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  • Two entities with @ManyToOne should join the same table

    - by Ivan Yatskevich
    I have the following entities Student @Entity public class Student implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; //getter and setter for id } Teacher @Entity public class Teacher implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; //getter and setter for id } Task @Entity public class Task implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; @ManyToOne(optional = false) @JoinTable(name = "student_task", inverseJoinColumns = { @JoinColumn(name = "student_id") }) private Student author; @ManyToOne(optional = false) @JoinTable(name = "student_task", inverseJoinColumns = { @JoinColumn(name = "teacher_id") }) private Teacher curator; //getters and setters } Consider that author and curator are already stored in DB and both are in the attached state. I'm trying to persist my Task: Task task = new Task(); task.setAuthor(author); task.setCurator(curator); entityManager.persist(task); Hibernate executes the following SQL: insert into student_task (teacher_id, id) values (?, ?) which, of course, leads to null value in column "student_id" violates not-null constraint Can anyone explain this issue and possible ways to resolve it?

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  • In this example, would Customer or AccountInfo properly be the entity group parent?

    - by Badhu Seral
    In this example, the Google App Engine documentation makes the Customer the entity group parent of the AccountInfo entity. Wouldn't AccountInfo encapsulate Customer rather than the other way around? Normally I would think of an AccountInfo class as including all of the information about the Customer. import javax.jdo.annotations.IdGeneratorStrategy; import javax.jdo.annotations.PersistenceCapable; import javax.jdo.annotations.Persistent; import javax.jdo.annotations.PrimaryKey; import com.google.appengine.api.datastore.Key; import com.google.appengine.api.datastore.KeyFactory; @PersistenceCapable public class AccountInfo { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) private Key key; public void setKey(Key key) { this.key = key; } } // ... KeyFactory.Builder keyBuilder = new KeyFactory.Builder(Customer.class.getSimpleName(), "custid985135"); keyBuilder.addChild(AccountInfo.class.getSimpleName(), "acctidX142516"); Key key = keyBuilder.getKey(); AccountInfo acct = new AccountInfo(); acct.setKey(key); pm.makePersistent(acct);

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  • Tomcat Postgres Connection

    - by user191207
    Hi, I'm using a singleton class for a PostgresSQL connection inside a servelet. The problem is that once it is open it works for a while (I guess until some timeout), and then it starts throwing a I/O exception. Any idea what is happening to the singleton class inside Tomcat VM? Thanks

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  • Refreshing a JPA result list which is bound with a jTable

    - by exhuma
    First off, I hage to write this on my mobile. But I'll try to format it properly. In Netbeans I created a jTable and bound it's values to a JPA result set. This works great. The qery contains a param which i set in the pre-create box of the "query result" component. So just before netbeans creates the query result i write this: myQuery.setParameter("year", "1997"); This works fine. Now, I have an event handler which is supposed to change the param and display the new values in the table. So I do this: myQuery.setParameter("year", "2005"); myResultList.clear(); myResultList.addAll(myQuery.getResultList()); jTable1.updateUI(); This works, but it feels wrong to me. Note: the result set is bound to the table. So I was hoping there was something like this: myQuery.setParameter("year", "2005"); myResultList.refresh(); Is there something like this?

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  • Concurrent Programming:Should I write a sequential program first, then add thread safety?

    - by evthim
    I'm working on a project where we have to create a number of threads(actual number will be inputted in by testers (TA's)). I'm having trouble not only with the programming but also with the design, I can't wrap my head around all of the threads that will be invoked and where I might cause errors. The project is due soon so I don't want to waste time on this if it'll actually set me back, but I was wondering if I should write the program like only one thread will be running and everything should be sequential and then later go back and try to add the thread safety parts of the code? Would that take twice the original amount of time? Project Description: Note:I'm going to be as vague as possible so I don't violate any honor codes, sorry :( your program should accept n number of objectA threads, m number of objectB threads, and r number of objectC objectB threads interact with code in objectA. objectA threads interact with code in objectB and objectC objectB and objectC don't directly interact, but do so indirectly through objectA -ex: objectB needs something from objectA. objectA gets the result for that something by calling objectC my confusion stems mostly from the fact that all of this interactions will be done by m+n threads and there are various restrictions throughout the descriptions, like objectB can request something from objectA, and objectA has to wait for objectC to finish that something before returning it to objectB. Also each objectA thread can only work on one instruction from objectB at a time, etc. etc. I just want to know if I write the code so that there is only 1 objectA, 1 objectB and 1 object C, can I go back and easily modify it so that those 1's can be changed to m, n and r? Sorry again, if my description is a little bit confusing.

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  • How can I use BeanUtils copyProperties to copy from boolean to Boolean?

