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  • Java: Best approach to have a long list of variables needed all the time without consuming memory?

    - by evilReiko
    I wrote an abstract class to contain all rules of the application because I need them almost everywhere in my application. So most of what it contains is static final variables, something like this: public abstract class appRules { public static final boolean IS_DEV = true; public static final String CLOCK_SHORT_TIME_FORMAT = "something"; public static final String CLOCK_SHORT_DATE_FORMAT = "something else"; public static final String CLOCK_FULL_FORMAT = "other thing"; public static final int USERNAME_MIN = 5; public static final int USERNAME_MAX = 16; // etc. } The class is big and contains LOTS of such variables. My Question: Isn't setting static variables means these variables are floating in memory all the time? Do you suggest insteading of having an abstract class, I have a instantiable class with non-static variables (just public final), so I instantiate the class and use the variables only when I need them. Or is what am I doing is completely wrong approach and you suggest something else?

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  • Terminating a long-executing thread and then starting a new one in response to user changing parameters via UI in an applet

    - by user1817170
    I have an applet which creates music using the JFugue API and plays it for the user. It allows the user to input a music phrase which the piece will be based on, or lets them choose to have a phrase generated randomly. I had been using the following method (successfully) to simply stop and start the music, which runs in a thread using the Player class from JFugue. I generate the music using my classes and user input from the applet GUI...then... private playerThread pthread; private Thread threadPlyr; private Player player; (from variables declaration) public void startMusic(Pattern p) // pattern is a JFugue object which holds the generated music { if (pthread == null) { pthread = new playerThread(); } else { pthread = null; pthread = new playerThread(); } if (threadPlyr == null) { threadPlyr = new Thread(pthread); } else { threadPlyr = null; threadPlyr = new Thread(pthread); } pthread.setPattern(p); threadPlyr.start(); } class playerThread implements Runnable // plays midi using jfugue Player { private Pattern pt; public void setPattern(Pattern p) { pt = p; } @Override public void run() { try { player.play(pt); // takes a couple mins or more to execute resetGUI(); } catch (Exception exception) { } } } And the following to stop music when user presses the stop/start button while Player.isPlaying() is true: public void stopMusic() { threadPlyr.interrupt(); threadPlyr = null; pthread = null; player.stop(); } Now I want to implement a feature which will allow the user to change parameters while the music is playing, create an updated music pattern, and then play THAT pattern. Basically, the idea is to make it simulate "real time" adjustments to the generated music for the user. Well, I have been beating my head against the wall on this for a couple of weeks. I've read all the standard java documentation, researched, read, and searched forums, and I have tried many different ideas, none of which have succeeded. The problem I've run into with all approaches I've tried is that when I start the new thread with the new, updated musical pattern, all the old threads ALSO start, and there is a cacophony of unintelligible noise instead of my desired output. From what I've gathered, the issue seems to be that all the methods I've come across require that the thread is able to periodically check the value of a "flag" variable and then shut itself down from within its "run" block in response to that variable. However, since my thread makes a call that takes several minutes minimum to execute (playing the music), and I need to terminate it WHILE it is executing this, there is really no safe way to do so. So, I'm wondering if there is something I'm missing when it comes to threads, or if perhaps I can accomplish my goal using a totally different approach. Any ideas or guidance is greatly appreciated! Thank you!

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  • data is not inserting in my db table [closed]

