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  • How to have a run in an Service?

    - by user1497664
    I have implemented an service that runs in a seperate process. This service contains a separate thread where i have a socket connection. This thread has a run() where it is continuously sending data to the port. My problem is after triggering the run() in the thread i don't get any contact with it anymore, i can see in the program that have open the socket that it consciously sends the data but the idea was that i while it is running i could change data that it sends for an example time. here is my run in the external thread: public void run() { if(run) { // Team and player names message is sent when entering in a game setBaseMessage(); SendMessageToCOMPort(base_message + CalculateCRC(base_message)); sleep(); // waits for 100 ms } } Anyone have any idea what might be wrong ?

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  • Exception handling pattern

    - by treefrog
    It is a common pattern I see where the error codes associated with an exception are stored as Static final ints. when the exception is created to be thrown, it is constructed with one of these codes along with an error message. This results in the method that is going to catch it having to look at the code and then decide on a course of action. The alternative seems to be- declare a class for EVERY exception error case Is there a middle ground ? what is the recommended method ?

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  • JFileChooser select directory but show files

    - by Jeff Storey
    I feel like there should be a simple way to do this but I can't figure it out. I have a JFileChooser that allows the user to select directories. I want to show all the files in the directories to give the user some context, but only directories should be accepted as selections (maybe the Open button would be disabled when a file is selected). Is there an easy way of doing this?

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  • Creating Pages with unique PageMaps

    - by Michael Krauklis
    I have a wicket Application that has long lived Pages. I would like each instance of this Page to be created with a unique PageMap for reasons I won't get into here, but when I try to specify a PageMap on the constructor of my Page I end up getting OOM and StackOverflow errors. Here is the code: public <CTOR>() { super(Session.get().newPageMap("" + System.currentTimeMillis())); ... I'm using a custom BookmarkablePageLink (custom in that it does not pass on the current PageMap name to the new Page) to effectively abandon the old Page/PageMap and create a new one with a new PageMap. The errors seem to be coming from page serialization after only two or three pages have been created. Can anyone find issue with this approach?

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  • Best practice when removing entity regarding mappedBy collections?

    - by Daniel Bleisteiner
    I'm still kind of undecided which is the best practice to handle em.remove(entity) with this entity being in several collections mapped using mappedBy in JPA. Consider an entity like a Property that references three other entities: a Descriptor, a BusinessObject and a Level entity. The mapping is defined using @ManyToOne in the Property entity and using @OneToMany(mappedBy...) in the other three objects. That inverse mapping is defined because there are some situations where I need to access those collections. Whenever I remove a Property using em.remove(prop) this element is not automatically removed from managed entities of the other three types. If I don't care about that and the following page load (webapp) doesn't reload those entities the Property is still found and some decisions might be taken that are no longer true. The inverse mappings may become quite large and though I don't want to use something like descriptor.getProperties().remove(prop) because it will load all those properties that might have been lazy loaded until then. So my currently preferred way is to refresh the entity if it is managed: if (em.contains(descriptor)) em.refresh(descriptor) - which unloads a possibly loaded collection and triggers a reload upon the next access. Is there another feasible way to handle all those mappedBy collections of already loaded entites?

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  • Backing Bean not getting values sent by javascript

    - by Developer106
    I have three drop down lists whose values are been copied to <h:inputHidden> components by the following JavaScript function: function getBirthDate() { var months = document.getElementById("months") var hidden1 = document.getElementById("formsignup:monthField"); hidden1.value = months.options[months.selectedIndex].text; var days = document.getElementById("days"); var hidden2 = document.getElementById("formsignup:dayField"); hidden2.value = days.options[days.selectedIndex].value; var years = document.getElementById("years"); var hidden3 = document.getElementById("formsignup:yearField"); hidden3.value = years.options[years.selectedIndex].value; } Here are the three <h:inputHidden> components: <h:inputHidden value="#{signupBean.month}" id="monthField"/> <h:inputHidden value="#{signupBean.day}" id="dayField"/> <h:inputHidden value="#{signupBean.year}" id="yearField"/> This is the command button that is supposed to invoke the function that copies the values to the inputs and then submits them to the backing bean. <h:commandButton image="images/images/signup1.png" styleClass="joinnow" id="joinus" action="#{signupBean.save}" onclick="getBirthDate()" /> But they arrive as null in the backing bean. How is this caused and how can I solve it?

