template <> inline std::string to_string<std::string>(const std::string& t)
return t;
there we go... no extra steps... because it's inlined to begin with, the compiler will remove it... (this is what's called a conversion shim). Now when the to_string function is called with an std::string argument, it does nothing.

Hmmm, it seems I didn't explain it too well:
the 3rd snippit is the same as the first, however the "typename T" has been removed and all instances of "T" have been replaced with a specific type: this is template specialization... it allows for you to have different code for each type... it's a complicated form of function overloading....
what I'm saying is that, in a java generic collection, you may have all this code that works for all types, but could be optimized for one of those types... I used string above...
for instance... let's say there's a member function to count the number of characters used if the type were converted to a string... the easiest thing to do would be to convert it to a string an get the length.... however, in the case of numbers, there's a much, much more efficient way to do it (can't recall the algorithm... but you can get the number of digits with division and maybe a log10 or something...)... this is a mundane case, but even if you did want to use that math for the int version of that generic, you couldn't...

Can someone help me understand this? (java generics wildcards)

Hi all.
First of all this is my first post on sun forums. Besides that i only used java for few weeks now and i think java is quit a nice language.
I do have a question regarding java generics and wildcard casting (if you can call it that).
Assume you have following code.
public class Test <T extends Number> {
     private T x;
     Test(T x)
          this.x = x;
     T getX()
          return x;
     <U extends Number> void setX(U x)
          this.x = (T)x;
public class Main {
     public static void main(String[] args) {
          Test<Integer> p = new Test <Integer>(5);
          System.out.println(p.getX());
          p.setX(53.32);
          System.out.println(p.getX());
}This compiles with following results:
5
53.32
Question:
First: If I declared p to be of type Test<Integer> then why did x in Test class changed its type from Integer to Double?
Second: Is this a possible unchecked casting behavior? and if so why does this work but doing something like this :
Integer x = 5 ;
Double y = 6.32;
x=(Integer)y;fails with compile time error?

Hello and welcome to the Sun Java forums.
The behavior you describe would not occur if your setX(?) method used T instead of another type constraint.
However, let's look at why it works!
At line 1 in main, you create your Test with a type parameter of Integer; this becomes the type variable T for that particular instance of Test. The only constraint is that the type extends/implements Number, which Integer does.
At line 2 you obtain a reference to a Number, which is what getX() is guaranteed to return. toString() is called on that object, etc.
At line 3 you set the Number in the Test to a Double, which fits the type constraint U extends Number, as well as the type constraint T extends Number which is unused (!). Note that using a different type constraint for U, such as U extends Object or U super Number, could cause a compile-time error.
At line 4 you obtain a reference to a Number, which is what getX() is guaranteed to return.
The quirky behavior of setX is due to the second type constraint, which is obeyed separately; in this case, you probably want to use void setX(T x) {
this.x = x;
}edit: For the second part of your question, x = (Integer)y; fails because Integer and Double are distinct types; that is, Integer is not a subclass of Double and Double is not a subclass of Integer. This code would compile and work correctly: Number x = 5 ;
Double y = 6.32;
x=y;s
Edited by: Looce on Nov 15, 2008 7:15 PM

How to pass Objects from Java App to JavaFX Application

Hello,
New to the JavaFX. I have a Java Swing Application. I am trying to use the TreeViewer in JavaFX since it seems to be a bit better to use and less confusing.
Any help is appreciated.
Thanks
I have my Java app calling my treeviewer JavaFX as
-- Java Application --
public class EPMFrame extends JFrame {
Customer _custObj
private void categoryAction(ActionEvent e)   // method called by Toolbar
        ocsCategoryViewer ocsFX;    //javaFX treeviewer
        ocsFX = new ocsCategoryViewer();    // need to pass in the Customer Object to this Not seeing how to do it.
                                              // tried ocsFX = new ocsCategoryViewer(_custObj) ;    nothing happened even when set this as a string with a value
public class ocsCategoryViewer extends Application {
String _customer;
@Override
    public void start(Stage primaryStage) {
     TreeView <String> ocsTree;
     TreeItem <String> root , subcat;
TreeItem <String> root = new TreeItem <String> ("/");
        root.setExpanded(true);
         ocsTree = new TreeView <String> (root);
         buildTree();     // this uses the Customer Object.
        StackPane stkp_root = new StackPane();
        stkp_root.getChildren().add(btn);
        stkp_root.getChildren().add(ocsTree);
        Scene scene = new Scene(stkp_root, 300, 250);
        primaryStage.setTitle("Tree Category Viewer");
        primaryStage.setScene(scene);
        primaryStage.show();
    public static void main(String[] args) {
        _customer = args[0];      // temporarily trying to pass in string.
        launch(args);

