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  • Is there programming language with better approach for switch's break statements ?

    - by Vitaly Polonetsky
    It's the same syntax in a way too many languages: switch (someValue) { case OPTION_ONE: case OPTION_LIKE_ONE: case OPTION_ONE_SIMILAR: doSomeStuff1(); break; // EXIT the switch case OPTION_TWO_WITH_PRE_ACTION: doPreActionStuff2(); // the default is to CONTINUE to next case case OPTION_TWO: doSomeStuff2(); break; // EXIT the switch case OPTION_THREE: doSomeStuff3(); break; // EXIT the switch } Now all you know that break statements are required, because the switch will continue to the next case when break statement is missing. We have an example of that with OPTION_LIKE_ONE, OPTION_ONE_SIMILAR and OPTION_TWO_WITH_PRE_ACTION. The problem is that we only need this "skip to next case" very very very rarely. And very often we put break at the end of case. It very easy for a beginner to forget about it. And one of my C teachers even explained it to us as if it was a bug in C language (don't want to talk about it :) I would like to ask if there are any other languages that I don't know of (or forgot about) that handle switch/case like this: switch (someValue) { case OPTION_ONE: continue; // CONTINUE to next case case OPTION_LIKE_ONE: continue; // CONTINUE to next case case OPTION_ONE_SIMILAR: doSomeStuff1(); // the default is to EXIT the switch case OPTION_TWO_WITH_PRE_ACTION: doPreActionStuff2(); continue; // CONTINUE to next case case OPTION_TWO: doSomeStuff2(); // the default is to EXIT the switch case OPTION_THREE: doSomeStuff3(); // the default is to EXIT the switch } The second question: is there any historical meaning to why it is like this in C? May be continue to next case was used far more often than we use it these days ?

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  • Can I have two names for the same variable?

    - by Roman
    The short version of the question: I do: x = y. Then I change x, and y is unchanged. What I want is to "bind" x and y in such a way that I change y whenever I change x. The extended version (with some details): I wrote a class ("first" class) which generates objects of another class ("second" class). In more details, every object of the second class has a name as a unique identifier. I call a static method of the first class with a name of the object from the second class. The first class checks if such an object was already generated (if it is present in the static HashMap of the first class). If it is already there, it is returned. If it is not yet there, it is created, added to the HashMap and returned. And then I have the following problem. At some stage of my program, I take an object with a specific name from the HashMap of the first class. I do something with this object (for example change values of some fields). But the object in the HashMap does not see these changes! So, in fact, I do not "take" an object from the HashMap, I "create a copy" of this object and this is what I would like to avoid.

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  • Tomcat does not persist UserPrinciple during restart

    - by mabuzer
    How to force Tomcat to serialize UserPrinciple so that the user is kept logged in when Tomcat has restarted? Right now the user has to login again everytime. Added the following lines into web-app context.xml: <Manager className="org.apache.catalina.session.PersistentManager"> <Store className="org.apache.catalina.session.FileStore"/> </Manager> but still I see login page after Tomcat restart, I use Tomcat 6.0.26

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  • JDO architecture: One to many relationship and cascading deleting

    - by user361897
    I’m new to object oriented database designs and I’m trying to understand how I should be structuring my classes in JDO for google app engine, particularly one to many relationships. Let’s say I’m building a structure for a department store where there are many departments, and each department has many products. So I’d want to have a class called Department, with a variable that is a list of a Product class. @PersistenceCapable public class Department { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) private String deptID; @Persistent private String departmentName; @Persistent private List<Product>; } @PersistenceCapable public class Product { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) private String productID; @Persistent private String productName; } But one Product can be in more than one Department (like a battery could be in electronics and household supplies). So the next question is, how do I not duplicate data in the OOD world and have only one copy of product data in numerous departments? And the next question is, let’s say I delete out a particular product, how do each of the departments know it was deleted?

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  • Changing JTextArea to JScrollPane Causes it to not be visible

    - by user1806716
    I am having an issue with JScrollPanes and JTextArea objects and getting them to work together. If I just add a JTextArea to my JPanel, it works fine and shows up where I tell it to. However, if I change the contentPane.add(textArea) to contentPane.add(new JScrollPane(textArea)), the textArea is not longer visible and there is no sign of the textarea either. Here is my code: public docToolGUI() { setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); setBounds(100, 100, 611, 487); contentPane = new JPanel(); contentPane.setBorder(new EmptyBorder(5, 5, 5, 5)); setContentPane(contentPane); contentPane.setLayout(null); textField = new JTextField(); textField.setBounds(253, 323, 86, 20); contentPane.add(textField); textField.setColumns(10); JLabel lblEnterRootDirectory = new JLabel("Enter Root Directory"); lblEnterRootDirectory.setBounds(253, 293, 127, 20); contentPane.add(lblEnterRootDirectory); JButton btnGo = new JButton("Go"); btnGo.addMouseListener(new MouseAdapter() { @Override public void mouseClicked(MouseEvent arg0) { new ToolWorker().execute(); } }); btnGo.setBounds(253, 361, 89, 23); contentPane.add(btnGo); textArea = new JTextArea(); textArea.setWrapStyleWord(true); textArea.setEditable(false); textArea.setBounds(25, 11, 560, 276); contentPane.add(new JScrollPane(textArea)); }

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  • multi-module maven project

    - by Gandalf StormCrow
    If I have 6 modules in my project is it possible to build only one out of six ? without commenting out others ? EDIT Submodule will not work itselft because or parent tags. I need to install the parent first to make it build. how can I do it without installing parent

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  • What is the correct approach to using GWT with persistent objects?

