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  • ResultSet and aggregation

    - by kachanov
    Ok, I admit my situation is special There is a data system that supports SQL-92 and JDBC interface However the SQL requets are pretty expensive, and in my application I need to retreive the same data multiple times and aggregate it ("group by") on different fields to show different dimensions of the same data. For example on one screen I have three tables that show the same set or records but aggregated by City (1st grid), by Population (2nd grid), by number of babies (3rd grid) This amounts to 3 SQL queries (which is very slow), UNLESS anyone of you can suggest any idea any library from apache commons or from google code, so that I can select all records into ResultSet and get 3 arrays of data group by different fields from this single ResultSet. Am I'm missing some obvious and unexpected solution to this problem?

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  • Use HTTP PUT to create new cache (ehCache) running on the same Tomcat?

    - by socal_javaguy
    I am trying to send a HTTP PUT (in order to create a new cache and populate it with my generated JSON) to ehCache using my webservice which is on the same local tomcat instance. Am new to RESTful Web Services and am using JDK 1.6, Tomcat 7, ehCache, and JSON. I have my POJOs defined like this: Person POJO: import javax.xml.bind.annotation.XmlRootElement; @XmlRootElement public class Person { private String firstName; private String lastName; private List<House> houses; // Getters & Setters } House POJO: import javax.xml.bind.annotation.XmlRootElement; @XmlRootElement public class House { private String address; private String city; private String state; // Getters & Setters } Using a PersonUtil class, I hardcoded the POJOs as follows: public class PersonUtil { public static Person getPerson() { Person person = new Person(); person.setFirstName("John"); person.setLastName("Doe"); List<House> houses = new ArrayList<House>(); House house = new House(); house.setAddress("1234 Elm Street"); house.setCity("Anytown"); house.setState("Maine"); houses.add(house); person.setHouses(houses); return person; } } Am able to create a JSON response per a GET request: @Path("") public class MyWebService{ @GET @Produces(MediaType.APPLICATION_JSON) public Person getPerson() { return PersonUtil.getPerson(); } } When deploying the war to tomcat and pointing the browser to http://localhost:8080/personservice/ Generated JSON: { "firstName" : "John", "lastName" : "Doe", "houses": [ { "address" : "1234 Elmstreet", "city" : "Anytown", "state" : "Maine" } ] } So far, so good, however, I have a different app which is running on the same tomcat instance (and has support for REST): http://localhost:8080/ehcache/rest/ While tomcat is running, I can issue a PUT like this: echo "Hello World" | curl -S -T - http://localhost:8080/ehcache/rest/hello/1 When I "GET" it like this: curl http://localhost:8080/ehcache/rest/hello/1 Will yield: Hello World What I need to do is create a POST which will put my entire Person generated JSON and create a new cache: http://localhost:8080/ehcache/rest/person And when I do a "GET" on this previous URL, it should look like this: { "firstName" : "John", "lastName" : "Doe", "houses": [ { "address" : "1234 Elmstreet", "city" : "Anytown", "state" : "Maine" } ] } So, far, this is what my PUT looks like: @PUT @Path("/ehcache/rest/person") @Produces(MediaType.APPLICATION_JSON) @Consumes(MediaType.APPLICATION_JSON) public Response createCache() { ResponseBuilder response = Response.ok(PersonUtil.getPerson(), MediaType.APPLICATION_JSON); return response.build(); } Question(s): (1) Is this the correct way to write the PUT? (2) What should I write inside the createCache() method to have it PUT my generated JSON into: http://localhost:8080/ehcache/rest/person (3) What would the command line CURL comment look like to use the PUT? Thanks for taking the time to read this...

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  • write behind cache Ehcache new feature?

    - by cometta
    Hi, i looking for guide/document/tutorial on how to use this new feature write-behind-cache in ehcache? Is there any demo in spring+jpa+ehcache+hibernate? just to clariyfing, write-behind-cache mean each time we persist entity, it will be written into cache rather than into database correct?

