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• NullPointerException when setting adapter

  - by Sorin Grecu

  I'm trying to get the filenames in a folder inside a listview(that listview is inside a layout of a ViewPager) but i'm getting a NullPointerException and i can't figure what's wrong. public void citire() { ListView lv1 = (ListView) findViewById(R.id.lv1); myList = new ArrayList<String>(); File directory = Environment.getExternalStorageDirectory(); file = new File(directory + "/InterSRL"); File list[] = file.listFiles(); for (int i = 0; i < list.length; i++) { myList.add(list[i].getName()); } ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, android.R.id.text1, myList); lv1.setAdapter(adapter); } I'm getting the error at lv1.setAdapter(adapter); 06-28 13:10:57.987: E/AndroidRuntime(30450): Caused by: java.lang.NullPointerException 06-28 13:10:57.987: E/AndroidRuntime(30450): at com.example.testlayout.Gestionare.citire(Gestionare.java:169) 06-28 13:10:57.987: E/AndroidRuntime(30450): at com.example.testlayout.Gestionare.onCreate(Gestionare.java:33) 06-28 13:10:57.987: E/AndroidRuntime(30450): at android.app.Activity.performCreate(Activity.java:5104) 06-28 13:10:57.987: E/AndroidRuntime(30450): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080) 06-28 13:10:57.987: E/AndroidRuntime(30450): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)

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• Strange behavior while returning csv file from spring controller

  - by Fanooos

  I working in a spring application which have an action method that returns a CSV file. This action works fine but in some cases it throws a predefined exception (MyAppException). I have another method that is annotated @ExceptionHandler(MyAppException.class) In the exception handler method I return another csv file but with different contents. The code that returns the csv file is almost the same in the two methods. List<String[]> list= new ArrayList<String[]>(); list.add(new String[]{ integrationRequestErrorLog.getErrorMessage(), Long.toString(integrationRequestErrorLog.getId()), Integer.toString(integrationRequestErrorLog.getErrorCode()) }); CSVWriter writer = new CSVWriter(response.getWriter(), ','); writer.writeAll(list); writer.close(); the difference between the two method is the list of contents. In the first method the file is returned normally while in the exception handler method I have a strange behavior. The exception handler method works fine with Opera browser while it gives me a 404 with FireFox. Opera browser give me 404 also but it download the file while firefox does not? Really I do not understand what is the difference here.

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• Loading child entities with JPA on Google App Engine

  - by Phil H

  I am not able to get child entities to load once they are persisted on Google App Engine. I am certain that they are saving because I can see them in the datastore. For example if I have the following two entities. public class Parent implements Serializable{ @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Extension(vendorName="datanucleus", key="gae.encoded-pk", value="true") private String key; @OneToMany(cascade=CascadeType.ALL) private List<Child> children = new ArrayList<Child>(); //getters and setters } public class Child implements Serializable{ @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Extension(vendorName="datanucleus", key="gae.encoded-pk", value="true") private String key; private String name; @ManyToOne private Parent parent; //getters and setters } I can save the parent and a child just fine using the following: Parent parent = new Parent(); Child child = new Child(); child.setName("Child Object"); parent.getChildren().add(child); em.persist(parent); However when I try to load the parent and then try to access the children (I know GAE lazy loads) I do not get the child records. //parent already successfully loaded parent.getChildren.size(); // this returns 0 I've looked at tutorial after tutorial and nothing has worked so far. I'm using version 1.3.3.1 of the SDK. I've seen the problem mentioned on various blogs and even the App Engine forums but the answer is always JDO related. Am I doing something wrong or has anyone else had this problem and solved it for JPA?

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• Database insertion not happening

  - by Pramod Setlur

  int i=0; ContentValues values = null; for ( SortedMap.Entry<Integer, String> entry : mapDefect.entrySet() ) { if( i++ < count ) continue; if( i < arrlst.size() ) { values = new ContentValues(); Log.d("MAP", "Id :"+entry.getKey()+"Des :"+entry.getValue()+"Co :"+ arrlst.get(i)); values.put( MARKER_COORD, arrlst.get( i ) ); values.put( MARKER_ID, entry.getKey() ); values.put( DEFECT_DESCRIPTION, entry.getValue() ); values.put( IMAGE_ID_F, imageID + 1 ); Log.d( "Err", "in insertNewDefectsDescription" ); long rowId = db.insert( TABLE_DEFECTS, null, values ); long rowId1 = rowId; i++; } } So, I want to access the arraylist only after the count variable, which is why the:- if(i++<count) continue; But, when I insert a break point at the 'insert' line, it is not working. The line is not executing at all, and hence the data is not being inserted into the database. What has gone wrong?? The 'values' are null.