    - by carrier
    BeanUtils copyProperties, out of the box, doesn't seem to handle copying from Boolean object properties to boolean primitive properties. I figured I could create and register a converter to handle this, but that just didn't seem to work. So, how can I use BeanUtils to copy the properties from class Source to class Destination where: public class Destination { private boolean property; public boolean isProperty() { return property; } public void setProperty(boolean property) { this.property = property; } } public class Source{ private Boolean property; public Boolean getProperty() { return property; } public void setProperty(Boolean property) { this.property = property; } }

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  • How to set default values to all wrong or null parameters of method?

    - by Roman
    At the moment I have this code (and I don't like it): private RenderedImage private RenderedImage getChartImage (GanttChartModel model, String title, Integer width, Integer height, String xAxisLabel, String yAxisLabel, Boolean showLegend) { if (title == null) { title = ""; } if (xAxisLabel == null) { xAxisLabel = ""; } if (yAxisLabel == null) { yAxisLabel = ""; } if (showLegend == null) { showLegend = true; } if (width == null) { width = DEFAULT_WIDTH; } if (height == null) { height = DEFAULT_HEIGHT; } ... } How can I improve it? I have some thoughts about introducing an object which will contain all these parameters as fields and then, maybe, it'll be possible to apply builder pattern. But still don't have clear vision how to implement that and I'm not sure that it's worth to be done. Any other ideas?

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  • How to launch a web server and point the browser to it when it finishes?

    - by Wing C. Chen
    I am writing a windows batch file to do the following things: Display a picture in the middle of the screen, showing the beautiful icon of my software. Kick of the launch of the web server. Finish displaying the picture. Point the browser to the start page. I have already know how to do it in step 2 and 4. However, I have the following questions in writing the windows batch file: 1. How do I know that the launch of the web server is finished, taking jetty as the example? 2. How do I display a picture and stop displaying it when I want to? Here is what I have got so far: ::here I would like to display the picture start javaw -jar start.jar ::Starting jetty here ::here I would like to stop displaying the picture start http://localhost:8080/myApp ::Pointing the browser to the page Thank you in advance for your help.

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  • Set Caret position with JTextArea in JScrollPane

    - by Albinoswordfish
    Right now I have a JTextArea inside of a JScrollPane. For the current content it has both a vertical and horizontal scroll bar showing up. I'm trying to implement a search functionality where a user can search for a certain string and it will set the caret position to the first occurrence of that string. However it seems that JScrollPane only scrolls vertically when I set my caret position. So matching strings going off the JTextArea horizontally will completely get missed and the horizontal scroll bar won't scroll at all. I'm using the basic function setCaretPosition() for the JTextArea Does anybody have any idea why my JScrollPane isn't moving horizontally using setCaretPosition() Edit: It appears the horizontal scroll bar is scrolling but it moves so little that it's barely noticeable. I can only see the very first pixel of the character. Is there a way to have the scrollbar center (or as much as possible) to the caret position?

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  • What version of Apache HTTP Client is bundled in Android 1.6?

    - by Benju
    I want to have a seperate project that runs my server communication code in a normal JVM for the purposes of integration testing. This code uses these libraries which are build into the Android Framework... http://developer.android.com/reference/org/apache/http/client/package-summary.html Does anybody know what version of Apache HTTP Client this is supposed to be? I want to run it without the Android tests which are painfully slow.

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  • Is dependency injection only for service type objects and singletons? (and NOT for gui?)

    - by sensui
    I'm currently experimenting with the Google's guice inversion of control container. I previously had singletons for just about any service (database, active directory) my application used. Now I refactored the code: all the dependencies are given as parameters to constructors. So far, so good. Now the hardest part is with the graphical user interface. I face this problem: I have a table (JTable) of products wrapped in an ProductFrame. I give the dependencies as parameters (EditProductDialog). @Inject public ProductFrame(EditProductDialog editProductDialog) { // ... } // ... @Inject public EditProductDialog(DBProductController productController, Product product) { // ... } The problem is that guice can't know what Product I have selected in the table, so it can't know what to inject in the EditProductDialog. Dependency Injection is pretty viral (if I modify one class to use dependency injection I also need to modify all the other classes it interacts with) so my question is should I directly instantiate EditProductDialog? But then I would have to pass manually the DBProductController to the EditProductDialog and I will also need to pass it to the ProductFrame and all this boils down to not using dependency injection at all. Or is my design flawed and because of that I can't really adapt the project to dependecy injection? Give me some examples of how you used dependency injection with the graphical user interface. All the examples found on the Internet are really simple examples where you use some services (mostly databases) with dependency injection.