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  • Long running method causing race condition

    - by keeleyt83
    Hi, I'm relatively new with hibernate so please be gentle. I'm having an issue with a long running method (~2 min long) and changing the value of a status field on an object stored in the DB. The pseudo-code below should help explain my issue. public foo(thing) { if (thing.getStatus() == "ready") { thing.setStatus("finished"); doSomethingAndTakeALongTime(); } else { // Thing already has a status of finished. Send the user back a message. } } The pseudo-code shouldn't take much explanation. I want doSomethingAndTakeALongTime() to run, but only if it has a status of "ready". My issue arises whenever it takes 2 minutes for doSomethingAndTakeALongTime() to finish and the change to thing's status field doesn't get persisted to the database until it leaves foo(). So another user can put in a request during those 2 minutes and the if statement will evaluate to true. I've already tried updating the field and flushing the session manually, but it didn't seem to work. I'm not sure what to do from here and would appreciate any help. PS: My hibernate session is managed by spring.

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  • which toString() method can be used performance wise??

    - by Mrityunjay
    hi, I am working on one project for performance enhancement. I had one doubt, while we are during a process, we tend to trace the current state of the DTO and entity used. So, for this we have included toString() method in all POJOs for the same. I have now implemented toString() in three different ways which are following :- public String toString() { return "POJO :" + this.class.getName() + " RollNo :" + this.rollNo + " Name :" + this.name; } public String toString() { StringBuffer buff = new StringBuffer("POJO :").append(this.class.getName()).append(" RollNo :").append(this.rollNo).append(" Name :").append(this.name); return buff.toString(); } public String toString() { StringBuilder builder = new StringBuilder("POJO :").append(this.class.getName()).append(" RollNo :").append(this.rollNo).append(" Name :").append(this.name); return builder .toString(); } can anyone please help me to find out which one is best and should be used for enhancing performance.

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  • inserted in multiple tables of database at a time

    - by rajkumari
    can we work with multiple tables of database with same connection object of database at same time . suppose i have inserted value in table 1 and at same time also inserted value in table 2 of data base with same object of data base connection. I am using sqlite database in code and getting database locked exception while commit() .

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  • Ready to use TSP library

    - by Max
    Hi, I'm currently doing a project that requires some fast TSP solving (about 50-100 nodes in 2 seconds). There are a lots of approximation algorithms out there, but I don't have time nor will to analyze them and code them myself. Are there any free libraries that can solve TSP problem (approximation will do too)? Something like sortedNodes = solveTspPrettyPlease(nodes, 2sec) would be just great. Thanks in advance.

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  • Swing Timer in Conjunction with Possible Long-running Background Task

    - by javacavaj
    I need to perform a task repeatedly that affects both GUI-related and non GUI-related objects. One caveat is that no action should performed if the previous task had not completed when the next timer event is fired. My initial thoughts are to use a SwingTimer in conjunction with a javax.swing.SwingWorker object. The general setup would look like this. class { timer = new Timer(speed, this); timer.start(); public void actionPerformed(ActionEvent e) { SwingWorker worker = new SwingWorker() { @Override public ImageIcon[] doInBackground() { // potential long running task } @Override public void done() { // update GUI on event dispatch thread when complete } } } Some potential issues I see with this approach are: 1) Multiple SwingWorkers will be active if a worker has not completed before the next ActionEvent is fired by the timer. 2) A SwingWorker is only designed to be executed once, so holding a reference to the worker and reusing (is not?) a viable option. Is there a better way to achieve this?

