user384706 - Developer IT

add jsf project facet in eclipse/ why need it?

- by user384706

Hi, I started on JSF2.0. I followed a tutorial with no problem and all worked fine! I used Eclipse Helios. But I noticed something I can not understand. The tutorial said to add Project Facet for JSF 2. I did no such thing and all worked ok. So to follow tutorial exactly I did: Right-click on Project -Properties- Project Facets And JavaServer Faces check-box was not ticked. I assume this is what the tutorial means by Project Facet. I clicked on it and a Further Configuration Needed link appeared. I followed the link to a JSF capabilities (Modify Faceted Project) dialog, I selected as User library, my library of JSF(which is MyFaces) but I got the error message: Found multiple versions of the required class javax.faces.FactoryFinder. What is this error? Can't I add project facet after creating my project? And what do I need the project facet for? My (trivial) code indicates that JSF works ok, so what is the project Facet useful for? Thanks!

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java 2D and swing

- by user384706

Hi, I have trouble understanding a fundamental concept in Java 2D. To give a specific example: One can customize a swing component via implementing it's own version of the method paintComponent(Graphics g) Graphics is available to the body of the method. Question: What is exactly this Graphics object, I mean how it is related to the object that has the method paintComponent? Ok, I understand that you can do something like: g.setColor(Color.GRAY); g.fillOval(0, 0, getWidth(), getHeight()); To get a gray oval painted. What I can not understand is how is the Graphics object related to the component and the canvas. How is this drawing actually done? Another example: public class MyComponent extends JComponent { protected void paintComponent(Graphics g) { System.out.println("Width:"+getWidth()+", Height:"+getHeight()); } public static void main(String args[]) { JFrame f = new JFrame("Some frame"); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); f.setSize(200, 90); MyComponent component = new MyComponent (); f.add(component); f.setVisible(true); } } This prints Width:184, Height:52 What does this size mean? I have not added anything to the frame of size(200,90). Any help on this is highly welcome Thanks

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jsf flash.keep and redirects does not seem to work

- by user384706

Hi, I am trying to use JSF 2.0 flash via redirects. I have a class named UserBean (ManagedScoped and RequestScoped). It has a method called getValuesFromFlash which essentially gets the values from the flash and sets the coresponding properties of the UserBean public void getValuesFromFlash() { Flash flash = FacesContext.getCurrentInstance().getExternalContext().getFlash(); firstName= (String) flash.get("firstName"); lastName = (String) flash.get("lastName"); } In the entry page the <h:inputText> are bound to the flash. Snippet follows: Entry.xhtml <h:form> <table> <tr> <td>First Name:</td> <td> <h:inputText id="fname" value="#{flash.firstName}" required="true"/> <h:message for="fname" /> </td> </tr> <tr> <td>Last Name:</td> <td> <h:inputText id="lname" value="#{flash.lastName}" required="true"/> <h:message for="lname" /> </td> </tr> </table <p><h:commandButton value="Submit" action="confirmation?faces-redirect=true" /></p> </h:form> In confirmation.xhtml these values are supposed to be displayed but they are not. Snippet follows: <table> <tr> <td>First Name:</td> <td> <h:outputText value="#{flash.keep.firstName}" /> </td> </tr> <tr> <td>Last Name:</td> <td> <h:outputText value="#{flash.keep.lastName}"/> </td> </tr> </table> <h:form> <p><h:commandButton value="Confirm" action="finished?faces-redirect=true" /></p> </h:form> In finished.xhtml I want all these to be displayed so: <h:body> <h:form> #{userBean.getValuesFromFlash( )} <table> <tr> <td>First Name:</td> <td> <h:outputText value="#{userBean.firstName}" /> </td> </tr> <tr> <td>Last Name:</td> <td> <h:outputText value="#{userBean.lastName}"/> </td> </tr> </table> </h:form> </h:body> Instead when I get redirected to confirmation.xhtml neither first nor last name is displayed, despite I used flash.keep Also in finished.xhtml I get org.apache.el.parser.ParseException: Encountered " "(" "( "" at line 1, column 30. Was expecting one of: "}" ... "." If I remove the parenthesis from the expression #{userBean.getValuesFromFlash( )} and make it = #{userBean.getValuesFromFlash} javax.el.ELException: /done.xhtml: Property 'getValuesFromFlash' not found on type com.UserBean But why no property??It is a method! Why is the method not visible? What I am doing wrong here please? I am using JSF2.0 (MyFaces), Eclipse Helios and Tomcat 6 (Have also tried in Tomcat 7 but no luck). Any help is appreciated. Thanks!