    - by dankilman
    Hi, I am currently working on a simple web application through Google App engine using GWT. It should be noted that this is my first attempt at such a task. I have run into to following problem/dilema: I have a simple Class (getters/setters and nothing more. For the sake of clarity I will refer to this Class as DataHolder) and I want to make it persistent. To do so I have used JDO which required me to add some annotations and more specifically add a Key field to be used as the primary key. The problem is that using the Key class requires me to import com.google.appengine.api.datastore.Key which is ok on the server side, but then I can't use DataHolder on the client side, because GWT doesn't allow it (as far as I know). So I have created a sister Class ClientDataHolder which is almost identical, though it doesn't have all the JDO annotations nor the Key field. Now this actually works but It feels like I'm doing something wrong. Using this approach would require maintaining to separate classes for each entity I wish to have. So my question is: Is there a better way of doing this? Thank you.

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  • Twitter rss feed 401 - unauthorisation

    - by RenegadeAndy
    Hey. I have a public twitter account and this is the rss feed for it: http://twitter.com/statuses/friends_timeline/150784631.rss The problem is, im getting an http 401 whenever im trying to access it. Can anybody explain how to stop this - and get it to work either with authentication or without! Cheers

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  • Iterate over a list and put data in hashmap

    - by sarah
    I am having a list where i need to loop over it and put its data in hashmap,i am using this approach for(int i=0;i<list.size();i++) { HashMap hMap=new HashMap(); hMap.put("Data", list); } But when i need to read the value from hMap i am doing in this way Collection c = hMap.values(); Iterator itr = c.iterator(); while(itr.hasNext()) { System.out.println("next val is--"+itr.next()); } next vali is--- is printed in com.bean.xyz@23032bc[id=1] format ,i need the exact data,how will i do this ?

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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: Prompt user to save changes when Back button is pressed

    - by chriskopec
    I have an activity that contains several user editable items (an EditText field, RatingBar, etc). I'd like to prompt the user if the back/home button is pressed and changes have been made that have not yet been saved. After reading through the android documentation, it seems like this piece of code should go in the onPause method. I've tried putting an AlertDialog in the onPause however the dialog gets shown and then immediately tears down because nothing is there to block the pause from completing. This is what I've come up with so far: @Override protected void onPause() { super.onPause(); AlertDialog ad = new AlertDialog.Builder(this).setMessage( R.string.rating_exit_message).setTitle( R.string.rating_exit_title).setCancelable(false) .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int whichButton) { // User selects OK, save changes to db } }).setNeutralButton(android.R.string.cancel, new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int whichButton) { // User selects Cancel, discard all changes } }).show(); } Am I on the right track or is there another way to accomplish what I'm trying to do here? Any help would be great!

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  • Does <T> need to be imported as a class for this to work?

    - by zxc
    In order for this to work, do you have to have an import statement for the T class? private static <T> void invertOrdering(List<T> list) { for (int i = 0; i < list.size() / 2; i++) { int j = list.size() - 1 - i; T item1 = list.get(i); T item2 = list.get(j); list.set(i, item2); list.set(j, item1); } }

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  • DATA command hangs

    - by Tharban
    Hello, what can i do, if a Mailserver accepts a connection but does not return any data? The default javax.mail implementation just hangs indefinitley. Event setting the smtp.timeout does not help - it still hangs. I even tried to set a custom SocketFactory to set the sotimeouts and solinger directly, but it still hangs. Somehow the socket does get kept alive? But how? Thx for any ideas! Ciao, Nils

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  • Selenium Webdrivers: Load Page without any resources

    - by Biffy
    I am trying to prevent Javascript from changing the site's source code I'm testing with Selenium. The problem is, I can't just simply turn Javascript off in the Webdriver, because I need it for a test. Here's what I'm doing for the Firefox Webdriver: firefoxProfile.setPreference("permissions.default.image", 2); firefoxProfile.setPreference("permissions.default.script", 2); firefoxProfile.setPreference("permissions.default.stylesheet", 2); firefoxProfile.setPreference("permissions.default.subdocument", 2); I don't allow Firefox to load any Images, Scripts and Stylesheets. How can I do this with the Internet Explorer Webdriver and the Chrome Webdriver? I have not found any similar preferences. Or is there even a more elegant way to stop the webdrivers from loading the site's JS Files after all? Thank you!

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  • Eclipse with JSR 250 (annotation) yields "Access Restriction" errors.