    - by Sarojit Chakraborty
    Please see my below(SubjectDetailsDao.java) code of addZoneToDb method. My debugger is nicely running upto ** session.getTransaction().commit();** code. but after that debugger stops,I do not know why it stops after that line? .And because of this i am unable to insert my data into my database table. I don't know what to do.Why it is not inserting my data into my database table? Plz help me for this. H Now i am getting this Error: Struts Problem Report Struts has detected an unhandled exception: Messages: org.hibernate.event.PreInsertEvent.getSource()Lorg/hibernate/event/EventSource; File: org/hibernate/validator/event/ValidateEventListener.java Line number: 172 Stacktraces java.lang.reflect.InvocationTargetException sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) java.lang.reflect.Method.invoke(Method.java:601) com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:441) com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:280) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:243) com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:165) com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:252) org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68) com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:122) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:195) com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:195) com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:179) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:75) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:94) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:235) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:89) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:130) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:267) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:126) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:138) com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:165) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:179) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:176) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:52) org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:488) org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77) org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:91) org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:240) org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:164) org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:498) org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164) org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100) org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:562) org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:394) org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:243) org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:188) org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:302) java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) java.lang.Thread.run(Thread.java:722) java.lang.NoSuchMethodError: org.hibernate.event.PreInsertEvent.getSource()Lorg/hibernate/event/EventSource; org.hibernate.validator.event.ValidateEventListener.onPreInsert(ValidateEventListener.java:172) org.hibernate.action.EntityInsertAction.preInsert(EntityInsertAction.java:156) org.hibernate.action.EntityInsertAction.execute(EntityInsertAction.java:49) org.hibernate.engine.ActionQueue.execute(ActionQueue.java:250) org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:234) org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:141) org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:298) org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:27) org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1000) org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:338) org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:106) v.esoft.dao.SubjectdetailsDAO.SubjectdetailsDAO.addZoneToDb(SubjectdetailsDAO.java:185) v.esoft.actions.LoginAction.datatobeinsert(LoginAction.java:53) sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) java.lang.reflect.Method.invoke(Method.java:601) com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:441) com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:280) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:243) com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:165) com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:252) org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68) ............................... ............................... SubjectDetailsDao.java(I have problem in addZoneToDb) package v.esoft.dao.SubjectdetailsDAO; import java.text.SimpleDateFormat; import java.util.ArrayList; import java.util.Iterator; import java.util.List; import org.hibernate.HibernateException; import org.hibernate.Query; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.Transaction; import org.hibernate.criterion.Order; import com.opensymphony.xwork2.ActionSupport; import v.esoft.connection.HibernateUtil; import v.esoft.pojos.Subjectdetails; public class SubjectdetailsDAO extends ActionSupport { private static Session session = null; private static SessionFactory sessionFactory = null; static Transaction transaction = null; private String currentDate; SimpleDateFormat formatter1 = new SimpleDateFormat("yyyy-MM-dd"); private java.util.Date currentdate; public SubjectdetailsDAO() { sessionFactory = HibernateUtil.getSessionFactory(); SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd"); currentdate = new java.util.Date(); currentDate = formatter.format(currentdate); } public List getAllCustomTempleteRoutinesForGrid() { List list = new ArrayList(); try { session = sessionFactory.openSession(); list = session.createCriteria(Subjectdetails.class).addOrder(Order.desc("subjectId")).list(); } catch (Exception e) { System.out.println("Exepetion in getAllCustomTempleteRoutines" + e); } finally { try { // HibernateUtil.shutdown(); } catch (Exception e) { System.out.println("Exception In getExerciseListByLoginId Resource closing :" + e); } } return list; } //**showing list on grid private static List<Subjectdetails> custLst=new ArrayList<Subjectdetails>(); static int total=50; static { SubjectdetailsDAO cts = new SubjectdetailsDAO(); Iterator iterator1 = cts.getAllCustomTempleteRoutinesForGrid().iterator(); while (iterator1.hasNext()) { Subjectdetails get = (Subjectdetails) iterator1.next(); custLst.add(get); } } /****************************************update Routines List by WorkId************************************/ public int updatesub(Subjectdetails s) { int updated = 0; try { session = sessionFactory.openSession(); transaction = session.beginTransaction(); Query query = session.createQuery("UPDATE Subjectdetails set subjectName = :routineName1 WHERE subjectId=:workoutId1"); query.setString("routineName1", s.getSubjectName()); query.setInteger("workoutId1", s.getSubjectId()); updated = query.executeUpdate(); if (updated != 0) { } transaction.commit(); } catch (Exception e) { if (transaction != null && transaction.isActive()) { try { transaction.rollback(); } catch (Exception e1) { System.out.println("Exception in addUser() Rollback :" + e1); } } } finally { try { session.flush(); session.close(); } catch (Exception e) { System.out.println("Exception In addUser Resource closing :" + e); } } return updated; } /****************************************update Routines List by WorkId************************************/ public int addSubjectt(Subjectdetails s) { int inserted = 0; Subjectdetails ss=new Subjectdetails(); try { session = sessionFactory.openSession(); transaction = session.beginTransaction(); ss. setSubjectName(s.getSubjectName()); session.save(ss); System.out.println("Successfully data insert in database"); inserted++; if (inserted != 0) { } transaction.commit(); } catch (Exception e) { if (transaction != null && transaction.isActive()) { try { transaction.rollback(); } catch (Exception e1) { System.out.println("Exception in addUser() Rollback :" + e1); } } } finally { try { session.flush(); session.close(); } catch (Exception e) { System.out.println("Exception In addUser Resource closing :" + e); } } return inserted; } /******************************************Get all Routines List by LoginID************************************/ public List getSubjects() { List list = null; try { session = sessionFactory.openSession(); list = session.createCriteria(Subjectdetails.class).list(); } catch (Exception e) { System.out.println("Exception in getRoutineList() :" + e); } finally { try { session.flush(); session.close(); } catch (Exception e) { System.out.println("Exception In getUserList Resource closing :" + e); } } return list; } //---\ public int addZoneToDb(String countryName, Integer loginId) { int inserted = 0; try { System.out.println("---------1--------"); Session session = HibernateUtil.getSessionFactory().openSession(); System.out.println("---------2------session--"+session); session.beginTransaction(); Subjectdetails country = new Subjectdetails(countryName, loginId, currentdate, loginId, currentdate); System.out.println("---------2------country--"+country); session.save(country); System.out.println("-------after save--"); inserted++; session.getTransaction().commit(); System.out.println("-------after commits--"); } catch (Exception e) { if (transaction != null && transaction.isActive()) { try { transaction.rollback(); } catch (Exception e1) { } } } finally { try { } catch (Exception e) { } } return inserted; } //-- public int nextId() { return total++; } public List<Subjectdetails> buildList() { return custLst; } public static int count() { return custLst.size(); } public static List<Subjectdetails> find(int o,int q) { return custLst.subList(o, q); } public void save(Subjectdetails c) { custLst.add(c); } public static Subjectdetails findById(Integer id) { try { for(Subjectdetails c:custLst) { if(c.getSubjectId()==id) { return c; } } } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } return null; } public void update(Subjectdetails c) { for(Subjectdetails x:custLst) { if(x.getSubjectId()==c.getSubjectId()) { x.setSubjectName(c.getSubjectName()); } } } public void delete(Subjectdetails c) { custLst.remove(c); } public static List<Subjectdetails> findNotById(int id, int from,int to) { List<Subjectdetails> subLst=custLst.subList(from, to); List<Subjectdetails> temp=new ArrayList<Subjectdetails>(); for(Subjectdetails c:subLst) { if(c.getSubjectId()!=id) { temp.add(c); } } return temp; } public static List<Subjectdetails> findLesserAsId(int id, int from,int to) { List<Subjectdetails> subLst=custLst.subList(from, to); List<Subjectdetails> temp=new ArrayList<Subjectdetails>(); for(Subjectdetails c:subLst) { if(c.getSubjectId()<=id) { temp.add(c); } } return temp; } public static List<Subjectdetails> findGreaterAsId(int id, int from,int to) { List<Subjectdetails> subLst=custLst.subList(from, to); List<Subjectdetails> temp=new ArrayList<Subjectdetails>(); for(Subjectdetails c:subLst) { if(c.getSubjectId()>=id) { temp.add(c); } } return temp; } } Subjectdetails.hbm.xml <hibernate-mapping> <class name="vb.sofware.pojos.Subjectdetails" table="subjectdetails" catalog="vbsoftware"> <id name="subjectId" type="int"> <column name="subject_id" /> <generator class="increment"/> </id> <property name="subjectName" type="string"> <column name="subject_name" length="150" /> </property> <property name="createrId" type="java.lang.Integer"> <column name="creater_id" /> </property> <property name="createdDate" type="timestamp"> <column name="created_date" length="19" /> </property> <property name="updateId" type="java.lang.Integer"> <column name="update_id" /> </property> <property name="updatedDate" type="timestamp"> <column name="updated_date" length="19" /> </property> </class> </hibernate-mapping> My POJO - Subjectdetails.java package v.esoft.pojos; // Generated Oct 6, 2012 1:58:21 PM by Hibernate Tools 3.4.0.CR1 import java.util.Date; /** * Subjectdetails generated by hbm2java */ public class Subjectdetails implements java.io.Serializable { private int subjectId; private String subjectName; private Integer createrId; private Date createdDate; private Integer updateId; private Date updatedDate; public Subjectdetails( String subjectName) { //this.subjectId = subjectId; this.subjectName = subjectName; } public Subjectdetails() { } public Subjectdetails(int subjectId) { this.subjectId = subjectId; } public Subjectdetails(int subjectId, String subjectName, Integer createrId, Date createdDate, Integer updateId, Date updatedDate) { this.subjectId = subjectId; this.subjectName = subjectName; this.createrId = createrId; this.createdDate = createdDate; this.updateId = updateId; this.updatedDate = updatedDate; } public Subjectdetails( String subjectName, Integer createrId, Date createdDate, Integer updateId, Date updatedDate) { this.subjectName = subjectName; this.createrId = createrId; this.createdDate = createdDate; this.updateId = updateId; this.updatedDate = updatedDate; } public int getSubjectId() { return this.subjectId; } public void setSubjectId(int subjectId) { this.subjectId = subjectId; } public String getSubjectName() { return this.subjectName; } public void setSubjectName(String subjectName) { this.subjectName = subjectName; } public Integer getCreaterId() { return this.createrId; } public void setCreaterId(Integer createrId) { this.createrId = createrId; } public Date getCreatedDate() { return this.createdDate; } public void setCreatedDate(Date createdDate) { this.createdDate = createdDate; } public Integer getUpdateId() { return this.updateId; } public void setUpdateId(Integer updateId) { this.updateId = updateId; } public Date getUpdatedDate() { return this.updatedDate; } public void setUpdatedDate(Date updatedDate) { this.updatedDate = updatedDate; } } And my Sql query is CREATE TABLE IF NOT EXISTS `subjectdetails` ( `subject_id` int(3) NOT NULL, `subject_name` varchar(150) DEFAULT NULL, `creater_id` int(5) DEFAULT NULL, `created_date` datetime DEFAULT NULL, `update_id` int(5) DEFAULT NULL, `updated_date` datetime DEFAULT NULL, PRIMARY KEY (`subject_id`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1;