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java keytool question

- by user384706

Hi, I created a java keystore programmatically of type jks (i.e. default type). It is initially empty so I created a DSA certificate. keytool -genkey -alias myCert -v -keystore trivial.keystore How can I see the public and private keys? I.e. is there a command that prints the private key of my certificate? I could only find keytool -certreq which in my understanding prints the certificate as a whole: -----BEGIN NEW CERTIFICATE REQUEST----- MIICaTCCAicCAQAwZTELMAkGA1UEBhMCR1IxDzANBgNVBAgTBkdyZWVjZTEPMA0GA1UEBxMGQXRo BQADLwAwLAIUQZbY/3Qq0G26fsBbWiHMbuVd3VICFE+gwtUauYiRbHh0caAtRj3qRTwl -----END NEW CERTIFICATE REQUEST----- I assume this is the whole certificate. How can I see private (or public key) via keytool? Thank you

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java string detection of ip

- by user384706

Hi, Assume a java string that contains an IP (v4 or v6) or a hostname. What is the best way to detect among these cases? I am not interested so much on whether the IP is in valid range (e.g. 999.999.999.999 for IPv4). I am interested in just a way to detect if a String is a hostname or an IP (v4 or v6). Initially I though this: if(theString.indexOf("@")!=-1){ //Not an Ip } but I am not sure if I should always expect a format containing @ always. Thanks

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How to find longest common substring using trees?

- by user384706

The longest common substring problem according to wiki can be solved using a suffix tree. From wiki: The longest common substrings of a set of strings can be found by building a generalised suffix tree for the strings, and then finding the deepest internal nodes which have leaf nodes from all the strings in the subtree below it I don't get this. Example: if I have: ABCDE and XABCZ then the suffix tree is (some branches from XABCZ omitted due to space): The longest common substring is ABC but it is not I can not see how the description of wiki helps here. ABC is not the deepest internal nodes with leaf nodes. Any help to understand how this works?

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java statistics collection for performance evaluation

- by user384706

What is the most efficient way to collect and report performance statistic analysis from an application? If I have an application that uses a series of network apis, and I want to report statistics at runtime, e.g. Method doA() was called 3 times and consumed on avg 500ms Method doB() was called 5 times and consumed on avg 1200ms etc Then, I thought of using a well defined data structure (of collection) that each thread updates per remote call, and this can be used for the report. But I think that it will make the performance worse, for the time spend for statistics collection. Am I correct? How would I procceed if I used a background thread for this, and the other threads that did the remote calls were unaware of this collection gathering? Thanks

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Problem in packages in importing in Eclipse

- by user384706

Hi (I am using Galileo), I am trying to import some existing projects into Eclipse. The structures for their packages is: Project/ /src /java /a /b /c Once imported in the package explorer I see: Project src/java --a --b --c - AClass.java This is ok, since the classes e.g. AClass.java are defined in package: a.b.c But in one project the structure (once imported) becomes: Project src --java --a --b --c - AClass.java And that causes the error that AClass.java is defined to be in package a.b.c but it is actually under java.a.b.c Why is this happening? Why in this specific project java is not ignored as part of package? Thanks

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jsf and eclipse setup. Lib in Explorer is different than lib in tomcat. How come?

- by user384706

Hi, I am starter in JSF2.0, and I have a question related to Eclipse (I am using Helios). 1)I create a Dynamic Project 2)I add JSF project facet. 3)I choose JSF user library (I have created it using MyFaces) All ok so far. I notice though that in the Project Explorer in WebContent/WEB-INF/lib the lib directory is empty instead of having MyFaces jars. The application works fine though. I looked into this and the jars are actually being placed in the corresponding lib directory of the app deployed under wtpwebapps of the Tomcat instance of eclipse in the .pluggins directory. Ok, it works but IMHO it is incorrect to have the Project Explorer inconsistent with the directories actually deployed. I.e. lib is shown empty in Project Explorer but with jars under wtpwebapps. Am I wrong to dislike this inconsistency? Is this how it should work or am I doing something wrong in the way I am setting my project? Thanks!

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