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• StoreFilterField input doesn't react

  - by user1289877

  I'm trying to build grid with build in column filtering (using sencha gxt), here is my code: public Grid<Stock> createGrid() { // Columns definition ColumnConfig<Stock, String> nameCol = new ColumnConfig<Stock, String>(props.name(), 100, "Company"); // Column model definition and creation List<ColumnConfig<Stock, ?>> cl = new ArrayList<ColumnConfig<Stock, ?>>(); cl.add(nameCol); ColumnModel<Stock> cm = new ColumnModel<Stock>(cl); // Data populating ListStore<Stock> store = new ListStore<Stock>(props.key()); store.addAll(TestData.getStocks()); // Grid creation with data final Grid<Stock> grid = new Grid<Stock>(store, cm); grid.getView().setAutoExpandColumn(nameCol); grid.setBorders(false); grid.getView().setStripeRows(true); grid.getView().setColumnLines(true); // Filters definition StoreFilterField<Stock> filter = new StoreFilterField<Stock>() { @Override protected boolean doSelect(Store<Stock> store, Stock parent, Stock item, String filter) { // Window.alert(String.valueOf("a")); String name = item.getName(); name = name.toLowerCase(); if (name.startsWith(filter.toLowerCase())) { return true; } return false; } }; filter.bind(store); cm.addHeaderGroup(0, 0, new HeaderGroupConfig(filter, 1, 1)); filter.focus(); return grid; } My problem is: after I run this code, I cannot write anything to filter input, I'm using test data and classes (Stock.java and StockProperties.java) from this example: http://sencha.com/examples-dev/#ExamplePlace:filtergrid I try to put allert in doSelect method to check if this function was called, but it wasn't. Any idea will be welcome. Thanks.

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• Finding duplicates in a list using recursion?

  - by user1760892

  I'm suppose to find if there is duplicates in a list and return true or false using recursion only (no loops). So if ArrayList of char is used, [a,b,c,d,e] should return false. [a,a,b,c,d] or [a,b,b,c,c,d] should return true. I've tried and tested different ways and it worked for some cases but not all. I changed my code around and this is what I have now. (Has problem at the last if statement) Can anyone give me some hints? Thanks. public static <T> boolean duplicate(List<T> list) throws NullPointerException { return duplicateHelper(list, list.get(0)); } public static <T> boolean duplicateHelper(List<T> list, T t){ if (list == null) throw new NullPointerException(); if(list.isEmpty()) return false; if(list.size() > 1){ if(t.equals(list.get(1))) return true; } if(list.size() == 1) return false; if(!duplicateHelper(list.subList(1,list.size()), t)){ return duplicate(list.subList(1,list.size())); } return false; }

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• Java NullPointerException In the constructor's class

  - by AndreaF

  I have made a Java class where I have defined a constructor and some methods but I get a NullPointer Exception, and I don't know how I could fix It. public class Job { String idJob; int time; int timeRun; Job j1; List<Job> startBeforeStart; List<Job> restricted; Job(String idJob, int time){ this.idJob=idJob; this.time=time; } public boolean isRestricted() { return restricted.size() != 0; } public void startsBeforeStartOf(Job job){ startBeforeStart.add(job); job.restricted.add(this); } public void startsAfterStartOf(Job job){ job.startsBeforeStartOf(this); } public void checkRestrictions(){ if (!isRestricted()){ System.out.println("+\n"); } else{ Iterator<Job> itR = restricted.iterator(); while(itR.hasNext()){ Job j1 = itR.next(); if(time>timeRun){ System.out.println("-\n"); time--; } else { restricted.remove(j1); } } } } @Override public boolean equals(Object obj) { return obj instanceof Job && ((Job) obj).idJob.equals(idJob); } public void run() { timeRun++; } } PS Looking in a forum a user says that to fix the error I should make an ArrayList inside the constructor (without modify the received parameters that should remain String id and int time), but I haven't understand what He mean.