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  • Foreign key constraints in Android using SQLite? on Delete cascade.

    - by LordSnoutimus
    I have two tables: tracks and waypoints, a track can have many waypoints, but a waypoint is assigned to only 1 track. In the way points table I have a column called "trackidfk" which inserts the track_ID once a track is made, however I have not setup Foreign Key constraints on this column. When I delete a track I want to delete the assigned waypoints, is this possible?. I read about using Triggers but I don't think they are supported in Android. To create the waypoints table: public void onCreate(SQLiteDatabase db) { db.execSQL("CREATE TABLE " + TABLE_NAME + " (" + _ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " + LONGITUDE + " INTEGER," + LATITUDE + " INTEGER," + TIME + " INTEGER,"+ TRACK_ID_FK + " INTEGER );");

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  • Java ThreadPoolExecutor getting stuck while using ArrayBlockingQueue

    - by Ravi Rao
    Hi, I'm working on some application and using ThreadPoolExecutor for handling various tasks. ThreadPoolExecutor is getting stuck after some duration. To simulate this in a simpler environment, I've written a simple code where I'm able to simulate the issue. import java.util.concurrent.ArrayBlockingQueue; import java.util.concurrent.RejectedExecutionHandler; import java.util.concurrent.ThreadPoolExecutor; import java.util.concurrent.TimeUnit; public class MyThreadPoolExecutor { private int poolSize = 10; private int maxPoolSize = 50; private long keepAliveTime = 10; private ThreadPoolExecutor threadPool = null; private final ArrayBlockingQueue&lt;Runnable&gt; queue = new ArrayBlockingQueue&lt;Runnable&gt;( 100000); public MyThreadPoolExecutor() { threadPool = new ThreadPoolExecutor(poolSize, maxPoolSize, keepAliveTime, TimeUnit.SECONDS, queue); threadPool.setRejectedExecutionHandler(new RejectedExecutionHandler() { @Override public void rejectedExecution(Runnable runnable, ThreadPoolExecutor threadPoolExecutor) { System.out .println(&quot;Execution rejected. Please try restarting the application.&quot;); } }); } public void runTask(Runnable task) { threadPool.execute(task); } public void shutDown() { threadPool.shutdownNow(); } public ThreadPoolExecutor getThreadPool() { return threadPool; } public void setThreadPool(ThreadPoolExecutor threadPool) { this.threadPool = threadPool; } public static void main(String[] args) { MyThreadPoolExecutor mtpe = new MyThreadPoolExecutor(); for (int i = 0; i &lt; 1000; i++) { final int j = i; mtpe.runTask(new Runnable() { @Override public void run() { System.out.println(j); } }); } } } Try executing this code a few times. It normally print outs the number on console and when all threads end, it exists. But at times, it finished all task and then is not getting terminated. The thread dump is as follows: MyThreadPoolExecutor [Java Application] MyThreadPoolExecutor at localhost:2619 (Suspended) Daemon System Thread [Attach Listener] (Suspended) Daemon System Thread [Signal Dispatcher] (Suspended) Daemon System Thread [Finalizer] (Suspended) Object.wait(long) line: not available [native method] ReferenceQueue&lt;T&gt;.remove(long) line: not available ReferenceQueue&lt;T&gt;.remove() line: not available Finalizer$FinalizerThread.run() line: not available Daemon System Thread [Reference Handler] (Suspended) Object.wait(long) line: not available [native method] Reference$Lock(Object).wait() line: 485 Reference$ReferenceHandler.run() line: not available Thread [pool-1-thread-1] (Suspended) Unsafe.park(boolean, long) line: not available [native method] LockSupport.park(Object) line: not available AbstractQueuedSynchronizer$ConditionObject.await() line: not available ArrayBlockingQueue&lt;E&gt;.take() line: not available ThreadPoolExecutor.getTask() line: not available ThreadPoolExecutor$Worker.run() line: not available Thread.run() line: not available Thread [pool-1-thread-2] (Suspended) Unsafe.park(boolean, long) line: not available [native method] LockSupport.park(Object) line: not available AbstractQueuedSynchronizer$ConditionObject.await() line: not available ArrayBlockingQueue&lt;E&gt;.take() line: not available ThreadPoolExecutor.getTask() line: not available ThreadPoolExecutor$Worker.run() line: not available Thread.run() line: not available Thread [pool-1-thread-3] (Suspended) Unsafe.park(boolean, long) line: not available [native method] LockSupport.park(Object) line: not available AbstractQueuedSynchronizer$ConditionObject.await() line: not available ArrayBlockingQueue&lt;E&gt;.take() line: not available ThreadPoolExecutor.getTask() line: not available ThreadPoolExecutor$Worker.run() line: not available Thread.run() line: not available Thread [pool-1-thread-4] (Suspended) Unsafe.park(boolean, long) line: not available [native method] LockSupport.park(Object) line: not available AbstractQueuedSynchronizer$ConditionObject.await() line: not available ArrayBlockingQueue&lt;E&gt;.take() line: not available ThreadPoolExecutor.getTask() line: not available ThreadPoolExecutor$Worker.run() line: not available Thread.run() line: not available Thread [pool-1-thread-6] (Suspended) Unsafe.park(boolean, long) line: not available [native method] LockSupport.park(Object) line: not available AbstractQueuedSynchronizer$ConditionObject.await() line: not available ArrayBlockingQueue&lt;E&gt;.take() line: not available ThreadPoolExecutor.getTask() line: not available ThreadPoolExecutor$Worker.run() line: not available Thread.run() line: not available Thread [pool-1-thread-8] (Suspended) Unsafe.park(boolean, long) line: not available [native method] LockSupport.park(Object) line: not available AbstractQueuedSynchronizer$ConditionObject.await() line: not available ArrayBlockingQueue&lt;E&gt;.take() line: not available ThreadPoolExecutor.getTask() line: not available ThreadPoolExecutor$Worker.run() line: not available Thread.run() line: not available Thread [pool-1-thread-5] (Suspended) Unsafe.park(boolean, long) line: not available [native method] LockSupport.park(Object) line: not available AbstractQueuedSynchronizer$ConditionObject.await() line: not available ArrayBlockingQueue&lt;E&gt;.take() line: not available ThreadPoolExecutor.getTask() line: not available ThreadPoolExecutor$Worker.run() line: not available Thread.run() line: not available Thread [pool-1-thread-10] (Suspended) Unsafe.park(boolean, long) line: not available [native method] LockSupport.park(Object) line: not available AbstractQueuedSynchronizer$ConditionObject.await() line: not available ArrayBlockingQueue&lt;E&gt;.take() line: not available ThreadPoolExecutor.getTask() line: not available ThreadPoolExecutor$Worker.run() line: not available Thread.run() line: not available Thread [pool-1-thread-9] (Suspended) Unsafe.park(boolean, long) line: not available [native method] LockSupport.park(Object) line: not available AbstractQueuedSynchronizer$ConditionObject.await() line: not available ArrayBlockingQueue&lt;E&gt;.take() line: not available ThreadPoolExecutor.getTask() line: not available ThreadPoolExecutor$Worker.run() line: not available Thread.run() line: not available Thread [pool-1-thread-7] (Suspended) Unsafe.park(boolean, long) line: not available [native method] LockSupport.park(Object) line: not available AbstractQueuedSynchronizer$ConditionObject.await() line: not available ArrayBlockingQueue&lt;E&gt;.take() line: not available ThreadPoolExecutor.getTask() line: not available ThreadPoolExecutor$Worker.run() line: not available Thread.run() line: not available Thread [DestroyJavaVM] (Suspended) C:\Program Files\Java\jre1.6.0_07\bin\javaw.exe (Jun 17, 2010 10:42:33 AM) In my actual application,ThreadPoolExecutor threads go in this state and then it stops responding. Regards, Ravi Rao

