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  • JPA entity design / cannot delete entity

    - by timaschew
    I though its simple what I want, but I cannot find any solution for my problem. I'm using playframework 1.2.3 and it's using Hibernate as JPA. So I think playframework has nothing to do with the problem. I have some classes (I omit the nonrelevant fields) public class User { ... } public class Task { public DataContainer dataContainer; } public class DataContainer { public Session session; public User user; } public class Session { ... } So I have association from Task to DataContainer and from DataContainer to Sesssion and the DataContainer belongs to a User. The DataContainers can have always the same User, but the Session have to be different for each instance. And the DataContainer of a Task have also to be different in each instance. A DataContainer can have a Sesesion or not (it's optinal). I use only unidirectional assoc. It should be sufficient. In other words: Every Task must has one DataContainer. Every DataContainer must has one/the same User and can have one Session. To create a DB schema I use JPA annotations: @Entity public class User extends Model { ... } @Entity public class Task extends Model { @OneToOne(optional = false, cascade = CascadeType.ALL) public DataContainer dataContainer; } @Entity public class DataContainer extends Model { @OneToOne(optional = true, cascade = CascadeType.ALL) public Session session; @ManyToOne(optional = false, cascade = CascadeType.ALL) public User user; } @Entity public class Session extends Model { ... } BTW: Model is a play class and provides the primary id as long type. When I create some for each entity a object and 'connect them', I mean the associations, it works fine. But when I try to delete a Session, I get a constraint violation exception, because a DataContainer still refers to the Session I want to delete. I want that the Session (field) of the DataContainer will be set to null respectively the foreign key (session_id) should be unset in the database. This will be okay, because its optional. I don't know, I think I have multiple problems. Am I using the right annotation @OneToOne ? I found on the internet some additional annotation and attributes: @JoinColumn and a mappedBy attribute for the inverse relationship. But I don't have it, because its not bidirectional. Or is a bidirectional assoc. essentially? Another try was to use @OnDelete(action = OnDeleteAction.CASCADE) the the contraint changed from NO ACTIONs when update or delete to: ADD CONSTRAINT fk4745c17e6a46a56 FOREIGN KEY (session_id) REFERENCES annotation_session (id) MATCH SIMPLE ON UPDATE NO ACTION ON DELETE CASCADE; But in this case, when I delete a session, the DataContainer and User is deleted. That's wrong for me. EDIT: I'm using postgresql 9, the jdbc stuff is included in play, my only db config is db=postgres://app:app@localhost:5432/app

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  • Licensing Android Apache Commons Math

    - by stefple
    I am about to release my first commercial software ever. I didnt study something related to programming so i am facing a problem here, which is licensing. I am not native english speaking, so i have a little bit of a problem when i read the Apache Commons License. In my software i use the Apache Commons Math library. If i understand their FAQ i just may distribute my software if i add this (the text will come up at my "info" screen inside the app): [...] \nCopyright 2012 xxxstefplexxxx \n\n This software uses Apache Commons Math Library \nThe license can be found here: \nhttp://www.apache.org/licenses/LICENSE-2.0 \n

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  • andromda problem

    - by clark
    hi, I work now with andromda generator,and where I try to generate code ,I have this problem : "The default goals should be specified in the section of project.xml instead of maven.xml ". I use maven1.1 to download andromda plug-in

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  • Help naming a class that has a single public method called Execute()

    - by devoured elysium
    I have designed the following class that should work kind of like a method (usually the user will just run Execute()): public abstract class ??? { protected bool hasFailed = false; protected bool hasRun = false; public bool HasFailed { get { return hasFailed; } } public bool HasRun { get { return hasRun; } } private void Restart() { hasFailed = false; hasRun = false; } public bool Execute() { ExecuteImplementation(); bool returnValue = hasFailed; Restart(); return returnValue; } protected abstract void ExecuteImplementation(); } My question is: how should I name this class? Runnable? Method(sounds awkward)?

