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  • Where should I initialize variables for an OO Recursive Descent Parse Tree?

    - by Vasto
    I'd like to preface this by stating that this is for a class, so please don't solve this for me. One of my labs for my cse class is creating an interpreter for a BNF that was provided. I understand most of the concepts, but I'm trying to build up my tree and I'm unsure where to initialize values. I've tried in both the constructor, and in the methods but Eclipse's debugger still only shows the left branch, even though it runs through completely. Here is my main procedure so you can get an idea of how I'm calling the methods. public class Parser { public static void main(String[] args) throws IOException { FileTokenizer instance = FileTokenizer.Instance(); FileTokenizer.main(args); Prog prog = new Prog(); prog.ParseProg(); prog.PrintProg(); prog.ExecProg(); } Now here is My Prog class: public class Prog { private DeclSeq ds; private StmtSeq ss; Prog() { ds = new DeclSeq(); ss = new StmtSeq(); } public void ParseProg() { FileTokenizer instance = FileTokenizer.Instance(); instance.skipToken(); //Skips program (1) // ds = new DeclSeq(); ds.ParseDS(); instance.skipToken(); //Skips begin (2) // ss = new StmtSeq(); ss.ParseSS(); instance.skipToken(); } I've tried having Prog() { ds = null; ss = null; } public void ParseProg() { FileTokenizer instance = FileTokenizer.Instance(); instance.skipToken(); //Skips program (1) ds = new DeclSeq(); ds.ParseDS(); ... But it gave me the same error. I need the parse tree built up so I can do a pretty print and an execute command, but like I said, I only get the left branch. Any help would be appreciated. Explanations why are even more so appreciated. Thank you, Vasto

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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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  • How to schedule an alarm so that the intent is broadcast everytime the date changes?

    - by rogerstone
    I want to schedule an alarm which throws an intent when the date changes. I know that this would do this the job alarms.setRepeating(AlarmManager.RTC_WAKEUP,triggerAtTime, interval,alarmIntent); But what is confusing me is what to put in the triggerAtTime and the interval.It says System.currentTimeMillis() timebase. I might be installing the app on any day so the TriggerAtTime should be midnight of that day and the interval would be 24 hours from there on. How can I acheive this.Can someone tell me what to put in TriggerAtTime and interval in the required format. Thanks

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  • Hibernate/JPA - annotating bean methods vs fields

    - by Benju
    I have a simple question about usage of Hibernate. I keep seeing people using JPA annotations in one of two ways by annotating the fields of a class and also by annotating the get method on the corresponding beans. My question is as follows: Is there a difference between annotating fields and bean methods with JPA annoations such as @Id. example: @Entity public class User { **@ID** private int id; public int getId(){ return this.id; } public void setId(int id){ this.id=id; } } -----------OR----------- @Entity public class User { private int id; **@ID** public int getId(){ return this.id; } public void setId(int id){ this.id=id; } }

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  • Spring @Autowired messageSource working in Controller but not in other classes?