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• onItemClick gives index/ position of item on visible page ... not actual index of the item in list .

  - by Abhinav

  hi, I am creating a list .. the elements of the list are drawn from sqlite database .. I populate the list using ArrayList and ArrayAdapter ...upon clicking the items on the list I want to be able to fire an intent containing info about the item clicked ... info like the index number of the item .. using the method : onItemClick(AdapterView av, View v, int index, long arg) I do get index of the item clicked . however it is of the list currently displayed . the problem comes when I do setFilterTextEnabled(true) , and on the app type in some text to to search some item ..and then click it ..rather than giving me the index of the item on the original list it gives me the index on filtered list.. following is the snippet of code: myListView.setOnItemClickListener(new OnItemClickListener() { public void onItemClick(AdapterView<?> av, View v, int index, long arg) { Intent lyricsViewIntent = new Intent(iginga.this, LyricsPage.class); lyricsViewIntent.putExtra("title", songList.get((int)arg).getTitle()); lyricsViewIntent.putExtra("id", songList.get((int)arg).getSongId()); startActivity(lyricsViewIntent); } }); myListView.setTextFilterEnabled(true); Is there any way I can get the original index /position of the item instead of the one showing in filtered text ...when filtered.

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• Multiple Exception Handling in one if statement [closed]

  - by JA3N

  I am having trouble with throwing and catching exceptions. Here is the code for assignSeat(), assignSeat is called in a try block in another class. void assignSeat(String passengerName, int x, int y) throws SeatOccupiedException, InvalidPassengerNameException { Seat tSeat = airplane.getSeat(x,y); if (tSeat!=null) { if (passengerName.isEmpty() || !passengerName.matches("[a-zA-Z]+")) { throw new InvalidPassengerNameException(); } //excluded else if else if (foundPassenger(passengerName)) { airplane.seatList.get(airplane.seatNumber(passengerName)).unOccupy(); tSeat.occupy(); for (int i = 0; i<passengers.size();i++) if (passengers.get(i).getName().equals(passengerName)) passengers.get(i).changeSeat(tSeat.getSeatName()); } else if (!tSeat.occupied) { tSeat.occupy(); addPassenger(passengerName, tSeat.getSeatName()); } else if (tSeat.occupied) { throw new SeatOccupiedException(); } } and here is the code that calls assignSeat() and is in another class (I won't copy the whole class to make it look clearer) if (afComp.currentAF != null) { try { afComp.currentAF.assignSeat(nameField.getText(), x, y); //<-Problem here, "Unhandled exception type SeatOccupiedException" } catch (SeatOccupiedException exception) //<-Problem here, "Unreachable catch block, This exception is never thrown from the try statement body" { } catch(InvalidPassengerNameException exception) //<-No problems. { } } Whats wrong with the try block? why won't it throw the SeatOccupiedException? Exception classes: SeatOccupied: package a2; public class SeatOccupiedException extends Exception { public SeatOccupiedException(){} } InvalidPassengerName: package a2; public class InvalidPassengerNameException extends Exception { public InvalidPassengerNameException() {} } Every class I have is in package a2 imports for class that calls assignSeat package a2; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.MouseListener; import java.awt.event.MouseMotionListener; import java.awt.event.MouseEvent; import java.awt.BorderLayout; import javax.swing.*; import javax.swing.event.*; imports for class that has assignSeat package a2; import java.util.ArrayList;

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• how to query an embedded entity by using a query builder