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  • Maven Ant BuildException with maven-antrun-plugin ... unable to find javac compiler

    - by robsbobs
    Im trying to make Maven call an ANT build for some legacy code. the ant build builds correctly through ant however when i call it using the maven ant plugin it fails with the following error: [ ERROR] Failed to execute goal org.apache.maven.plugins:maven-antrun-plugin:1.6:run (default) on project CoreServices: An Ant BuildException has occured: The following error occurred while executing this line: [ERROR] C:\dev\projects\build\build.xml:158: The following error occurred while executing this line: [ERROR] C:\dev\projects\build\build.xml:62: The following error occurred while executing this line: [ERROR] C:\dev\projects\build\build.xml:33: The following error occurred while executing this line: [ERROR] C:\dev\projects\ods\build.xml:41: Unable to find a javac compiler; [ERROR] com.sun.tools.javac.Main is not on the classpath. [ERROR] Perhaps JAVA_HOME does not point to the JDK. [ERROR] It is currently set to "C:\bea\jdk150_11\jre" My javac exists at C:\bea\jdk150_11\bin and this works for all other things. Im not sure where Maven is getting this version of JAVA_HOME. JAVA_HOME in windows envionrmental variables is set to C:\bea\jdk150_11\ as it should be. The Maven code that im using to call the build.xml is <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-antrun-plugin</artifactId> <version>1.6</version> <executions> <execution> <phase>install</phase> <configuration> <target> <ant antfile="../build/build.xml" target="deliver" > </ant> </target> </configuration> <goals> <goal>run</goal> </goals> </execution> </executions> </plugin> </plugins> </build>

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  • How to retrieve the ordered list of best articles having a minimum number of votes by using HSQL ?

    - by fabien7474
    I have a Vote domain class from my grails application containing properties like article_id and note I want to HQL query the Vote domain class in order to retrieve the 5 best rated articles having at least 10 votes. I tried : SELECT v.article_id, avg(v.note), count(*) FROM vote v where count(*) >= 10 group by v.article_id order by avg(v.note) desc limit 5; But unfortunately the insertion of where count(*) >= 10 throws an error. How can I do that in a simple way? Thank you for your help.

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  • Servlets, long operations

    - by asrijaal
    Hi there, I'm refactoring a big piece of code atm where a long taking operation is executed in a servlet. Now sometimes I don't get a response after the operation has finished. (It has finished because it is printed into the logs) What I wish to achieve would some "fire and forget" behavior by the servlet. I would pass my params to the action and the servlet would immediately return a status (something like: the operation has started, check your logs for further info) Is this possible with servlet 2.5 spec? I think I could get such a behavior with JMS maybe any other solutions out there?

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  • How to define RequestMapping prioritization

    - by James Skidmore
    I have a situation where I need the following RequestMapping: @RequestMapping(value={"/{section}"}) ...method implementation here... @RequestMapping(value={"/support"}) ...method implementation here... There is an obvious conflict. My hope was that Spring would resolve this automatically and map /support to the second method, and everything else to the first, but it instead maps /support to the first method. How can I tell Spring to allow an explicit RequestMapping to override a RequestMapping with a PathVariable in the same place? (Edit - this is simplified, I know that having those two RequestMapping alone wouldn't make much sense)

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  • for loop will not loop

    - by Bjørn Jostein Aurheim
    I have a for loop that I will use to compute time intervals to add to an ArrayList. The problem is that I can not prove that the for loop is being executed. Nothing is printed when using the system.out.println() statement, and nothing is added to the array from inside the loop ... any sugestions? // lager tidspunkter og legger disse inn i en Array kalt tider tid.setTimer(16); tid.setMinutter(0); tid.setSekunder(0); tider.add(tid.asString());// String "16:00" is added as it should System.out.println("tiden er: "+tid.asString());// gives 16:00 printed for(int i=0;i>12;i++){ System.out.println("er i løkken");// gives nothing printed tid.increaseMinutter(30); System.out.println(tid.asString());// gives nothing printed tider.add(tid.asString()); }

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  • Is J2SE a framework?

    - by Alvin
    Hello, I want to know is this legitimate to say J2SE a framework? If J2SE is a framework, then why there is a collection framework? Isn't collection framework inside J2SE? Please help me!

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  • How to write a jUnit test for this class?