JavaFX and Swing integration is documented by Oracle - make sure you understand that before doing further development.
What are you really trying to do? The answer to your question depends on the approach you are taking (which I can't really work out from your question). You will be doing one of:
1. Run your Swing application and your JavaFX application as different processes and communicate between them.
This is the case if you have both a Swing application with a main which you launch (e.g. java MySwingApp) and JavaFX application which extends application which you launch independently (e.g. java MyJavaFXApp).
You will need to do something like open a client/server network socket between the applications and send the data between them.
2. Run a Swing application with embedded JavaFX components.
So you just run java MySwingApp.
You use a JFXPanel, which is "a component to embed JavaFX content into Swing applications."
3. Run a Java application with embedded Swing components.
So you just run java MyJavaFXApp.
You use a SwingNode, which is "used to embed a Swing content into a JavaFX application".
My recommendation is:
a. Don't use approach number one and have separate apps written in Swing and Java - that would be pretty complicated and unwarranted for almost all applications.
b. Don't mix the two toolkits unless you really need to. An example of a real need is that you have a huge swing app based upon the NetBeans platform and you want to embed a couple of JavaFX graphs in there. But if your application is only pretty small (e.g., it took less than a month to write), just choose one toolkit or the other and implement your application entirely in that toolkit. If your entire application is in Swing and you are just using JavaFX because you think its TreeView is easier to program, don't do that; either learn how to use Swing's tree control and use that or rewrite your entire application in JavaFX. Reasons for my suggestion are listed here: JavaFX Tip 9: Do Not Mix Swing / JavaFX
c. If you do need to mix the two toolkits, the answer of which approach to use will be obvious. If you have a huge Swing app and want to embed one or two JavaFX components in it, then use JFXPanel. If you have a huge JavaFX app and want to embed one or two Swing components in it, use a SwingNode. Once you do start mixing the two toolkits be very careful about thread processing, which you are almost certain screw up at least during development, no matter how an experienced a developer you are. Also sharing the data between the Swing and JavaFX components will be trivial as you are now running everything in the same application within the virtual machine and it is all just Java so you can just pass data around as parameters to constructors and method calls, the same way you usually do in a Java program, you can even use static classes and data references to share data but usually a dependency injection framework is better if you are going to do that - personally I'd just stick to simply passing data through method calls.

Problem with Java-Packages in JavaFX-Scripts

Hello!
What I'm trying to do is using a class I've built in my project in a JavaFX-Script, my problem is that the compiler keeps telling me my package wouldn't exist.
My filestructure is basically the following:
src
|-com.foo.java
|-- MyClass.java
|-com.foo.javafx
|-- MyFXScript.fx
I've tried importing the package or just writing the fully qualified classname when trying to create an instance, the messages didn't differ. I'm not at home right now so I don't remember the exact compiler-message, but it was something like "Package does not exist: com.foo.java".
Any ideas? :-)
Kind regards,
Joshua
Edited by: gnrx on Jan 12, 2009 5:55 AM

It works on my system.
MyClass.java
package com.foo.java;
public class MyClass {
    @Override
    public String toString() {
        return "My Class";
MyFXScript.fx
package com.foo.javafx;
import com.foo.java.*;
var myClass = new MyClass();
println(myClass);standard-run:
My Class
browser-run:
jws-run:
midp-run:
run:
BUILD SUCCESSFUL (total time: 3 seconds)

How to implement a java class in javafx?

public interface WarningEvent {
    public void warningHandler ();
function test ():Void {
        var warningEvent:WarningEvent = new WarningEvent() {
            public void warnHandler(){
    }I am trying to implement java method inside javafx, but without luck. I also tried override with javafx syntax, but still cannot get it. Any one could help on this?
Thanks.

1) Get rid of the keyword new
2) Get rid of braces ()
3) For the function declaration, use the JavaFX syntax, not the Java syntax!
function test ():Void {
        var warningEvent:WarningEvent = WarningEvent {
            override public warnHandler():Void {
}Your class need to have a default constructor (the one without any argument) to be able to do this (and in this case it works because you have an interface instead).

How to represent java generics in UML

Hello,
Can anyone tell me how to represent java generics in UML? Say I have ClassA<ClassB>. How do I represent this in UML?
Thanks in advance,
Julien Martin.