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  • Liskov Substitution Principle and the Oft Forgot Third Wheel

    - by Stacy Vicknair
    Liskov Substitution Principle (LSP) is a principle of object oriented programming that many might be familiar with from the SOLID principles mnemonic from Uncle Bob Martin. The principle highlights the relationship between a type and its subtypes, and, according to Wikipedia, is defined by Barbara Liskov and Jeanette Wing as the following principle:   Let be a property provable about objects of type . Then should be provable for objects of type where is a subtype of .   Rectangles gonna rectangulate The iconic example of this principle is illustrated with the relationship between a rectangle and a square. Let’s say we have a class named Rectangle that had a property to set width and a property to set its height. 1: Public Class Rectangle 2: Overridable Property Width As Integer 3: Overridable Property Height As Integer 4: End Class   We all at some point here that inheritance mocks an “IS A” relationship, and by gosh we all know square IS A rectangle. So let’s make a square class that inherits from rectangle. However, squares do maintain the same length on every side, so let’s override and add that behavior. 1: Public Class Square 2: Inherits Rectangle 3:  4: Private _sideLength As Integer 5:  6: Public Overrides Property Width As Integer 7: Get 8: Return _sideLength 9: End Get 10: Set(value As Integer) 11: _sideLength = value 12: End Set 13: End Property 14:  15: Public Overrides Property Height As Integer 16: Get 17: Return _sideLength 18: End Get 19: Set(value As Integer) 20: _sideLength = value 21: End Set 22: End Property 23: End Class   Now, say we had the following test: 1: Public Sub SetHeight_DoesNotAffectWidth(rectangle As Rectangle) 2: 'arrange 3: Dim expectedWidth = 4 4: rectangle.Width = 4 5:  6: 'act 7: rectangle.Height = 7 8:  9: 'assert 10: Assert.AreEqual(expectedWidth, rectangle.Width) 11: End Sub   If we pass in a rectangle, this test passes just fine. What if we pass in a square?   This is where we see the violation of Liskov’s Principle! A square might "IS A” to a rectangle, but we have differing expectations on how a rectangle should function than how a square should! Great expectations Here’s where we pat ourselves on the back and take a victory lap around the office and tell everyone about how we understand LSP like a boss. And all is good… until we start trying to apply it to our work. If I can’t even change functionality on a simple setter without breaking the expectations on a parent class, what can I do with subtyping? Did Liskov just tell me to never touch subtyping again? The short answer: NO, SHE DIDN’T. When I first learned LSP, and from those I’ve talked with as well, I overlooked a very important but not appropriately stressed quality of the principle: our expectations. Our inclination is to want a logical catch-all, where we can easily apply this principle and wipe our hands, drop the mic and exit stage left. That’s not the case because in every different programming scenario, our expectations of the parent class or type will be different. We have to set reasonable expectations on the behaviors that we expect out of the parent, then make sure that those expectations are met by the child. Any expectations not explicitly expected of the parent aren’t expected of the child either, and don’t register as a violation of LSP that prevents implementation. You can see the flexibility mentioned in the Wikipedia article itself: A typical example that violates LSP is a Square class that derives from a Rectangle class, assuming getter and setter methods exist for both width and height. The Square class always assumes that the width is equal with the height. If a Square object is used in a context where a Rectangle is expected, unexpected behavior may occur because the dimensions of a Square cannot (or rather should not) be modified independently. This problem cannot be easily fixed: if we can modify the setter methods in the Square class so that they preserve the Square invariant (i.e., keep the dimensions equal), then these methods will weaken (violate) the postconditions for the Rectangle setters, which state that dimensions can be modified independently. Violations of LSP, like this one, may or may not be a problem in practice, depending on the postconditions or invariants that are actually expected by the code that uses classes violating LSP. Mutability is a key issue here. If Square and Rectangle had only getter methods (i.e., they were immutable objects), then no violation of LSP could occur. What this means is that the above situation with a rectangle and a square can be acceptable if we do not have the expectation for width to leave height unaffected, or vice-versa, in our application. Conclusion – the oft forgot third wheel Liskov Substitution Principle is meant to act as a guidance and warn us against unexpected behaviors. Objects can be stateful and as a result we can end up with unexpected situations if we don’t code carefully. Specifically when subclassing, make sure that the subclass meets the expectations held to its parent. Don’t let LSP think you cannot deviate from the behaviors of the parent, but understand that LSP is meant to highlight the importance of not only the parent and the child class, but also of the expectations WE set for the parent class and the necessity of meeting those expectations in order to help prevent sticky situations.   Code examples, in both VB and C# Technorati Tags: LSV,Liskov Substitution Principle,Uncle Bob,Robert Martin,Barbara Liskov,Liskov