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  • Null Pointer Exception

    - by user1507835
    I am getting a null pointer exception, but I dont know why. I checked to see if the cell was null before I read it to a string. So, why is that string null? private void fillArray() private void fillArray() { try { readBook = new HSSFWorkbook(readFile); } catch (IOException e) { System.out .println("If we know what we're doing, no one should ever see this line."); } if (readBook != null) {HSSFSheet infoSheet = readBook.getSheetAt(0); HSSFRow headingsRow = infoSheet.getRow(0); int i = 0; HSSFCell cell = headingsRow.getCell(i); String columnHeading = cell.toString(); while (cell != null && !(cell.toString().equals(""))) { cell = headingsRow.getCell(i); columnHeading = cell.toString(); columnHeadings.add(columnHeading); i++; } if(columnListIsSetup == false) { createList(); columnListIsSetup = true; } }

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  • Synchronize JTextFields Values by PropertyChangeListener

    - by gt_ebuddy
    I want to copy the value of a jTextField - TXTFLD1 to another jTextField -TXTFLD2 when the value at TXTFLD1 changes. I choose propertychangelistener because i cannot detect when the value at TXTFLD1 is changed, Because it is changed by some external code which i cannot modify now. The test code is as follows : public class TxtFldSync extends JFrame { private JButton BTN1 = null; private JTextField TXTFLD1 = null; private JTextField TXTFLD2 = null; public static void main(String[] args) { TxtFldSync thisClass = new TxtFldSync(); thisClass.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); thisClass.setVisible(true); } public TxtFldSync() { super(); this.setSize(300, 200); BTN1 = new JButton(); BTN1.setBounds(new Rectangle(178, 38, 67, 17)); TXTFLD1 = new JTextField(); TXTFLD1.setBounds(new Rectangle(32, 42, 83, 20)); TXTFLD2 = new JTextField(); TXTFLD2.setBounds(new Rectangle(30, 78, 83, 20)); //listeners TXTFLD1.addPropertyChangeListener("value", new PropertyChangeListener() { @Override public void propertyChange(PropertyChangeEvent arg0) { TXTFLD2.setText(TXTFLD1.getText()+"set by change listener"); //this doesnot work why ? } }); BTN1.addActionListener( new ActionListener() { @Override public void actionPerformed(ActionEvent arg0) { TXTFLD1.setText("Action Performed"); //i what to set same value to TXTFLD2 using property change listener } }); this.setContentPane(new Container()); this.getContentPane().add(BTN1); this.getContentPane().add(TXTFLD1); this.getContentPane().add(TXTFLD2); } } Why the property change listener is not working. What are the other alternatives solution for this problem?

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  • Abstract class get parameter from implementing subclass?

    - by soren.qvist
    I'm wondering if there is way to do this without breaking encapsulation, I want the abstract class to rely on parameters defined in the implementing subclass. Like so: public abstract class Parent { private int size; private List<String> someList; public Parent() { size = getSize(); someList = new ArrayList<String>(size); } public abstract int getSize(); } public class Child extends Parent { @Override public int getSize() { return 5; } } Is this ugly? Is there a better way? And perhaps more importantly, is this even a good idea?

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  • Scrolling down an awt.List

    - by nico
    As from subject, I have an awt.List object. When I add something to the list I would like to scroll it down to show the last inserted object. For instance: myList.add("sometext"); myList.select(myList.getItemCount()-1); myList.showSelectedItem(); // Or something like that The documentation does not seem to list any method that does something like that, can anybody help please?

