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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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  • Annotations: methods vs variables

    - by Zenzen
    I was always sure (don't know why) that it's better to add annotations to variables, but while browsing the Hibernate doc http://docs.jboss.org/hibernate/stable/annotations/reference/en/html_single/#entity-hibspec-collection I noticed they tend to annotate the methods. So should I put my annotations before methods, like this: @Entity public class Flight implements Serializable { private long id; @Id @GeneratedValue public long getId() { return id; } public void setId(long id) { this.id = id; } } Or is it better to do it like this: @Entity public class Flight implements Serializable { @Id @GeneratedValue private long id; public long getId() { return id; } public void setId(long id) { this.id = id; } } Or maybe there's no difference?

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  • Create automatically only getters in Eclipse

    - by lerad
    In Eclipse is it possible to create automatically Getters and Setters for a field. But I have a lot of private fields for which only getters should exist. Is somewhere in Eclipse a "create Getters" Function which does not create setters too? Well, it is not so much work to write getters, but doing it automatically would be nice :) Thank you, lerad

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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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  • Making a FTP connection in Android

    - by Elisha Khan
    i am working to make a Android application that can upload and download data from android phone to server using this link. As i am new to connection Android with server. is my local host works as a server to download and upload. i am using Uri ftpUri = Uri.parse("ftp://10.0.2.2"); But its not working help me to get out of this problem. I need your help just to sucessfullt connect to server, As i already said i aam new to connect Android Application to server. I am learning Programing myself and Internet is my teacher. Thank You Very Much

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  • What happens if an exception is thrown in finalize()

    - by Psykocyber
    What would happen if an exception is thrown during the execution of finalize()? Is the stack unwind like normally? Does it continue finalize() and ignore the exception? Does it stop finalize() and continue GC the object? Or something else? I'm not looking for guidelines of using finalize() there are plently of pages explaining that.

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  • Can I write a test without any assert in it ?

    - by stratwine
    Hi, I'd like to know if it is "ok" to write a test without any "assert" in it. So the test would fail only when an exception / error has occured. Eg: like a test which has a simple select query, to ensure that the database configuration is right. So when I change some db-configuration, I re-run this test and check if the configuration is right. ? Thanks!

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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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  • 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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  • 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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  • password is auto-completed despite setting redisplay=false in JSP (Struts)

    - by lmcgowin
    So I have a web application on Tomcat, built on top of Struts 1.1. Here is a snippet of my JSP, it's a login. <html:form action = "LoginAction" focus = "username"> <table> <tr><td align = "right">User name: </td> <td><html:text property = "username"/> </td></tr> <tr><td align = "right">Password: </td><td><html:password property = "password" redisplay = "false"/></td></tr> </table> </html:form> Snippet from struts-html-1.1.tld: <tag> <name>password</name> <tagclass>org.apache.struts.taglib.html.PasswordTag</tagclass> <attribute> <name>redisplay</name> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> </tag> Resulting HTML: Having trouble getting this to post as code but the relevant part is an input tag of type 'password' with no reference to redisplay, autocomplete, etc. It is my understanding that the redisplay element should be passed through Struts to appear in the HTML.

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  • Can Spring access-denied-handler refer to popup?

    - by Rens Groenveld
    I am working with Spring Security 3.1.x and have implemented method annotation securities. As I want, when I perform a certain action while being logged in as a used that doesn't have the rights, I get a 403 acces is denied in my console! Perfect! Now I would like to catch this 403, and give the user a popup with a custom message. I don't want to redirect users to a page saying that they have no rights. Is there any way the access-denied-handler of Spring can take care of a popup? Or can it only redirect to another page? Maybe there are other options for me? Thanks in advance!

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  • Hashmap method not accepting defined parameters

    - by Ocasta Eshu
    My assignment is to implement a contact list in a HashMap. All has gone well except for the problem in the code below. the HashMap method put(K key, V value) isnt accepting the defined parameters String, List. public ContactList(){ private HashMap<String, List<String>> map; public void update(String name, List<String> number){ this.map.put(name, number) The error is: The method put(String, List<String>) is undefined for the type ContactList How do I correct this?