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  • Efficient Search function with Linq to SQL

    - by Bayonian
    Hi, I'm using VB.NET and Linq to SQL. I have a table with thousands of rows and growing. Right now I'm using .Contains() in the Where clause to perform the query. Below is my search function : Public Shared Function DemoSearchFunction(ByVal keyword As String) As DataTable Dim db As New BibleDataClassesDataContext() Dim query = From b In db.khmer_books _ From ch In db.khmer_chapters _ From v In db.testing_khmers _ Where v.t_v.Contains(keyword) And ch.kh_book_id = b.kh_b_id And v.t_chid = ch.kh_ch_id _ Select b.kh_b_id, b.kh_b_title, ch.kh_ch_id, ch.kh_ch_number, v.t_id, v.t_vn, v.t_v Dim dtDataTableOne = New DataTable("dtOne") dtDataTableOne.Columns.Add("bid", GetType(Integer)) dtDataTableOne.Columns.Add("btitle", GetType(String)) dtDataTableOne.Columns.Add("chid", GetType(Integer)) dtDataTableOne.Columns.Add("chn", GetType(Integer)) dtDataTableOne.Columns.Add("vid", GetType(Integer)) dtDataTableOne.Columns.Add("vn", GetType(Integer)) dtDataTableOne.Columns.Add("verse", GetType(String)) For Each r In query dtDataTableOne.Rows.Add(New Object() {r.kh_b_id, r.kh_b_title, r.kh_ch_id, r.kh_ch_number, r.t_id, r.t_vn, r.t_v}) Next Return dtDataTableOne End Function I would like to know other methods for doing efficient search using Linq to SQL. Thanks.

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  • Pre-allocate memory between HostApp and DLL

    - by Leo
    I have a DLL which provided a decoding function, as follows: function MyDecode (Source: PChar; SourceLen: Integer; var Dest: PChar; DestLen: Integer): Boolean; stdcall; The HostApp call "MyDecode", and transfer into the Source, SourceLen and Dest parameters, the DLL returns decoded Dest and DestLen. The problem is: The HostApp impossible to know decoded Dest length, and therefore would not know how to pre-allocated Dest's memory. I know that can split "MyDecode" into two functions: function GetDecodeLen (Source: PChar; SourceLen: Integer): Integer; stdcall; // Return the Dest's length function MyDecodeLen (Source: PChar; SourceLen: Integer; var Dest: PChar): Boolean; stdcall; But, My decoding process is very complicated, so if split into two functions will affect the efficiency. Is there a better solution?

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  • PHP Doctrine - YAML syntax help. Default value for many to many relationship?

    - by Dan
    Hi, I have the following YAML schema for organising users in Doctrine: Person: tableName: people columns: id: type: integer primary: true autoincrement: true firstname: type: string notnull: true lastname: type: string notnull: true User: inheritance: extends: Person type: column_aggregation keyField: type keyValue: 1 Userdetails: columns: person_id: type: integer primary: true password: type: string notnull: true relations: User: foreignType: one local: person_id onDelete: CASCADE onUpdate: CASCADE Group: tableName: groups columns: id: type: integer primary: true autoincrement: true name: type: string notnull: true UserGroup: columns: group_id: type: integer primary: true person_id: type: integer primary: true relations: User: foreignType: many local: person_id Group: foreignType: many Basically, any people who are users will belong to one or more groups. Is there any way to add new users to a particular group by default? Any advice appreciated. Thanks

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  • foreign key constraints on primary key columns - issues ?

    - by zzzeek
    What are the pros/cons from a performance/indexing/data management perspective of creating a one-to-one relationship between tables using the primary key on the child as foreign key, versus a pure surrogate primary key on the child? The first approach seems to reduce redundancy and nicely constrains the one-to-one implicitly, while the second approach seems to be favored by DBAs, even though it creates a second index: create table parent ( id integer primary key, data varchar(50) ) create table child ( id integer primary key references parent(id), data varchar(50) ) pure surrogate key: create table parent ( id integer primary key, data varchar(50) ) create table child ( id integer primary key, parent_id integer unique references parent(id), data varchar(50) ) the platforms of interest here are Postgresql, Microsoft SQL Server.