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  • ServiceLoader double iterator issues

    - by buge
    Is this a known issue? I had trouble finding any search results. When iterating over a ServiceLoader while an iteration already is in progress, the first iteration will be aborted. For example, assuming there are at least two implementations of Foo, the following code will fail with an AssertionError: ServiceLoader<Foo> loader = ServiceLoader.load(Foo.class); Iterator<Foo> iter1 = loader.iterator(); iter1.next(); Iterator<Foo> iter2 = loader.iterator(); while (iter2.hasNext()) { iter2.next(); } assert iter1.hasNext(); This only seems to occur, if the second iterator really terminates. The code will succeed in this variation for example: ServiceLoader<Foo> loader = ServiceLoader.load(Foo.class); Iterator<Foo> iter1 = loader.iterator(); iter1.next(); Iterator<Foo> iter2 = loader.iterator(); iter2.next(); assert iter1.hasNext(); Is this a bug or a feature? :p Is there a ticket for this already anywhere?

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  • does anyone see any issues with this thread pattern?

    - by prmatta
    Here is a simple thread pattern that I use when writing a class that needs just one thread, and needs to a specific task. The usual requirements for such a class are that it should be startable, stopable and restartable. Does anyone see any issues with this pattern that I use? public class MyThread implements Runnable { private boolean _exit = false; private Thread _thread = null; public void start () { if (_thread == null) { _thread = new Thread(this, "MyThread"); _thread.start(); } } public void run () { while (_exit) { //do something } } public void stop () { _exit = true; if (_thread != null) { _thread.interrupt(); _thread = null; } } } I am looking for comments around if I am missing something, or if there is a better way to write this.

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  • Creating an instance within the Class itself

    - by didxga
    What's going on when the assignment statement executed at Line 4, does compiler ignore the new operator and keep the foo variable being null or something else happen to handle this awkward moment? public class Foo { // creating an instance before its constructor has been invoked, suppose the "initializing" // gets printed in constructor as a result of the next line, of course it will not print it private Foo foo = new Foo();//Line 4 public Foo() { System.out.println("initializing"); } }

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  • public (static) swap() method vs. redundant (non-static) private ones...

    - by Helper Method
    I'm revisiting data structures and algorithms to refresh my knowledge and from time to time I stumble across this problem: Often, several data structures do need to swap some elements on the underlying array. So I implement the swap() method in ADT1, ADT2 as a private non-static method. The good thing is, being a private method I don't need to check on the parameters, the bad thing is redundancy. But if I put the swap() method in a helper class as a public static method, I need to check the indices every time for validity, making the swap call very unefficient when many swaps are done. So what should I do? Neglect the performance degragation, or write small but redundant code?

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  • Can a plain servlet be configured to as a seam component?

    - by stacker
    I created a plain servlet within a seam-gen (2.1.2) application, now I would like to use injection. Thus I annotated it with @Name and it's recognized as component: INFO [Component] Component: ConfigReport, scope: EVENT, type: JAVA_BEAN, class: com.mycompany.servlet.ConfigReport Unfortunatly the injection of the logger doesn't work NullPointerException in init() import org.jboss.seam.annotations.Logger; import org.jboss.seam.annotations.Name; import org.jboss.seam.log.Log; @Name("ConfigReport") public class ConfigReport extends HttpServlet { @Logger private Log log; public void init(ServletConfig config) throws ServletException { log.info( "BOOM" ); } } Is my approach abusive? What would be the alternatives (the client sending requests to the servlet is curl, not a browser)?

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  • How do I check that an entity is unreferenced in JPA?

    - by Martin
    I have the following model @Entity class Element { @Id int id; @Version int version; @ManyToOne Type type; } @Entity class Type { @Id int id; @Version int version; @OneToMany(mappedBy="type") Collection<Element> elements; @Basic(optional=false) boolean disabled; } and would like to allow Type.disabled = true only if Type.elements is empty. Is there a way to do it atomically? I would like to prevent an insertion of an Element in a transaction while the corresponding Type is being disabled by an other transaction.

