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  • Direct flow depending on incoming dynamic type

    - by Improfane
    I have a listener class that accepts GUI change events in one method. The incoming event objects have a superclass of a type of GUI Event, the behaviour should depend on the dynamic type of the incoming variable. I wanted to do do lots of methods like: handleGUIEvent(EventChangedX event) handleGUIEvent(EventChangedY event) I am using a single event listener and receiving objects of various types but the behaviour should be different for each. What would you do? I do not want to use a switch statement as this would get unmaintainable.

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  • Android - save/restore state of custom class

    - by user1209216
    I have some class for ssh support - it uses jsch internally. I use this class on main activity, this way: public class MainActivity extends Activity { SshSupport ssh = new SshSupport(); ..... @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); //Handle events for ssh ssh.eventHandler = new ISshEvents() { @Override public void SshCommandExecuted(SshCommandsEnum commandType, String result) { } //other overrides here } //Ssh operations on gui item click @Override public void onItemClick(AdapterView<?> arg0, View v, int position, long arg3) { if (ssh.IsConnected() == false) { try { ssh.ConnectAsync(/*parameters*/); } catch (Exception e) { e.printStackTrace(); } } try { ssh.ExecuteCommandAsync(SshCommandsEnum.values()[position]); } catch (Exception e) { e.printStackTrace(); } } }); } It works very well. My application connects to ssh, performs all needed operation in background thread and results are reported to gui, via events as shown above. But nothing works after user change device orientation. It's clear for me - activity is re-created and all state is lost. Unfortunately, my SshSupport class object is lost as well. It's pretty easy to store gui state for dynamically changed/added objects (using put/get serializable etc methods). But I have no idea how to prevent my ssh object, ssh connected session being lost. Since my class is not serializable, I can't save it to bundle. Also, even if I make my SshSupport class serializable, jsch objects it uses still are not serializable. So what is the best way to solve this?

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  • Set request attributes when a Form is POSTed

    - by ssahmed555
    Is there any way to set request attributes (not parameters) when a form is posted? The problem I am trying to solve is: I have a JSP page displaying some data in a couple of dropdown lists. When the form is posted, my Controller servlet processes this request (based on the parameters set/specified in the form) and redirects to the same JSP page that is supposed to display addition details. I now want to display the same/earlier data in the dropdown lists without having to recompute or recalculate to get that same data. And in the said JSP page, the dropdown lists in the form are populated by data that is specified through request attributes. Right now, after the Form is POSTed and I am redirected to the same JSP page the dropdown lists are empty because the necessary request attributes are not present. I am quite the n00b when it comes to web apps, so an obvious & easy solution to this problem escapes me at the moment! I am open to suggestions on how to restructure the control flow in the Servlet. Some details about this app: standard Servlet + JSP, JSTL, running in Apache Tomcat 6.0. Thanks.

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  • "No row with the given identifier exists" although it DOES exist!

    - by roesslerj
    Hello all! I am using Hibernate and getting Exception in thread "main" org.hibernate.ObjectNotFoundException: No row with the given identifier exists: [<MyDbObject>#271] What is pretty weird about this error is, that the object with the given id exists in the database. I inserted the problematic record in another run of the application. If I access it in the same run (i.e. same hibernate session) there seem to be no problems retrieving the data. Just because it could be a fault of the mapping: public class ProblemClass { @ManyToOne(optional = false) private MyDbObject myDbObject; } public class MyDbObject { @OneToMany(mappedBy = "myDbObject") private List<ProblemClass> problemClasses; } I have absolutely no clue even where to look at. Any hints highly appreciated!