  - by user577719

  I've searched quite a time for an answer to this question. Following Codesmell: @Entity public class Person { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) protected Integer id; @Column(nullable = true, length = 50) @Size(max = 50) private String name; @Embedded @Valid protected Adress adress; public void setId(Integer id) { this.id = id; } public Integer getId() { return this.id; } public void setName(String name) { this.name = name; } public void getName() { return this.name; } public void setAdress(Adress adress) { this.adress = adress; } public void getAdress() { return this.adress; } } @Embeddable public class Adress { @Column(nullable = false, length = 50) @Size(max = 50) @NotNull private String place; public void setPlace(String place) { this.place = place; } public void getPlace() { return this.place; } } public class PersonDaoJpa { public List<Ort> findByPerson(final Person person) { CriteriaBuilder builder = this.entityManager.getCriteriaBuilder(); CriteriaQuery<Person> query = builder.createQuery(Person.class); Root<Person> rootPerson = query.from(Person.class); List<Predicate> wherePredicates = new ArrayList<Predicate>(); if (person.getName() != null) { wherePredicates.add( builder.like(builder.lower(rootPerson.<String>get("name")), ort.getName().toLowerCase()) ); } Adresse adresse = ort.getAdresse(); if (adresse != null) { if(adresse.getPlace() != null) { // this won't work wherePredicates.add( builder.like(builder.lower(rootPerson.<String>get("person.adress.place")), adresse.getPlace().toLowerCase()) ); } } Predicate whereClause = builder.and(wherePredicates.toArray(new Predicate[0])); query.where(whereClause); return this.entityManager.createQuery(query).getResultList(); } } How can I access the Adress.place through rootPerson? rootPerson.get("place"), or rootPerson.get("adress.place") won't work...

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• Android CursorAdapters, ListViews and background threads

  - by MattC

  This application I've been working on has databases with multiple megabytes of data to sift through. A lot of the activities are just ListViews descending through various levels of data within the databases until we reach "documents", which is just HTML to be pulled from the DB(s) and displayed on the phone. The issue I am having is that some of these activities need to have the ability to search through the databases by capturing keystrokes and re-running the query with a "like %blah%" in it. This works reasonably quickly except when the user is first loading the data and when the user first enters a keystroke. I am using a ResourceCursorAdapter and I am generating the cursor in a background thread, but in order to do a listAdapter.changeCursor(), I have to use a Handler to post it to the main UI thread. This particular call is then freezing the UI thread just long enough to bring up the dreaded ANR dialog. I'm curious how I can offload this to a background thread totally so the user interface remains responsive and we don't have ANR dialogs popping up. Just for full disclosure, I was originally returning an ArrayList of custom model objects and using an ArrayAdapter, but (understandably) the customer pointed out it was bad memory-manangement and I wasn't happy with the performance anyways. I'd really like to avoid a solution where I'm generating huge lists of objects and then doing a listAdapter.notifyDataSetChanged/Invalidated() Here is the code in question: private Runnable filterDrugListRunnable = new Runnable() { public void run() { if (filterLock.tryLock() == false) return; cur = ActivityUtils.getIndexItemCursor(DrugListActivity.this); if (cur == null || forceRefresh == true) { cur = docDb.getItemCursor(selectedIndex.getIndexId(), filter); ActivityUtils.setIndexItemCursor(DrugListActivity.this, cur); forceRefresh = false; } updateHandler.post(new Runnable() { public void run() { listAdapter.changeCursor(cur); } }); filterLock.unlock(); updateHandler.post(hideProgressRunnable); updateHandler.post(updateListRunnable); } };

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• Can anyone help why my mockery doesn't work?

  - by user509550

  The test call real method(service) without mocking some expecations @Test public void testPropertyList() { Credentials creds = new Credentials(); creds.setUsername("someEmail"); creds.setPassword("somePassword"); creds.setReferrer("someReferrer"); final Collection<PropertyInfo> propertyInfoCollection = new LinkedList<PropertyInfo>(); final List<ListingInfo> listings = new ArrayList<ListingInfo>(); listings.add(listingInfoMock); listings.add(listingInfoMock); propertyInfoCollection.add(new PropertyInfo("c521bf5796274bd587c00bec80583c00", listings)); MultivaluedMap<String, String> params = new MultivaluedMapImpl(); params.add("page", "5"); params.add("size", "5"); instance.setPropertyListFacade(propertyListFacadeMock); mockery.checking(new Expectations() { { one(propertyListFacadeMock).getUserProperties(); will(returnValue(propertyInfoCollection)); one(listingInfoMock).getPropertyName(); allowing(listingInfoMock).getThumbnailURL(); one(listingInfoMock).getListingSystemId(); one(listingInfoMock).getPropertyURL(); one(listingInfoMock).getListingSystemId(); one(listingInfoMock).getPropertyURL(); } }); instance.setSessionManager(dashboardSessionManagerMock); testSuccessfulAuthenticate(); ClientResponse response = resource.path(PROPERTIES_PATH).queryParams(params).accept(MediaType.APPLICATION_XML) .get(ClientResponse.class); assertEquals(200, response.getStatus()); mockery.assertIsSatisfied(); }