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  • package private static member class vs. package private class

    - by Helper Method
    I was writing two implementations of a linked list for an assignment, a doubly linked list and a circular doubly linked list. Now as the class representing a Link within the linked list is the same in both implementations, I want to use it in both. Now I wonder which approach would be better: Implement the Link class as a package private static member class in the first implementation and then use this class in the second implementation or make the Link class a package private class.

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  • Junit 4 test suite and individual test classes

    - by Hypnus
    I have a JUnit 4 test suite with BeforeClass and AfterClass methods that make a setup/teardown for the following test classes. What I need is to run the test classes also by them selves, but for that I need a setup/teardown scenario (BeforeClass and AfterClass or something like that) for each test class. The thing is that when I run the suite I do not want to execute the setup/teardown before and after each test class, I only want to execute the setup/teardown from the test suite (once). Is it possible ? Thanks in advance.

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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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  • Jaxb to generate the XML directly to the OutputStream

    - by sonu
    Hi, I have a 500Mb csv file. I need to convert it into XML file. I am using the Jaxb to created the xml file. It is working fine for small amout of data. but for large amout of data like 300 mb it is throwing out of memory exception. Can anyone tell me that How can I create each element and write it into a file without creating the whole tree using the jaxb?" Thanks Sonu

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  • What can you do in the ant Task.init() method?

    - by skiphoppy
    I'm developing a few custom ant tasks that all need to initialize the same objects. I wanted to initialize those object's in a common superclass that extends from Task, in the init() method. But I see from the lifecycle of an ant task that init() gets called before the tasks child elements and attributes are set. So all of the data I need for initializing those objects is unavailable during init(), if I am reading right. So, why is init() called at this point? What do you even know that you could use in init()? What could it be used for? (And is there some other method that I can rely on to be called before execute(), but after my data is available?)

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  • How to detect if a form input element of type file is empty

    - by Ankur
    I have some code which reads a file through a form field of type file <input type="file" ... /> I want to give the user another option of providing a url to a file rather than having to upload it as many are already online. How can I detect when this field is empty on the server side. I am using Apache Commons FileUpload FileItemStream item = iter.next(); name = item.getFieldName(); stream = item.openStream(); if(!item.isFormField()){ if(item.toString()!=""){ .... I need to detect when item is empty. The above code doesn't work, nor does using: if(item.equals(null)){ ....

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  • J2EE/EJB + service locator: is it safe to cache EJB Home lookup result ?

    - by Guillaume
    In a J2EE application, we are using EJB2 in weblogic. To avoid losing time building the initial context and looking up EJB Home interface, I'm considering the Service Locator Pattern. But after a few search on the web I found that event if this pattern is often recommended for the InitialContext caching, there are some negative opinion about the EJB Home caching. Questions: Is it safe to cache EJB Home lookup result ? What will happen if one my cluster node is no more working ? What will happen if I install a new version of the EJB without refreshing the service locator's cache ?

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  • Android - Can display a single Activity using two layout.xml files?

    - by Avadhani
    I had developed Android app having some screens with common UI format. The format in top-down approach is: Title Header (Two buttons, ImageView) Content Area- It will differ among Activities (contains ListView, Tabs, Buttons, TextView, WebView....) Footer Layout (Relative Layout with three Imagebuttons) I want to reformat the code in such a way that one xml contains Title Header and Footer Layout and other xml contains ListView,Tabs, Buttons.. based on the usage. Can i acheive this? Please help me with sample code/links....

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  • Is it possible to call the main(String[] args) after catching an exception?

    - by Jason
    I'm working on a Serpinski triangle program that asks the user for the levels of triangles to draw. In the interests of idiot-proofing my program, I put this in: Scanner input= new Scanner(System.in); System.out.println(msg); try { level= input.nextInt(); } catch (Exception e) { System.out.print(warning); //restart main method } Is it possible, if the user punches in a letter or symbol, to restart the main method after the exception has been caught?

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  • Set reference = null in finally block?

    - by deamon
    A colleague of mine sets reference to null in finally blocks. I think this is nonsense. public Something getSomething() { JDBCConnection jdbc=null; try { jdbc=JDBCManager.getConnection(JDBCTypes.MYSQL); } finally { JDBCManager.free(jdbc); jdbc=null; // <-- Useful or not? } } What do you think of it?

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