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  • Making an efficient algorithm

    - by James P.
    Here's my recent submission for the FB programming contest (qualifying round only requires to upload program output so source code doesn't matter). The objective is to find two squares that add up to a given value. I've left it as it is as an example. It does the job but is too slow for my liking. Here's the points that are obviously eating up time: List of squares is being recalculated for each call of getNumOfDoubleSquares(). This could be precalculated or extended when needed. Both squares are being checked for when it is only necessary to check for one (complements). There might be a more efficient way than a double-nested loop to find pairs. Other suggestions? Besides this particular problem, what do you look for when optimizing an algorithm? public static int getNumOfDoubleSquares( Integer target ){ int num = 0; ArrayList<Integer> squares = new ArrayList<Integer>(); ArrayList<Integer> found = new ArrayList<Integer>(); int squareValue = 0; for( int j=0; squareValue<=target; j++ ){ squares.add(j, squareValue); squareValue = (int)Math.pow(j+1,2); } int squareSum = 0; System.out.println( "Target=" + target ); for( int i = 0; i < squares.size(); i++ ){ int square1 = squares.get(i); for( int j = 0; j < squares.size(); j++ ){ int square2 = squares.get(j); squareSum = square1 + square2; if( squareSum == target && !found.contains( square1 ) && !found.contains( square2 ) ){ found.add(square1); found.add(square2); System.out.println( "Found !" + square1 +"+"+ square2 +"="+ squareSum); num++; } } } return num; }

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  • How to inspect JSP request URL for String

    - by IAmYourFaja
    I have the following processor.jsp file: <% response.sendRedirect("http://buzz.example.com"); %> I want to change it so that it inspects the HTTP request URL for the presence of the word "fizz" and, if it exists, redirect the user to http://fizz.example.org instead. So something like: <% String reqUrl = request.getURL().toLowerCase(); String token = null; if(reqUrl.contains("fizz")) { token = "fizz"; } else { token = "buzz"; } String respUrl = "http://%%%TOKEN%%%.example.com".replace("%%%TOKEN%%%", token); response.sendRedirect(respUrl); %> However this doesn't work. Any ideas on what I should be using instead of request, or if I'm doing anything else wrong?

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  • Add Method to Built In Class

    - by Evorlor
    I am pretty sure this is not doable, but I will go ahead and cross my fingers and ask. I am trying to add a method to a built in class. I want this method to be callable by all of the built in class's subclasses. Specifically: I have a JButton, a JTextPane, and other JComponents. I want to be able to pass in a JDom Element instead of a Rectangle to setBounds(). My current solution is to extend each JComponent subclass with the desired methods, but that is a LOT of duplicate code. Is there a way I can write the following method just one time, and have it callable on all JComponent objects? Or is it required that I extend each subclass individually, and copy and paste the method below? public void setBounds(Element element) { this.setBounds(Integer.parseInt(element.getAttribute( "x").toString()), Integer.parseInt(element .getAttribute("y").toString()), Integer .parseInt(element.getAttribute("width").toString()), Integer.parseInt(element.getAttribute("height") .toString())); }

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  • runtime/compile time polymorphism

    - by dmadhavaraj
    Hi , In the below code , why b1.subtract() fails . Please explain me the reason ie., what happens in JVM while invoking that method . class Base { public void add() { System.out.println("Base ADD"); } } class Child extends Base { public void add(){ System.out.println("Child ADD"); } public void subtract() { System.out.println("Child Subtract"); } } class MainClass { public static void main(String args[]) { Base b1 = new Base(); Base b2 = new Child(); Child b3 = new Child(); b1.add(); b1.subtract(); // ?????????** b2.add(); b3.subtract(); } }

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  • Why does "return ERROR" only work with exceptions?