    - by Jayaprakash
    New updates: As I could not succeed in configuring messageSource through annotations, I attempted to configure messageSource injection through servlet-context.xml. I still have messageSource as null. Please let me know if you need any more specific info, and I will provide. Thanks for your help in advance. servlet-context.xml <beans:bean id="message" class="com.mycompany.myapp.domain.common.message.Message"> <beans:property name="messageSource" ref="messageSource" /> </beans:bean> Spring gives the below information message about spring initialization. INFO : org.springframework.context.annotation.ClassPathBeanDefinitionScanner - JSR-330 'javax.inject.Named' annotation found and supported for component scanning INFO : org.springframework.beans.factory.support.DefaultListableBeanFactory - Overriding bean definition for bean 'message': replacing [Generic bean: class [com.mycompany.myapp.domain.common.message.Message]; scope=singleton; abstract=false; lazyInit=false; autowireMode=0; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=null; factoryMethodName=null; initMethodName=null; destroyMethodName=null; defined in file [C:\springsource\tc-server-developer-2.1.0.RELEASE\spring-insight-instance\wtpwebapps\myapp\WEB-INF\classes\com\mycompany\myapp\domain\common\message\Message.class]] with [Generic bean: class [com.mycompany.myapp.domain.common.message.Message]; scope=; abstract=false; lazyInit=false; autowireMode=0; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=null; factoryMethodName=null; initMethodName=null; destroyMethodName=null; defined in ServletContext resource [/WEB-INF/spring/appServlet/servlet-context.xml]] INFO : org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor - JSR-330 'javax.inject.Inject' annotation found and supported for autowiring INFO : org.springframework.beans.factory.support.DefaultListableBeanFactory - Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@1c7caac5: defining beans [org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping#0,org.springframework.format.support.FormattingConversionServiceFactoryBean#0,org.springframework.validation.beanvalidation.LocalValidatorFactoryBean#0,org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter#0,org.springframework.web.servlet.handler.MappedInterceptor#0,org.springframework.web.servlet.mvc.HttpRequestHandlerAdapter,org.springframework.web.servlet.resource.ResourceHttpRequestHandler#0,org.springframework.web.servlet.handler.SimpleUrlHandlerMapping#0,xxxDao,message,xxxService,jsonDateSerializer,xxxController,homeController,org.springframework.context.annotation.internalConfigurationAnnotationProcessor,org.springframework.context.annotation.internalAutowiredAnnotationProcessor,org.springframework.context.annotation.internalRequiredAnnotationProcessor,org.springframework.context.annotation.internalCommonAnnotationProcessor,tilesViewResolver,tilesConfigurer,messageSource,org.springframework.web.servlet.handler.MappedInterceptor#1,localeResolver,org.springframework.web.servlet.view.ContentNegotiatingViewResolver#0,validator,resourceBundleLocator,messageInterpolator]; parent: org.springframework.beans.factory.support.DefaultListableBeanFactory@4f47af3 I have the below definition for message source in 3 classes. In debug mode, I can see that in class xxxController, messageSource is initialized to org.springframework.context.support.ReloadableResourceBundleMessageSource. I have annotated Message class with @Component and xxxHibernateDaoImpl with @Repository. I also included context namespace definition in servlet-context.xml. But in Message class and xxxHibernateDaoImpl class, the messageSource is still null. Why is Spring not initializing messageSource in the two other classes though in xxxController classes, it initializes correctly? @Controller public class xxxController{ @Autowired private ReloadableResourceBundleMessageSource messageSource; } @Component public class Message{ @Autowired private ReloadableResourceBundleMessageSource messageSource; } @Repository("xxxDao") public class xxxHibernateDaoImpl{ @Autowired private ReloadableResourceBundleMessageSource messageSource; } <beans:beans xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation=" http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd"> <beans:bean id="messageSource" class="org.springframework.context.support.ReloadableResourceBundleMessageSource"> <beans:property name="basename" value="/resources/messages/messages" /> </beans:bean> <context:component-scan base-package="com.mycompany.myapp"/> </beans>

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  • Configure autocomplete in intellij with hamcrest and mockito dsl

    - by sgargan
    I'm wondering if its possible to configure Intellij's smart insert to suggest hamcrest and mockito dsl idioms when in test classes. Really I'm looking for something like eclipse's 'static favorites', so that when I hit ctrl + space or ctrl +shift +space the idioms are present. In general is it possible to configure autocomplete/smart insert or the suggestions balloon for that matter. I've looked through the settings without much luck but could easily have overlooked something.

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  • Hibernate session method to update object

    - by EugeneP
    I need this roadmap of a Hibernate managed object instance. First, I create an instance with initial properties and persist this object in a db. Then session associated with this object is closed. But still, I serialize my object and on the next step deserialize it, invoke some setters, and again, I need to update what changed in a database. What methods of Hibernate session should I use? persist() or save() on the first step and saveOrUpdate() on the second? In fact I see that saveOrUpdate() can be used on each step. What would you recommend?