    - by edstafford
    Hi, Hopefully someone has come across this before. I'm running Spring STS 2.3.0 and when attempting to use the @Resource annotation from javax.annotations.Resource I get "Access restriction: The type Resource is not accessible due to restriction on required library". I'm using the JDK 6u18. I've tried changing the JDK Compliance to 1.5 and 1.6 and both yield the same error. Cheers, -Ed

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  • How do I detect the colillison of components?

    - by Coupon22
    How do I detect the collision of components, specifically JLabels (or ImageIcons?)?I have tried this: add(test1); test1.setLocation(x, y); add(test2); test1.setLocation(x1, y1); validate(); if(intersects(test1, test2)) { ehealth-=50; } public boolean intersects(JLabel testa, JLabel testb) { boolean b3 = false; if(testa.contains(testb.getX(), testb.getY())) { b3 = true; } return b3; } When I run this, it does nothing! I used to use rectangle, but it didn't go well with me. I was thinking about an image with a border (using paint.net) and moving an imageicon, but I don't know how to get the x of an imageicon or detect collision. I don't know how to detect collision of a label or increase the location either. I have searched for collision detection with components/ImageIcons, but nothing has came up. I have also searched for getting the x of ImageIcons.

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  • Do "if" statements affect in the time complexity analysis?

    - by FranXh
    According to my analysis, the running time of this algorithm should be N2, because each of the loops goes once through all the elements. I am not sure whether the presence of the if statement changes the time complexity? for(int i=0; i<N; i++){ for(int j=1; j<N; j++){ System.out.println("Yayyyy"); if(i<=j){ System.out.println("Yayyy not"); } } }

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  • switch statemt functioning improperly and giving error when i put break;

    - by nav
    The following is the code i used in a program - over here the month variable is an integer switch(month) { case 1: case 3: case 5: case 7: case 8: case 10: case 12: return 31; break; case 2: return 28; break; case 4: case 6: case 9: case 11: return 30; break; default: System.out.println("Invalid month."); return 0; } surprisingly, when i use the above switch construct.. it gives an error saying.. code unreachable for statements after each break statement Then i removed all the break statements, and the new code looks like this --- switch(month) { case 1: case 3: case 5: case 7: case 8: case 10: case 12: return 31; case 2: return 28; case 4: case 6: case 9: case 11: return 30; default: System.out.println("Invalid month."); return 0; } Now.. after removing the break statements .. the code worked perfectly well.. My question is... in the switch construct.. it is mandatory to use break.. or else the control flow continued.. and all the conditions are tested and executed!! right??? So why in the world is the previous ** syntactically Right** version giving an error.. and the modified syntactically incorrect version running perfectly well.. Any explanation.. anyone!!

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  • I have a feeling that adding fields marked with @Transient annotation to entity is very bug-prone. A

    - by Roman
    I have some philosophical feeling that adding to an entity fields which doesn't mapped to the DB is a wrong way of solving problems. But are there any concrete situations where using @Transient fields leads to implicit and hard fixing problems? For example, is it possible that adding/removing 2nd level cache will break our app when there are @Transient fields in our entities?

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  • Multiple things at once (Threads?)

    - by Jonathan
    All, What is a really simple way of having a program do more than one thing at once, even if the computer does not necessarily have multiple 'cores'. Can I do this by creating more than one Thread? My goal is to be able to have two computers networked (through Sockets) to respond to each-other's requests, while my program will at the same time be able to be managing a UI. I want the server to potentially handle more than one client at the same time as well. My understanding is that the communication is done with BufferedReader.readLine() and PrintWriter.println(). My problem is that I want the server to be waiting on multiple readLine() requests, and also be doing other things. How do I handle this? Many thanks, Jonathan

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  • FileNotFoundException when cropping a photo

    - by James G
    I'm trying to crop a photo to use in a Live Wallpaper but I'm getting a FileNotFoundException when the crop activity tries to save my new cropped image. This is the code I'm using: File file = new File(getFilesDir(), "wallpaper.jpg"); Intent intent = new Intent("com.android.camera.action.CROP"); intent.setData(uri); DisplayMetrics metrics = new DisplayMetrics(); getWindowManager().getDefaultDisplay().getMetrics(metrics); intent.putExtra("outputX", metrics.widthPixels * 2); intent.putExtra("outputY", metrics.heightPixels); intent.putExtra("aspectX", metrics.widthPixels * 2); intent.putExtra("aspectY", metrics.heightPixels); intent.putExtra("scale", true); intent.putExtra("noFaceDetection", true); intent.putExtra("output", Uri.parse("file:/" + file.getAbsolutePath())); startActivityForResult(intent, REQUEST_CROP_IMAGE); The wallpaper.jpg file seems to exist on DDMS file explorer so I'm not sure what I'm doing wrong. Any advice is greatly appreciated.

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  • Why wait should always be in synchronized block

    - by diy
    Hi gents, We all know that in order to invoke Object.wait() , this call must be placed in synchronized block,otherwise,IllegalMonitorStateException is thrown.But what's the reason for making this restriction?I know that wait() releases the monitor, but why do we need to explicitly acquire the monitor by making particular block synchronized and then release the monitor by calling wait() ? What is the potential damage if it was possible to invoke wait() outside synch block, retaining it's semantics - suspending the caller thread ? Thanks in advance

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