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  • Android ListActivity with Bitmaps and Garbage Collection issue

    - by chis54
    I have a ListActivity and in it I set my list items with a class that extends SimpleCursorAdapter. I'm overriding bindView to set my Views. I have some TextViews and ImageViews. This is how I set my list items in my cursor adapter: String variableName = "drawable/q" + num + "_200px"; int imageResource = context.getResources().getIdentifier(variableName, "drawable", context.getPackageName()); if (imageResource != 0 ) { // The drawable exists Bitmap b = BitmapFactory.decodeResource(context.getResources(), imageResource); width = b.getWidth(); height = b.getHeight(); imageView.getLayoutParams().width = (int) (width); imageView.getLayoutParams().height = (int) (height); imageView.setImageResource(imageResource); } else { imageView.setImageResource(R.drawable.25trans_200px); } The problem I'm having is whenever I update my list with setListAdapter I get a large amount of garbage collection: D/dalvikvm(18637): GC_EXTERNAL_ALLOC freed 125K, 51% free 2710K/5447K, external 2022K/2137K, paused 75ms D/dalvikvm(18637): GC_EXTERNAL_ALLOC freed 30K, 51% free 2701K/5447K, external 2669K/2972K, paused 64ms D/dalvikvm(18637): GC_EXTERNAL_ALLOC freed 23K, 51% free 2713K/5447K, external 3479K/3579K, paused 53ms D/dalvikvm(18637): GC_EXTERNAL_ALLOC freed 22K, 51% free 2706K/5447K, external 3303K/3352K, paused 64ms D/dalvikvm(18637): GC_EXTERNAL_ALLOC freed 21K, 51% free 2722K/5447K, external 3569K/3685K, paused 102ms D/dalvikvm(18637): GC_EXTERNAL_ALLOC freed 23K, 50% free 2755K/5447K, external 3499K/3605K, paused 65ms D/dalvikvm(18637): GC_EXTERNAL_ALLOC freed 23K, 50% free 2771K/5447K, external 4213K/4488K, paused 53ms D/dalvikvm(18637): GC_EXTERNAL_ALLOC freed 18K, 49% free 2796K/5447K, external 5057K/5343K, paused 75ms D/dalvikvm(18637): GC_EXTERNAL_ALLOC freed 28K, 49% free 2803K/5447K, external 5944K/5976K, paused 53ms D/dalvikvm( 435): GC_EXPLICIT freed 6K, 54% free 2544K/5511K, external 1625K/2137K, paused 50ms D/dalvikvm( 165): GC_EXPLICIT freed 85K, 52% free 2946K/6087K, external 4838K/5980K, paused 111ms D/dalvikvm( 448): GC_EXPLICIT freed 1K, 54% free 2540K/5511K, external 1625K/2137K, paused 50ms D/dalvikvm( 294): GC_EXPLICIT freed 8K, 55% free 2598K/5703K, external 1625K/2137K, paused 64ms What can I do to avoid this? It's causing my UI to be sluggish and when I scroll, too.

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  • Migrating from hand-written persistence layer to ORM

    - by Sergey Mikhanov
    Hi community, We are currently evaluating options for migrating from hand-written persistence layer to ORM. We have a bunch of legacy persistent objects (~200), that implement simple interface like this: interface JDBC { public long getId(); public void setId(long id); public void retrieve(); public void setDataSource(DataSource ds); } When retrieve() is called, object populates itself by issuing handwritten SQL queries to the connection provided using the ID it received in the setter (this usually is the only parameter to the query). It manages its statements, result sets, etc itself. Some of the objects have special flavors of retrive() method, like retrieveByName(), in this case a different SQL is issued. Queries could be quite complex, we often join several tables to populate the sets representing relations to other objects, sometimes join queries are issued on-demand in the specific getter (lazy loading). So basically, we have implemented most of the ORM's functionality manually. The reason for that was performance. We have very strong requirements for speed, and back in 2005 (when this code was written) performance tests has shown that none of mainstream ORMs were that fast as hand-written SQL. The problems we are facing now that make us think of ORM are: Most of the paths in this code are well-tested and are stable. However, some rarely-used code is prone to result set and connection leaks that are very hard to detect We are currently squeezing some additional performance by adding caching to our persistence layer and it's a huge pain to maintain the cached objects manually in this setup Support of this code when DB schema changes is a big problem. I am looking for an advice on what could be the best alternative for us. As far as I know, ORMs has advanced in last 5 years, so it might be that now there's one that offers an acceptable performance. As I see this issue, we need to address those points: Find some way to reuse at least some of the written SQL to express mappings Have the possibility to issue native SQL queries without the necessity to manually decompose their results (i.e. avoid manual rs.getInt(42) as they are very sensitive to schema changes) Add a non-intrusive caching layer Keep the performance figures. Is there any ORM framework you could recommend with regards to that?