    - by flash
    Hi, I would like to know what's the best approach to test the method "pushEvent()" in the following class with a jUnit test. My problem is, that the private method "callWebsite()" always requires a connection to the network. How can I avoid this requirement or refactor my class that I can test it without a connection to the network? class MyClass { public String pushEvent (Event event) { //do something here String url = constructURL (event); //construct the website url String response = callWebsite (url); return response; } private String callWebsite (String url) { try { URL requestURL = new URL (url); HttpURLConnection connection = null; connection = (HttpURLConnection) requestURL.openConnection (); String responseMessage = responseParser.getResponseMessage (connection); return responseMessage; } catch (MalformedURLException e) { e.printStackTrace (); return e.getMessage (); } catch (IOException e) { e.printStackTrace (); return e.getMessage (); } } }

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  • leiningen - how to add dependencies for local jars?

    - by signalseeker
    Hi, I want to use leiningen to build and develop my clojure project. Is there a way to modify project.clj to tell it to pick some jars from local directories? I have some proprietary jars that cannot be uploaded to public repos. Also, can leiningen be used to maintain a "lib" directory for clojure projects? If a bunch of my clojure projects share the same jars, I don't want to maintain a separate copy for each of them. Thanks

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  • Ref to map vs. map to refs vs. multiple refs

    - by mikera
    I'm working on a GUI application in Swing+Clojure that requires various mutable pieces of data (e.g. scroll position, user data, filename, selected tool options etc.). I can see at least three different ways of handling this set of data: Create a ref to a map of all the data: (def data (ref { :filename "filename.xml" :scroll [0 0] })) Create a map of refs to the individual data elements: (def datamap { :filename (ref "filename.xml") :scroll (ref [0 0]) })) Create a separate ref for each in the namespace: (def scroll (ref [0 0])) (def filename (ref "filename.xml")) Note: This data will be accessed concurrently, e.g. by background processing threads or the Swing event handling thread. However there probably isn't a need for consistent transactional updates of multiple elements. What would be your recommended approach and why?

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  • html:checkbox query

    - by sarah
    Hi All, i have the following code . and in Form is have property called isActive of type char ,how would i get the checked value of it ,i am getting some symbols like 'o' if checked. I am using userform.getIsActive() ,where i am going wrong .I want 'y' or 'n' values

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  • Why baseclass calls method of subclass?

    - by twlkyao
    I encounter some code like the following: BaseClass: public class BaseClass { String name = "Base"; public BaseClass() { printName(); } public void printName() { System.out.println(name + "——Base"); } } DrivedClass: public class SubClass extends BaseClass { String name = "Sub"; public SubClass() { printName(); } public void printName() { System.out.println(name + "——Sub"); } public static void main(String[] args) { new SubClass(); } } When run the code, the output is: null——Sub Sub——Sub while it should be: Base——Base Sub——Sub I wonder why the BaseClass constructor calls the SubClass method, can anybody explain this? Thanks in advance.

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  • Just need someone familiar with HTTPClient to check over a piece of code

    - by jax
    here are two little helper methods I have made for downloading files. I have had to mix and match different tutorials of the web to get what I have here. Now is there anything that I have done blatantly wrong here? public static InputStream simplePostRequest(URL url, List<NameValuePair> postData) throws ClientProtocolException, IOException { DefaultHttpClient httpclient = new DefaultHttpClient(); HttpPost postMethod=new HttpPost(url.toExternalForm()); postMethod.setEntity(new UrlEncodedFormEntity(postData, HTTP.UTF_8)); HttpResponse response = httpclient.execute(postMethod); HttpEntity entity = response.getEntity(); return entity.getContent(); } public static InputStream simpleGetRequest(URL url, List<NameValuePair> queryString) throws ClientProtocolException, IOException { Uri.Builder uri = new Uri.Builder(); uri.path(url.getPath()); for(NameValuePair nvp: queryString) { uri.appendQueryParameter(nvp.getName(), nvp.getValue()); } DefaultHttpClient httpClient = new DefaultHttpClient(); HttpHost host = new HttpHost(url.getHost()); HttpResponse response = httpClient.execute(host, new HttpGet(uri.build().toString())); HttpEntity entity = response.getEntity(); return entity.getContent(); }

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