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  • disable the Home Button and Back Button"

    - by michael
    i want way to disable the Home Button & Back Button when click on checkbox in application , my application on version 4.2.2 i have code but not work when click on checkbox work stop to application public void HardButtonOnClick(View v) { boolean checked1 = ((CheckBox) v).isChecked(); if(checked1) { SQLiteDatabase db; db = openOrCreateDatabase("Saftey.db", SQLiteDatabase.CREATE_IF_NECESSARY, null); db.setVersion(1); db.setLocale(Locale.getDefault()); db.setLockingEnabled(true); ContentValues values = new ContentValues(); values.put("hardBtn", "YES"); db.update("Setting", values, "id = ?", new String[] { "1" }); Toast.makeText(this, "Hard Button Locked", Toast.LENGTH_LONG).show(); //SharedPreferences pref = getSharedPreferences("pref",0); //SharedPreferences.Editor edit = pref.edit(); //edit.putString("hard","yes"); //edit.commit(); /* String Lock="yes" ; Bundle bundle = new Bundle(); bundle.putString("key", Lock); Intent a = new Intent(Change_setting.this, ChildMode.class); a.putExtras(bundle); startActivity(a);*/ super.onAttachedToWindow(); this.getWindow().setType(WindowManager.LayoutParams.TYPE_KEYGUARD); isLock = true; } else { SQLiteDatabase db; db = openOrCreateDatabase("Saftey.db", SQLiteDatabase.CREATE_IF_NECESSARY, null); db.setVersion(1); db.setLocale(Locale.getDefault()); db.setLockingEnabled(true); ContentValues values = new ContentValues(); values.put("hardBtn", "NO"); db.update("Setting", values, "id = ?", new String[] { "1" }); //SharedPreferences pref = getSharedPreferences("pref",0); //SharedPreferences.Editor edit = pref.edit(); //edit.putString("hard","no"); //edit.commit(); Toast.makeText(this, "Hard Button Un-Locked", Toast.LENGTH_LONG).show(); isLock = false; } } how can work it??

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  • Php security question

    - by Camran
    I have a linux server, and I am about to upload a classifieds website to it. The website is php based. That means php code adds/removes classifieds, with the help of the users offcourse. The php-code then adds/removes a classified to a database index called Solr (like MySql). Problem is that anybody can currently access the database, but I only want the website to access the database (solr). Solr is on port 8983 as standard btw. My Q is, if I add a rule in my firewall (iptables), to only allow connections coming from the servers IP to the Solr port nr, would this solve my issue? Thanks

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  • Will this be garbage collected in JVM?

    - by stjowa
    I am running the following code every two minutes via a Timer: object = new Object(this); Potentially, this is a lot of objects being created and a lot of objects being overwritten. Do the overwritten objects get garbage collected, even with a reference to itself being used in the newly created object? I am using JDK 1.6.0_13. Thanks for the help.

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  • Finding the specific type held in an ArrayList<Object> (ie. Object = String, etc.)

    - by Christopher Griffith
    Say I have an ArrayList that I have cast to an ArrayList of objects. I know that all the objects that were in the ArrayList I cast were of the same type, but not what the type was. Now, if the ArrayList is not empty, I could take one of the objects in it and use the instanceof operator to learn what the actual type is. But what of the case where the ArrayList is empty? How do I determine what type Object actually is then? Is it possible?

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  • program to determine number of duplicates in a sentence

    - by bhavna raghuvanshi
    public class duplicate { public static void main(String[] args)throws IOException { System.out.println("Enter words separated by spaces ('.' to quit):"); Set<String> s = new HashSet<String>(); Scanner input = new Scanner(System.in); while (true) { String token = input.next(); if (".".equals(token)) break; if (!s.add(token)) System.out.println("Duplicate detected: " + token); } System.out.println(s.size() + " distinct words:\n" + s); } } my program detects and prints duplicate words but i need to print the number of duplicate words also. pls help me do it.

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