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  • string parse and replace in for loop

    - by reffer
    i have a string that looks like this - "1AL||9CA||34CO||196WY||..." i want to use a for loop or while loop, in which if i have an integer, it should parse this string and delete the value matching that integer. example for above string string = "1AL||9CA||34CO||196WY||..." integer = 34 for ... loop new string = "1AL||9CA||196WY||..." As you can see the integer matched the integer 34 and deleted from one delimeter "||" to th next one. how can i do this?

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  • Storm Trident 'average aggregator

    - by E Shindler
    I am a newbie to Trident and I'm looking to create an 'Average' aggregator similar to 'Sum(), but for 'Average'.The following does not work: public class Average implements CombinerAggregator<Long>.......{ public Long init(TridentTuple tuple) { (Long)tuple.getValue(0); } public Long Combine(long val1,long val2){ return val1+val2/2; } public Long zero(){ return 0L; } } It may not be exactly syntactically correct, but that's the idea. Please help if you can. Given 2 tuples with values [2,4,1] and [2,2,5] and fields 'a','b' and 'c' and doing an average on field 'b' should return '3'. I'm not entirely sure how init() and zero() work. Thank you so much for your help in advance. Eli

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  • Postgesql select from 2 tables. Joins?

    - by Daniel
    I have 2 tables that look like this: Table "public.phone_lists" Column | Type | Modifiers ----------+-------------------+-------------------------------------------------------------------- id | integer | not null default nextval(('"phone_lists_id_seq"'::text)::regclass) list_id | integer | not null sequence | integer | not null phone | character varying | name | character varying | and Table "public.email_lists" Column | Type | Modifiers ---------+-------------------+-------------------------------------------------------------------- id | integer | not null default nextval(('"email_lists_id_seq"'::text)::regclass) list_id | integer | not null email | character varying | I'm trying to get the list_id, phone, and emails out of the tables in one table. I'm looking for an output like: list_id | phone | email ---------+-------------+-------------------------------- 0 | | [email protected] 0 | | [email protected] 0 | | [email protected] 0 | | [email protected] 0 | | [email protected] 1 | 15555555555 | 1 | 15555551806 | 1 | 15555555508 | 1 | 15055555506 | 1 | 15055555558 | 1 | | [email protected] 1 | | [email protected] I've come up with select pl.list_id, pl.phone, el.email from phone_lists as pl left join email_lists as el using (list_id); but thats not quite right. Any suggestions?

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  • Generics Type issue

    - by JohnJohnGa
    ArrayList<Integer> arrI = new ArrayList<Integer>(); ArrayList arrO = arrI; // Warning /* It is ok to add a String as it is an ArrayList of Objects but the JVM will know the real type, arrO is an arrayList of Integer... */ arrO.add("Hello"); /* How I can get a String in an ArrayList<Integer> ?? Even if the compiler told me that I will get an Integer! */ System.out.println(arrI.get(0)); Anybody can explain what's happening here?

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  • Dynamic binding in C++

    - by chmike
    I'm implementing a CORBA like server. Each class has remotely callable methods and a dispatch method with two possible input, a string identifying the method or an integer which would be the index of the method in a table. A mapping of the string to the corresponding integer would be implemented by a map. The caller would send the string on the first call and get back the integer with the response so that it simply has to send the integer on subsequent calls. It is just a small optimization. The integer may be assigned dynamically on demand by the server object. The server class may be derived from another class with overridden virtual methods. What could be a simple and general way to define the method binding and the dispatch method ?

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  • How do I resolve this scope issue in VB .NET?

    - by froadie
    I have a code structure something like this: For row = 1 To numRows Dim arrayIndex As Integer = 0 For column As Integer = bucketStartColumn To bucketEndColumn ' whatever code arrayIndex = arrayIndex + 1 Next Next Dim arrayIndex As Integer = 0 For column As Integer = bucketStartColumn To bucketEndColumn ' whatever code arrayIndex = arrayIndex + 1 Next Not exactly the code, so I don't really need suggestions about refactoring, but my problem is this - with this code I get a compiler error for the first Dim arrayIndex As Integer = 0 - "Variable 'arrayIndex' hides a variable in an enclosing block." As far as I can tell, arrayIndex is local to the first for loop and shouldn't exist by the time we reach the second loop. If I try to change the second declaration of arrayIndex to arrayIndex = 0, I get the error "Name 'arrayIndex' is not declared", as I expected. So is it visible, or not? Does this have something to do with the Dim keyword? Any suggestions of how to get around this, other than naming the second index variable something else?

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  • Setting a property in XAML for a User Control

    - by Ben
    Hi, I have a user control that has a property of type Integer, that i am trying to set in the XAML Template to be that of a property within the bindingsource. If I set the property using a hard coded integer i.e. <MyControl MyIntegerProperty="3" /> This works fine, but if i try <MyControl MyIntegerProperty="{Binding MyDataContextIntegerProperty}" /> it fails. I know that the integer property on MyDataContext is returning a valid integer, and i know that this format works, as directly above this in the template, i have the line <TextBlock Text="{Binding MyDataContextStringProperty}" /> which works correctly. Is there any flag that i need to set on my User Controls Integer property to allow this to work? Or am i doing something else wrong? Thanks

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  • Why does the right-shift operator produce a zero instead of a one?