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  • Loading data in constructors and not in constructors

    - by Richeve S. Bebedor
    I just want to know the difference between loading the data inside the constructor and loading the data outside the constructor but not inside any methods example: Loading inside constructor public class Model{ Object testobject; public Model(){ testobject=new Object(); } } VS example: Loading outside constructor public class Model{ Object testobject=new Object(); public Model(){ } }

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  • Return type value if RunTimeException has been thrown and not catched.

    - by Alfred
    I am using Gson to parse Json. What I don't understand what the return type will be if you don't catch the Runtime Exception. I was expecting it to be null, but it is not null when evaluating with a simple if statement. My code looks something like this: public X x() { return gson.fromJson(jsonString, X.class); } then from another function I call the function: public void y() { final X x = x(); if (x == null) { System.out.println("x == null") } } I was expecting x to be null, but it isn't because the print statement is not called? What is the value of x? How can if them. I have my problem by using a catch block in the x() function and returning null. But I am just wondering what the value of function x() is(if any?)? Hopefully I make any sense at all.

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  • How to remove duplicate line in a file

    - by Abs
    Hi I'm using the below method to write to a file from the Jtextarea and I call this method every 30 second within a Timer but instead to add only new line in file it rewrite the entire lines contained in Jtextarea so then I have duplicate lines. I want to avoid this and update the file just with new lines. Could you help me please. public void loger() { FileWriter writer = null; try { writer = new FileWriter("MBM_Log_"+date()+".txt" , true); textArea.write(writer); } catch (IOException exception) { System.err.println("log error"); exception.printStackTrace(); } finally { if (writer != null) { try { writer.close(); } catch (IOException exception) { System.err.println("Error closing writer"); exception.printStackTrace(); } } } }

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  • oracle connectivity

    - by jayprakash
    String serverName = "127.0.0.1"; String portNumber = "1521"; String sid = "database"; String url = "jdbc:oracle:thin:@" + serverName + ":" + portNumber + ":" + sid; String username = "scott"; String password = "tiger"; connection = DriverManager.getConnection(url, username, password); Could not connect to the database

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  • How to bring up list of available notification sounds on Android

    - by robintw
    I'm creating notifications in my Android application, and would like to have an option in my preferences to set what sound is used for the notification. I know that in the Settings application you can choose a default notification sound from a list. Where does that list come from, and is there a way for me to display the same list in my application?

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  • Calcualting Optimal Site to Site Routing using pre-computed times between sites

    - by Idistic
    Assume that I have a number of sites (locations) and the time it takes to travel from each site to each site is pre-computed Example Data - Site to Site Pre-Calculated Times in minutes From Start Site To A 20 To B 15 To C 15 From Site A To B 10 To C 15 Site B To A 10 To C 20 Site C To A 15 To B 20 4 Sites is fairly simple, but what if the site set was say 1000 sites? Given a large site set What would the best approach be to quickly find the optimal routes from the start site while visiting every other site just once? Route Solutions from Start Site for 3 sites from a start site 1 A(20) B(10) C(20) = 50 2 A(20) C(15) B(20) = 55 3 B(15) A(10) C(15) = 40 4 B(15) C(20) A(15) = 50 5 C(15) A(15) B(10) = 40 6 C(15) B(20) A(10) = 45

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  • How can I load a property lazily in JDO (on Google App Engine)?

    - by luciano
    I have this code in one of my @PersistenceCapable classes: @Persistent private Blob data; The Blob can be quite big, so I'd like to load it lazily since most of the times I don't need it. How can I annotate that property to avoid immediate loading? I could create another class that contains the Blob alone and then use a lazy one-to-one, but I'd like to solve this with annotations.