    - by ThreaT
    In the struts.xml I use: <result name="error">error</result> Then in my action I use: addActionError("ERROR RETURNED"); return ERROR; When I submit the form then it just goes to a blank page and does nothing. However, if I FORCE an exception to be thrown in the action then it goes to the error page and shows the ActionError message. So am I doing this wrong? If so, how should I tell struts to show an error page using "if statements" instead of relying solely on expensive try catches? EDIT 1: I'm using struts 2 version: 2.1.8.1 EDIT 2: For example, here is my action code that I'm using to test: String test = ""; int number = 0; try { if (number == 1) { System.out.println("number 1: " + number); test = SUCCESS; } else if (number == 2) { System.out.println("number 2: " + number); addActionError("ERROR RETURNED?"); addActionMessage("TESTTEST"); test = ERROR; } else if (number == 3) { System.out.println("number 3: " + number); addActionError("ERROR RETURNED?"); addActionMessage("TESTTEST"); test = INPUT; } else { System.out.println("number 4: " + number); test = LOGIN; } } catch (Exception e) { addActionError("ERROR RETURNED? " + e); } return test; And here is my JSP code: <s:form action="number_save" method="post"> <s:textfield name="number" label="Enter number" /> </s:form> <s:actionerror /> <s:fielderror /> <s:actionmessage /> EDIT 3: Here is a longer version of my struts.xml: <action name="number" method="numberCreate" class="NumberActionBean"> <result>number.jsp</result> </action> <action name="error"> <result>error.jsp</result> </action> <action name="number_save" method="numberSave" class="NumberActionBean"> <interceptor-ref name="defaultStack"></interceptor-ref> <result name="success" type="redirect">index</result> <result name="input" type="redirect">number</result> <result name="error">error</result> <result name="login" type="redirect">login</result> <result name="none">number</result> </action> EDIT 4: My error.jsp is simply a <s:actionerror /> tag with the general taglibs and html tags...

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  • JPA atomic query/save for multithreaded app

    - by TofuBeer
    I am in the midst of changing my JPA code around to make use of threads. I have a separate entity manager and transaction for each thread. What I used to have (for the single threaded environment) was code like: // get object from the entity manager X x = getObjectX(jpaQuery); if(x == null) { x = new X(); x.setVariable(foo); entityManager.persist(x); } With that code in the multi threaded environment I am getting duplicate keys since, I assume, getObjectX returns null for a thread, then that thread is swapped out, the next thread calls getObjextX, also getting null, and then both threads will create and persist a new X(). Short of adding in synchronization, is there an atomic way to get/save-if-doesn't-exist a value with JPA or should I rethink my approach EDIT: I am using the latest Eclipselink and MySql 5.1

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  • How to debug JBoss out of memory problem?

    - by user561733
    Hello, I am trying to debug a JBoss out of memory problem. When JBoss starts up and runs for a while, it seems to use memory as intended by the startup configuration. However, it seems that when some unknown user action is taken (or the log file grows to a certain size) using the sole web application JBoss is serving up, memory increases dramatically and JBoss freezes. When JBoss freezes, it is difficult to kill the process or do anything because of low memory. When the process is finally killed via a -9 argument and the server is restarted, the log file is very small and only contains outputs from the startup of the newly started process and not any information on why the memory increased so much. This is why it is so hard to debug: server.log does not have information from the killed process. The log is set to grow to 2 GB and the log file for the new process is only about 300 Kb though it grows properly during normal memory circumstances. This is information on the JBoss configuration: JBoss (MX MicroKernel) 4.0.3 JDK 1.6.0 update 22 PermSize=512m MaxPermSize=512m Xms=1024m Xmx=6144m This is basic info on the system: Operating system: CentOS Linux 5.5 Kernel and CPU: Linux 2.6.18-194.26.1.el5 on x86_64 Processor information: Intel(R) Xeon(R) CPU E5420 @ 2.50GHz, 8 cores This is good example information on the system during normal pre-freeze conditions a few minutes after the jboss service startup: Running processes: 183 CPU load averages: 0.16 (1 min) 0.06 (5 mins) 0.09 (15 mins) CPU usage: 0% user, 0% kernel, 1% IO, 99% idle Real memory: 17.38 GB total, 2.46 GB used Virtual memory: 19.59 GB total, 0 bytes used Local disk space: 113.37 GB total, 11.89 GB used When JBoss freezes, system information looks like this: Running processes: 225 CPU load averages: 4.66 (1 min) 1.84 (5 mins) 0.93 (15 mins) CPU usage: 0% user, 12% kernel, 73% IO, 15% idle Real memory: 17.38 GB total, 17.18 GB used Virtual memory: 19.59 GB total, 706.29 MB used Local disk space: 113.37 GB total, 11.89 GB used