    - by mrt181
    Hi, i am teaching myself java and i work through the exercises in Thinking in Java. On page 116, exercise 11, you should right-shift an integer through all its binary positions and display each position with Integer.toBinaryString. public static void main(String[] args) { int i = 8; System.out.println(Integer.toBinaryString(i)); int maxIterations = Integer.toBinaryString(i).length(); int j; for (j = 1; j < maxIterations; j++) { i >>= 1; System.out.println(Integer.toBinaryString(i)); } In the solution guide the output looks like this: 1000 1100 1110 1111 When i run this code i get this: 1000 100 10 1 What is going on here. Are the digits cut off? I am using jdk1.6.0_20 64bit. The book uses jdk1.5 32bit.

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  • Rails has_one vs belongs_to semantics

    - by Anurag
    I have a model representing a Content item that contains some images. The number of images are fixed as these image references are very specific to the content. For example, the Content model refers to the Image model twice (profile image, and background image). I am trying to avoid a generic has_many, and sticking to multiple has_one's. The current database structure looks like: contents - id:integer - integer:profile_image_id - integer:background_image_id images - integer:id - string:filename - integer:content_id I just can't figure out how to setup the associations correctly here. The Content model could contain two belongs_to references to an Image, but that doesn't seem semantically right cause ideally an image belongs to the content, or in other words, the content has two images. This is the best I could think of (by breaking the semantics): class Content belongs_to :profile_image, :class_name => 'Image', :foreign_key => 'profile_image_id' belongs_to :background_image, :class_name => 'Image', :foreign_key => 'background_image_id' end Am I way off, and there a better way to achieve this association?

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  • Is there a good (standalone) PHPDoc parser class or function in PHP?

    - by Kris
    Hi folks, I'm looking for some method of converting a PHP Docblock (as used for generating documentation by tools like Doxygen) into a structure I can inspect in PHP. For example, I want to parse the following lines: /** * Multiply two values * @CHECKME * * @author someone * @created eons ago * * @param integer $x * @param integer $x * * @return integer */ function multiply($x, $y) { return $x * $y; } Into something similar to: array( 'author' = 'someone' ,'created' = 'eons ago' ,'param' = array( 'integer $x' ,'integer $y' ) ,'_flags' = array( '@CHECKME' ) ); I explicitly cannot use PEAR or any such library, it has to be relatively standalone. Any given solution that is better than using a bunch of regexes after stripping away comment outline would be awesome.

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  • create a model in create action from a class

    - by Pontek
    As a newbie to rails I can't find how to solve my issue ^^ I want to create a VideoPost from a form with a text field containing a video url (like youtube) I'm getting information on the video thanks to the gem https://github.com/thibaudgg/video_info And I want to save thoses information using a model of mine (VideoInformation). But I don't know how the create process should work. Thanks for any help ! I'm trying to create a VideoPost in VideoPostsController like this : def create video_info = VideoInfo.new(params[:video_url]) video_information = VideoInformation.create(video_info) #undefined method `stringify_keys' for #<Youtube:0x00000006a24120> if video_information.save @video_post = current_user.video_posts.build(video_information) end end My VideoPost model : # Table name: video_posts # # id :integer not null, primary key # user_id :integer # video_information_id :integer # created_at :datetime not null # updated_at :datetime not null My VideoInformation model (which got same attributes name than VideoInfo gem) : # Table name: video_informations # # id :integer not null, primary key # title :string(255) # description :text # keywords :text # duration :integer # video_url :string(255) # thumbnail_small :string(255) # thumbnail_large :string(255) # created_at :datetime not null # updated_at :datetime not null

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  • Rails 3: Create an instance with 3 foreign keys.

    - by donald
    Hello, Having a reviews table: # Table name: reviews # # id :integer not null, primary key # wsp_id :integer # service_id :integer # user_id :integer # description :text # rating :integer # created_at :datetime # updated_at :datetime # belongs_to :wsp belongs_to :service belongs_to :user How can I create a review for a service and pass the wsp_id and user_id? Do I need to use nested routes? I am able to do @user.reviews.new(params[:review]) but I'm not being able of passing the wsp_id and the service_id. Here's my Reviews create controller. def create @review = current_user.reviews.new(params[:review]) if @review.save #Saved else #Error, not saved end end What am I doing wrong? Thank you!

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  • Efficient implementation of exclusive execution

    - by n0weak
    I have an ObjectManager class that is used to process payments. It is wrapped over the Order entities, so new instance has to be created when processing is required. I need to prevent the situation when several ObjectManager instances are dealing with the same order simultaneously (it happend once because of some errors on the remote payment processing center, somehow they called our callback urls twice). I'd love to get an advice how to implement it more efficiently. For now, I am thinking about something like that: public class OrderManager{ private static final CopyOnWriteArrayList<Integer> LOCKER = new CopyOnWriteArrayList<Integer>(); private static synchronized boolean tryLock(Integer key) { return LOCKER.addIfAbsent(key); } private static void releaseLock(Integer key) { LOCKER.remove(key); } public void processPayment(Integer orderId) throws Exception{ if (!tryLock(orderId)) { return; } try { //operate } finally { releaseLock(orderId); } } //remainder omitted }

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