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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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  • Remove then Query fails in JPA/Hibernate (deleted entity passed to persist)

    - by Kevin
    I've got a problem with the removal of entities in my JPA application: basically, I do in this EJB Business method: load photo list ; for each photo { //UPDATE remove TagPhoto element from @OneToMany relation //DISPLAY create query involving TagPhoto ... } and this last query always throws an EntityNotFoundException (deleted entity passed to persist: [...TagPhoto#]) I think I understand the meaning of this exception, like a synchronization problem caused by my Remove, but how can I get rid of it?

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  • Seam @Factory in abstract base class?

    - by Shadowman
    I've got a series of web actions I'm implementing in Seam to perform create, read, update, etc. operations. For my read/update/delete actions, I'd like to have individual action classes that all extend an abstract base class. I'd like to put the @Factory method in the abstract base class to retrieve the item that is to be acted upon. For example, I have this as the base class: public abstract class BaseAction { @In(required=false)@Out(required=false) private MyItem item=null; public MyItem getItem(){...} public void setItem(...){...} @Factory("item") public void initItem(){...} } My subclasses would extend BaseAction, so that I don't have to repeat the logic to load the item that is to be viewed, deleted, updated, etc. However, when I start my application, Seam throws errors saying I have declared multiple @Factory's for the same object. Is there any way around this? Is there any way to provide the @Factory in the base class without encoutnering these errors?

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  • ScheduledExecutorService throwable lost

    - by Andrey
    Hello, Consider I scheduled a Runnable for periodic execution with ScheduledExecutorService and there occurs some system Error like OutOfMemory. It will be silently swallowed. scheduler.scheduleWithFixedDelay(new Runnable() { @Override public void run() { throw new OutOfMemoryError(); // Swallowed } }, 0, delay, TimeUnit.SECONDS); Is it normal? Why doesn't it propagate to the container? What is the correct way to handle such errors? Thanks!

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  • How to Deploy my Open Source Projects using Maven's Central Repository?

    - by sfussenegger
    Is there anything I could do to get my own open source stuff into Maven's Central repository? I've wondered many times how I could get my own projects into Maven's Central repository. I was asking this myself, especially as I've seen some well known projects hosting their own repository, requiring users to add dependency and repository. At the same time, it's getting difficult for other projects to depend on those projects. As I neither want others to add an additional repository nor to host one myself, I'm looking for other ways. And why aren't some projects using the option to deploy to Maven Central in favor of their self-hosted repository? Any good reasons that aren't obvious?

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  • How to disable expand sign in Swing JTree?

    - by user2899630
    I'm working in Swing and I would like to disable the expand (plus [+]) sign on a certain type of nodes. Not sure how to do it because my nodes aren't leaves and I also cannot use setShowsRootHandles (which is only for the root). I'm referring to to JTree: suppose i got this structure: Root --[+] node1 --[+] node2 when I load this structure i would like not to see the [+] sign on node2 (because it a special type node). But I also would like to expand it by using a special command. I've overridden isLeaf() (method from DefaultMutableTreeNode) so it would set to to TRUE when i'm in the special type node, but then when I'm trying to expand it, it wouldn't expand because isLeaf() == TRUE... Hope this will make things more clear.

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  • Androids ExpandableListView - where to put the button listener for buttons that are children