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  • How to send files along with parameters over http

    - by achie
    I am trying to send a zipfile from my android application to our server and I keep getting a 411 length required error. Here is the code that I am using to do that. HttpPost post = new HttpPost("http://www.xyz.org/upload.json"); post.setHeader(C.constants.HTTP_CONTENT_TYPE, "application/octet-stream"); try { FileInputStream fis = new FileInputStream("/data/data/org.myapp.appname/app_content.zip"); InputStreamEntity reqEntity = new InputStreamEntity(fis, -1); post.setEntity(reqEntity); String response = doPost(post); Log.v(tag, "response from server " + response); } catch (FileNotFoundException e) { e.printStackTrace(); } What am I doing wrong here and may I also know how I can add more parameters with this post to send them to the server.

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  • Does importing of packages change visibility of classes?

    - by Roman
    I jsut learned that A class may be declared with the modifier public, in which case that class is visible to all classes everywhere. If a class has no modifier (the default, also known as package-private), it is visible only within its own package. This is a clear statement. But this information interfere with my understanding of importing of packages (which easily can be wrong). I thought that importing a package I make classes from the imported package visible to the importing class. So, how does it work? Are public classes visible to all classes everywhere under condition that the package containing the public class is imported? Or there is not such a condition? What about the package-private classes? They are invisible no mater if the containing package was imported or not? ADDED: It seems to me that I got 2 answers which are marked as good (up-voted) and which contradict eachother.

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  • Trimmed down JAXB for just unmarshalling?

    - by fiXedd
    I'm building an application where space is at a premium. I'd really like to use JAXB's unmarshalling capabilities, but including the whole library is out of the question. Has anyone paired it down so that only the bits needed for unmarshalling are included?

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  • Delete all previous records and insert new ones

    - by carlos
    When updating an employee with id = 1 for example, what is the best way to delete all previous records in the table certificate for this employee_id and insert the new ones?. create table EMPLOYEE ( id INT NOT NULL auto_increment, first_name VARCHAR(20) default NULL, last_name VARCHAR(20) default NULL, salary INT default NULL, PRIMARY KEY (id) ); create table CERTIFICATE ( id INT NOT NULL auto_increment, certificate_name VARCHAR(30) default NULL, employee_id INT default NULL, PRIMARY KEY (id) ); Hibernate mapping <?xml version="1.0" encoding="utf-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <hibernate-mapping> <class name="Employee" table="EMPLOYEE"> <id name="id" type="int" column="id"> <generator class="sequence"> <param name="sequence">employee_seq</param> </generator> </id> <set name="certificates" lazy="false" cascade="all"> <key column="employee_id" not-null="true"/> <one-to-many class="Certificate"/> </set> <property name="firstName" column="first_name"/> <property name="lastName" column="last_name"/> <property name="salary" column="salary"/> </class> <class name="Certificate" table="CERTIFICATE"> <id name="id" type="int" column="id"> <param name="sequence">certificate_seq</param> </id> <property name="employee_id" column="employee_id" insert="false" update="false"/> <property name="name" column="certificate_name"/> </class> </hibernate-mapping>

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  • Mixing expressions and expression language (<%= %> inside of c:if)

    - by Jack
    I need to access some constants in my jsp, and sadly the EL does not offer any functionality for it. There are some options like the unstandard tag library, but I'd like to keep it a bit more standard. I tried: <%@ page import = "com.jackdane.Constants"%> <c:if test="${object.display == '<%=com.jackdane.Constants.YES %>}'"> //some display logic </c:if> But that doesn't appear to do the trick. It's been a while since I've used an expression so I might have made an error. Any input is appreciated. Edit: To clarify, the constants class is not in my control. It's inside a jar file that I recieved. It contains no getters/setters. Just private static final Strings.

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