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  • How do I remove implementing types from GWT’s Serialization Policy?

    - by Bluu
    The opposite of this question: http://stackoverflow.com/questions/138099/how-do-i-add-a-type-to-gwts-serialization-policy-whitelist GWT is adding undesired types to the serialization policy and bloating my JS. How do I trim my GWT whitelist by hand? Or should I at all? For example, if I put the interface List on a GWT RPC service class, GWT has to generate Javascript that handles ArrayList, LinkedList, Stack, Vector, ... even though my team knows we're only ever going to return an ArrayList. I could just make the method's return type ArrayList, but I like relying on an interface rather than a specific implementation. After all, maybe one day we will switch it up and return e.g. a LinkedList. In that case, I'd like to force the GWT serialization policy to compile for only ArrayList and LinkedList. No Stacks or Vectors. These implicit restrictions have one huge downside I can think of: a new member of the team starts returning Vectors, which will be a runtime error. So besides the question in the title, what is your experience designing around this?

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  • Handling multiple exceptions

    - by the-banana-king
    Hi there, I have written a class which loads configuration objects of my application and keeps track of them so that I can easily write out changes or reload the whole configuration at once with a single method call. However, each configuration object might potentially throw an exception when doing IO, yet I do not want those errors to cancel the overall process so that the other objects are still given a chance to reload/write. Therefore I collect all exceptions which are thrown while iterating over the objects and store them in a super-exception, which is thrown after the loop, since each exception must still be handled and someone has to be notified of what exactly went wrong. However, that approach looks a bit odd to me. Someone out there with a cleaner solution? Here is some code of the mentioned class: public synchronized void store() throws MultipleCauseException { MultipleCauseException me = new MultipleCauseException("unable to store some resources"); for(Resource resource : this.resources.values()) { try { resource.store(); } catch(StoreException e) { me.addCause(e); } } if(me.hasCauses()) throw me; }

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  • how to call service inside service layer

    - by cometta
    in my service layer public class MyServiceLayerImpl{ @Autowired MyServiceInterface MyServiceLayer } if i have method inside service layer that need to call another service inside service layer. i cannot use this._method ,because, i'm using AOP for caching. In order for the caching to work, i have to use @Autowired to get the service. Therefore, is the above style ok?

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  • When combo box is selected then display Combo Box and then when any Item in Combo Box is selected then make JTextField visible

    - by Gugz_Singh
    I am having trouble with my code. What i'm trying to do is: 1. Create a Check Box, make it visible 2. When Check Box is selected display Combo Box, which will have few items for example ("1","2") 3. When 1 is selected from Combo Box then make 1 Text Field visible 4. When 2 is selected from Combo Box then make 2 Text Field's visible What I am able to do is when Check Box is clicked, it displays the Combo Box with the items. I am not able provide functionality to the items in the Combo Box, such as when Item1 is clicked then make 1 Text Field visible. Please help needed. My Code: public void replacement_used(){ no_of_part_used_label.setVisible(false); no_part_used_list.setVisible(false); part_no_one_label.setVisible(false); part_no_one_field.setVisible(false); part_no_two_label.setVisible(false); part_no_two_field.setVisible(false); part_no_three_label.setVisible(false); part_no_three_field.setVisible(false); part_no_four_label.setVisible(false); part_no_four_field.setVisible(false); part_no_five_label.setVisible(false); part_no_five_field.setVisible(false); HandlerClass handler = new HandlerClass(); replacement_part_check_box.addItemListener(handler); } private class HandlerClass implements ItemListener{ public void itemStateChanged(ItemEvent event){ if (replacement_part_check_box.isSelected()){ no_of_part_used_label.setVisible(true); no_part_used_list.setVisible(true); } x(); } } public void x(){ System.out.println("Start of x fucntion"); if( no_part_used_list.getSelectedItem().equals("1") ){ System.out.println("It is 1"); part_no_one_label.setVisible(true); part_no_one_field.setVisible(true); } }

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  • auto resize content of label

    - by user161004
    i have got a label in my program which displays a image. The problem id if an image is selected which is greater than the size of the label,only some part of the image is displayed while others are not displayed. What should i do so that the enire image is displayed???

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