    - by CommonKnowledge
    I have been playing around a lot with the ExpandableListView and I cannot figure out where to add the button listeners for the button that will be the children in the view. I did manage to get a button listener working that uses getChildView() below, but it seems to be the same listener for all the buttons. The best case scenario is that I would be able to implement the button listeners in the class that instantiates the ExpandableListAdapter class, and not have to put the listeners in the actual ExpandableListAdapter class. At this point I don't even know if that is possible I have been experimenting with this tutorial/code: HERE getChildView() @Override public View getChildView(int set_new, int child_position, boolean view, View view1, ViewGroup view_group1) { ChildHolder childHolder; if (view1 == null) { view1 = LayoutInflater.from(info_context).inflate(R.layout.list_group_item_lv, null); childHolder = new ChildHolder(); childHolder.section_btn = (Button)view1.findViewById(R.id.item_title); view1.setTag(childHolder); childHolder.section_btn.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { Toast.makeText(info_context, "button pushed", Toast.LENGTH_SHORT).show(); } }); }else { childHolder = (ChildHolder) view1.getTag(); } childHolder.section_btn.setText(children_collection.get(set_new).GroupItemCollection.get(child_position).section); Typeface tf = Typeface.createFromAsset(info_context.getAssets(), "fonts/AGENCYR.TTF"); childHolder.section_btn.setTypeface(tf); return view1; } Any help would be much appreciated. Thank you and I will be standing by.

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  • how to Solve the "Digg" problem in MongoDB

    - by user193116
    A while back,a Digg developer had posted this blog ,"http://about.digg.com/blog/looking-future-cassandra", where the he described one of the issues that were not optimally solved in MySQL. This was cited as one of the reasons for their move to Cassandra. I have been playing with MongoDB and I would like to understand how to implement the MongoDB collections for this problem From the article, the schema for this information in MySQL : CREATE TABLE Diggs ( id INT(11), itemid INT(11), userid INT(11), digdate DATETIME, PRIMARY KEY (id), KEY user (userid), KEY item (itemid) ) ENGINE=InnoDB DEFAULT CHARSET=utf8; CREATE TABLE Friends ( id INT(10) AUTO_INCREMENT, userid INT(10), username VARCHAR(15), friendid INT(10), friendname VARCHAR(15), mutual TINYINT(1), date_created DATETIME, PRIMARY KEY (id), UNIQUE KEY Friend_unique (userid,friendid), KEY Friend_friend (friendid) ) ENGINE=InnoDB DEFAULT CHARSET=utf8; This problem is ubiquitous in social networking scenario implementation. People befriend a lot of people and they in turn digg a lot of things. Quickly showing a user what his/her friends are up to is very critical. I understand that several blogs have since then provided a pure RDBMs solution with indexes for this issue; however I am curious as to how this could be solved in MongoDB.

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  • list or container O(1)-ish insertion/deletion performance, with array semantics

    - by Chris Kaminski
    I'm looking for a collection that offers list semantics, but also allows array semantics. Say I have a list with the following items: apple orange carrot pear then my container array would: container[0] == apple container[1] == orangle container[2] == carrot Then say I delete the orange element: container[0] == apple container[1] == carrot I don't particularly care if sort order is maintained, I'd just like the array values to function as accelerators to the list items, and I want to collapse gaps in the array without having to do an explicit resizing.

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  • Can I assign a maven dependency to a specific repo?

    - by mds
    So I have several large projects that use up to 8 different external repos, all specified in settings.xml rather than in poms. A lot of our internal dependencies are snapshots, so this obviously causes a lot of checking for updates across several external repos, when they are all in our internal repo. So my question is, is there a way to setup a profile/filter or anything similar where I can ensure that an update will only be checked for in a specific repo(s)? This is all in the spirit of better/quicker builds. Thanks!

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  • Is context:annotation-config an alternative to @AutoWired?

    - by Antacid
    Is it correct that I can put context:annotation-config in my XML config and it will automatically inject the bean class without needing any annotations? So instead of using these annotation types: public class Mailman { private String name; @Autowired private Parcel Parcel; public Mailman(String name) { this.name = name; } @Autowired public void setParcel(Parcel Parcel) { this.Parcel = Parcel; } @Autowired public void directionsToParcel(Parcel Parcel) { this.Parcel = Parcel; } } I would just need to write this: <beans ... > <bean id="mailMan" class="MailMan"> <constructor-arg value="John Doe"/> </bean> <bean id="parcel" class="Parcel" /> <context:annotation-config /> </beans> and then my MailMan class would look a lot simpler without the need for annotations: public class Mailman { private String name; private Parcel Parcel; public Mailman(String name) { this.name = name; } }

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