More formally you can use parameterized types.
: T:Classifier :
+---------:..............:
| ClassA |
<<bind>> <T -> ClassB>
| ClassA<ClassB> |
Which may be useful if you have different instantiations of ClassA<T> with different values of T.
Pete
(I really must get round to making an ascii art UML editor sometime)

Java API of javafx?

Hi,
Is there some kind of Java API of javafx? I don't want to learn javafx's scripting language, and although I understand Sun's decision to give a scripting interface, I don't want to learn it b/c it will make me violently vomit. Unfortunately javafx apps look gorgeous and integrate well with 3rd party graphics design apps.
All javafx code gets compiled into a .class file anyway, so the API should be available, right? Where can I find it? Or is it still under active development and not yet released?
Thanks,
Mark

You can call Java code directly from JavaFX if you really want to subvert it, however as others have stated you will certainly have to learn the new syntax to take full advantage of it. As a personal aside, I've found that much of what JavaFX offers isn't readily available in Java. Granted, certain libraries exist that are analogous to what JavaFX is trying to accomplish (like http://processing.org/) but I've found JavaFX to be much easier to get the hang of. Having said all that, I agree that they should have maintained similarities between Java and JavaFX like the use of && instead of AND and the way loops are iterated but really there are only a handful of new syntax. Don't forget, JavaFX is not procedural and Java is (generally) and much of the new syntax reflects that, while also paying tribute to some other popular technologies like actionScript and JavaScript.
All things considered, I think they choose well and produced something that seamlessly works with Java but is appealing to developers from Java and non-Java backgrounds alike. Personally, I picked up Java and JavaFX at the same time and despite the differences I haven't had any real syntax confusion.

A RCP Application using javafx deployed by java web start,in jre8u25 run have problem.

a RCP Application using javafx deployed by java web start,in jre8u20 can use jre7run the applicat,but in jre8u25 use jre7run application have problem.
in jre8u20 use jre7 run the application can run success.
but in jre8u20 the control print:
java.lang.UnsupportedClassVersionError: com/sun/javafx/runtime/VersionInfo : Unsupported major.minor version 52.0
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.access$100(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at com.sun.deploy.config.JfxRuntime.runtimeForPath(Unknown Source)
at com.sun.deploy.config.JREInfo.<init>(Unknown Source)
at com.sun.deploy.config.JREInfo.setInstalledJREList(Unknown Source)
at com.sun.deploy.config.ClientConfig.storeInstalledJREs(Unknown Source)
at com.sun.javaws.Main.launchApp(Unknown Source)
at com.sun.javaws.Main.continueInSecureThread(Unknown Source)
at com.sun.javaws.Main.access$000(Unknown Source)
at com.sun.javaws.Main$1.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
the reason (i think) is that the application will use javafx's com.sum.javafx.runtime.VersionInfo,i use e(fx)clipse load the javafx runtime.in jre8u20,the web start use jre7's class.in jre8u25,the web start use jre8's class.
so i use jre7 run the application get this result.
how could i solve this problem?

Hi,
I have created client stubs for a webservice using axis wsdl2java tool. When I try calling these stubbed methods from JUnit tests, they are working fine but when I try to execute the jar (it is a swing) I get the following exception:
Exception in thread "main" java.lang.NoClassDefFoundError: javax/xml/rpc/Service
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.access$100(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClassInternal(Unknown Source)
at com.Gudds.SeCURE.MainUI.<init>(MainUI.java:76)
at com.Gudds.SeCURE.Main.Start(Main.java:62)
at org.owasp.webscarab.WebScarab.main(WebScarab.java:34)
I have put the jaxrpc.jar in the classpath and I suppose this jar has the java.xml.rpc.service class but I donot understand why it fails while executing the jar but works fine from the eclipse IDe. Plase help me.
Regrdas,
Kundan

Handling/passing Java exceptions to JavaFX

My Java class has a try/catch statement indicating a communication error to MySQL server. I want to add a user-friendly dialog box in my JavaFX application in the event my java class cannot access the database.
What's the best way of handling Java exceptions within JavaFX?
Cheers!

Rethrow an exception and catch it in the call in JavaFX code?

New to JavaFX--Calling Java objects from JavaFX

Hello,
I am a Java developer who is new to JavaFX. I am having no luck in finding a tutorial that exhibits more than just fun effects. I need to be able to call existing classes from a JavaFX GUI. Can anyone offer any assistance on this? It's very frustrating because this should be a simple task. If we are faced with having to rewrite existing code, we will probably be forced to abandon JavaFX. I hope this is not the case.
Thanks!