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  • JButton Image Ignoring GridBagConstraints

    - by daemor
    I am working on an application and have a screen that needs to have elements (namely some custom JButtons) appear and disappear based on a user selection. However for some reason, when I add these buttons to their pane, the buttton image goes to the top corner, and leaves the text in the center, completely ignoring GridBagConstraints. I am completely stumped on this one as I have done this same exact thing dozens of times earlier in the program without any issues. Here is an image of the problem: The problem is in this method here, and occurs down towards the bottom. public void init(){ contentPane.removeAll(); // Setup jlabels JLabel countyLabel = new JLabel("County"); countyLabel.setFont(new Font("Times New Roman", Font.PLAIN, 18)); JLabel measureByLabel = new JLabel("Measure By: "); measureByLabel.setFont(new Font("Times New Roman", Font.PLAIN, 18)); String[] countyChoices = {"Washtenaw", "Oakland", "Livingston"}; // setup components JComboBox<String> countyCombo = new JComboBox<String>(countyChoices); // place baseComponents c.weightx = 0.5; c.weighty = 0.5; c.gridx = 0; c.gridy = 0; c.anchor = GridBagConstraints.NORTH; contentPane.add(countyLabel, c); c.gridx = 2; contentPane.add(countyCombo, c); c.gridy = 1; c.gridx = 0; contentPane.add(trenchButton, c); c.gridx = 2; contentPane.add(bedButton, c); c.gridy = 2; c.gridx = 1; contentPane.add(systemSelection, c); c.gridy = 3; c.gridx = 0; contentPane.add(lengthButton, c); c.fill = GridBagConstraints.BOTH; c.gridwidth = 4; c.gridy = 4; c.gridx = 0; contentPane.add(choicePane, c); GridBagConstraints con = new GridBagConstraints(); con.weightx = 0.5; con.weighty = 0.5; con.gridx = 0; con.gridy = 0; choicePane.add(lengthButton, c); // revalidate and repaint choicePane.revalidate(); choicePane.repaint(); contentPane.revalidate(); contentPane.repaint(); } I have tried doing this in separate methods, the button looks fine when added to the contentPane, the pane is for sure set to gridbagconstraints as I used the expression JPanel choicePane = new JPanel(new GridBagLayout()) to initialize it.

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  • GWT: stange import collision error in visualisation api

    - by parag_
    hi, I'm attempting to add two charts to a gwt page using the visualization api, but for some strange and inexplicable reason, eclipse claims that the following two imports are colliding - which makes no sense to me. In the methods where i am calling them, I have even tried using the fully qualified names, but that doesnt seem to help either. Any idea what may be going on ? import com.google.gwt.visualization.client.visualizations.Table.Options; import com.google.gwt.visualization.client.visualizations.LineChart.Options;

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  • XML parse file from HTTP

    - by Travis
    I have an XML file located at a location such as http://example.com/test.xml I'm trying to parse the XML file to use it in my program with xPath like this but it is not working. Document doc = builder.parse(new File(url)); How can I get the XML file?

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  • Encrypt string with public key only

    - by vlahovic
    i'm currently working on a android project where i need to encrypt a string using 128 bit AES, padding PKCS7 and CBC. I don't want to use any salt for this. I've tried loads of different variations including PBEKey but i can't come up with working code. This is what i currently have: String plainText = "24124124123"; String pwd = "BobsPublicPassword"; byte[] key = pwd.getBytes(); key = cutArray(key, 16); byte[] input = plainText.getBytes(); byte[] output = null; SecretKeySpec keySpec = null; keySpec = new SecretKeySpec(key, "AES"); Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7Padding"); cipher.init(Cipher.ENCRYPT_MODE, keySpec); output = cipher.doFinal(input); private static byte[] cutArray(byte[] arr, int length){ byte[] resultArr = new byte[length]; for(int i = 0; i < length; i++ ){ resultArr[i] = arr[i]; } return resultArr; } Any help appreciated //Vlahovic

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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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  • Calculated group-by fields in MongoDB

    - by Navin Viswanath
    For this example from the MongoDB documentation, how do I write the query using MongoTemplate? db.sales.aggregate( [ { $group : { _id : { month: { $month: "$date" }, day: { $dayOfMonth: "$date" }, year: { $year: "$date" } }, totalPrice: { $sum: { $multiply: [ "$price", "$quantity" ] } }, averageQuantity: { $avg: "$quantity" }, count: { $sum: 1 } } } ] ) Or in general, how do I group by a calculated field?

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  • Embedding XSL Stylesheet into XML

    - by user700996
    I have the following XML: <?xml version="1.0" encoding="ISO-8859-1"?> <?xml-stylesheet type="text/xsl" href="http://www.fakedomain.com/sally.xsl"?> And the following content in sally.xsl: <?xml version="1.0" encoding="ISO-8859-1"?> <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> <xsl:template match="/"> <html> <body> <xsl:for-each select="documentcollection/document"> <p> <xsl:for-each select="rss/channel/item"> <xsl:value-of select="title"/><br /> <xsl:value-of select="description"/><br /> <xsl:value-of select="link"/><br /> </xsl:for-each> </p> </xsl:for-each> </body> </html> </xsl:template> </xsl:stylesheet> However, the browser displays the XML as though the XSL line is not present. Do you know why the browser is ignoring the XSL stylesheet? Is the style sheet wrong? Thanks

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