The answer is yes. The impementation is -
If you have classes that you keep as library classes that you intend for use irrespective of the platform, then I suspect that you have already written them with no view content. For those, including them in your JavaFX is not really different to using them in Java. I am just learning JavaFX too and the most important lesson for us to learn is that 'JavaFX is Java with FX on the end of it'. I know the strickly come dancing set will say 'oh but what about types'. Well I have found no trouble at all with types, basic or my own, we are in object world so long as the compiler has the class object and we have all stuck to the rules then it has all it needs to act on your objects.
So your non-View classes can be used as you always use them -
import mylib'
var somethingFromMyLibOfClasses = new mylib.ClassThatDoesSomethingVeryClever();
It is then just a matter of arranging a FX trigger of some kind (trigger/event/timer/bind) to call the function in your library.
Which triggers and when are the part I am still finding difficult. The basic GUI events are fine (onMouseClick etc), it is 'bind' that is troublesome.
Binding something in your code to a 'property' of the display element is easy enough, but binding where you have no external variable that relates to 'Property' value is less clear. For example you may have to change a form contents due to a trigger sent from a remote database.
You have some in the forum talking of 'resize your window a few pixels to force a redraw so that your code can be retriggered'. Others are using timers at high tick frequency to for an update. such as changing a property that you can't see.
That is utter nonsense, if you look up the proper description of bind then it becomes obvious. Bind can be a two way thing, you can change a value in your element from outside, but you can also change a value outside of your element from within your element.
Equally that trigger can be your own code. There is no need of trickery to update Scenes, the writters of JavaFX already have it sussed.
The Sun web site has some great tutirials, but as a personal favourite that cleared up som of the junk about JavaFX that was building up in my mind I reccommend you spend a bit of time here [JavaFX Refference|http://openjfx.java.sun.com/current-build/doc/reference/JavaFXReference.html]
Not the best layout you will ever see, but it is the best source I have found, then if you use that along side [Master Index|http://java.sun.com/javafx/1.2/docs/api/javafx.stage/javafx.stage.Stage.html] hopefully you will find, as I did, that you do not have to think differently to make use of the FX on the end of Java.

Start JavaFX application from Java

Hello,
I have the following scenario:
I have a small JavaFX application and a big Java application. Now the Java App should call the JavaFX App to start up.
Further the JavaFX App has to call some methods from the Java App. Is this possible?
What is the best approach for my scenario?
Maybe somebody has made some experiences ..
thanks!
Edited by: 799878 on 03.11.2010 07:54

"Now the Java App should call the JavaFX App to start up."
I'm assuming that the JavaFX code and the Java code are in the same application, correct? If so, then there are hacks available, but no standard way to start up JavaFX from Java will exist until the APIs have been ported from JavaFX script to Java.
"Further the JavaFX App has to call some methods from the Java App. Is this possible?"
Yes. Java can be called from JavaFX just fine. Just be careful if you use multi-threading or time consuming operations, since JavaFX script is apparently single threaded. Also be aware that netbeans normally compiles JavaFX applications with JSE version 1.5, so library features that did not exist until later versions will not be available by default.

How can i merge javafx code and java fxml code in a single project

how can i merge javafx code and java fxml code in a single project.
Please let me Know as soon as possible.

Everything that it is possible to retrieve from a class file can be deduced from the class file definition.
http://java.sun.com/docs/books/vmspec/2nd-edition/html/ClassFile.doc.html
Sylvia.

Difference between Java applet and JavaFX

Hello, all!
I am studying javaFX in general. As far as I understand there is no main difference between java applet and javafx, except javafx has different syntax and library simple to use. Is it right?

Basically, yes. But as you point out, it is supposed to be faster to develop in JavaFX...
For example, Processing allows to export to applet, and is strong on doing graphics, but to see if user has clicked on a circle, you have to check the mouse coordinates against the circle coordinates, or create your own Circle class: it is at a much lower level.
Likewise, you can use gaming frameworks like Slick2D or PulpCore, but they might be lacking on GUI (but perhaps faster). Or use Apache's Pivot, strong on GUI, but perhaps lacking a bit on graphics and animation.
It depends on your needs, if you prefer to stick to Java, etc.

Conversion of Java Generics to JavaFX sequence in Java Program

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