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• Help! I'm a Haskell Newbie

  - by Darknight

  I've only just dipped my toe in the world of Haskell as part of my journey of programming enlightenment (moving on from, procedural to OOP to concurrent to now functional). I've been trying an online Haskell Evaluator. However I'm now stuck on a problem: Create a simple function that gives the total sum of an array of numbers. In a procedural language this for me is easy enough (using recursion) (c#) : private int sum(ArrayList x, int i) { if (!(x.Count < i + 1)) { int t = 0; t = x.Item(i); t = sum(x, i + 1) + t; return t; } } All very fine however my failed attempt at Haskell was thus: let sum x = x+sum in map sum [1..10] this resulted in the following error (from that above mentioned website): Occurs check: cannot construct the infinite type: a = a -> t Please bear in mind I've only used Haskell for the last 30 minutes! I'm not looking simply for an answer but a more explanation of it. Thanks in advanced.

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• Google App Engine error Object Manager has been closed

  - by newbie

  I had following error from Google App Engine when I was trying to iterate list in JSP page with EL. Object Manager has been closed I solved problem with following coe, but I don't think that it is very good solution to this problem: public List<Item> getItems() { PersistenceManager pm = getPersistenceManager(); Query query = pm.newQuery("select from " + Item.class.getName()); List<Item> items = (List<Items>) query.execute(); List<Item> items2 = new ArrayList<Item>(); // This line solved my problem Collections.copy(items, items2); // and this also pm.close(); return (List<Item>) items; } When I tried to use pm.detachCopyAll(items) it gave same error. I understood that detachCopyAll() method should do same what I did, but that method should be part of data nucelus, so it should be used instead of my owm methods. So why dosen't detachCopyAll() work at all?

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• Java/Android get array from xml

  - by Ashley

  I have a list of longitude and longitude points in an xml file that is used throughout my application. I find my self repeating this code to get points often and think there must be a better way? String[] mTempArray = getResources().getStringArray(R.array.stations); int len = mTempArray.length; mStationArray = new ArrayList<Station>(); for(int i = 0; i < len; i++){ Station s = new Station(); String[] fields = mTempArray[i].split("[\t ]"); s.setValuesFromArray(fields); Log.i("ADD STATION", ""+s); mStationArray.add(s); } XML is in the format of: <?xml version="1.0" encoding="utf-8"?> <resources> <array name="stations"> <item> <name>Station name</name> <longitude>1111111</longitude> <latitude>11111</latitude> <code>1</code> </item> And another (possible) problem is that to get just one station I have to get all of them and pull the one I want from the array. Is this going to be considerably slower? Can I make this array consistent throughout the app? (But keeping the separate Intent methodology)

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• Handling very large lists of objects without paging?

  - by user246114

  Hi, I have a class which can contain many small elements in a list. Looks like: public class Farm { private ArrayList<Horse> mHorses; } just wondering what will happen if the mHorses array grew to something crazy like 15,000 elements. I'm assuming that trying to write and read this from the datastore would be crazy, because I'd get killed on the serialization process. It's important that I can get the entire array in one shot without paging, and each Horse element may only have two string properties in it, so they are pretty lightweight: public class Horse { private String mId; private String mName; } I don't need these horses indexed at all. Does it sound reasonable to just store the mHorse array as a raw Text field, and force my clients to do the deserialization? Something like: public class Farm { private Text mHorsesSerialized; } then whenever the client receives a Farm instance, it has to take the raw string of horses, and split it in order to reinstantiate the list, something like: // GWT client perhaps Farm farm = rpcCall.getMyFarm(); String horsesSerialized = farm.getHorses(); String[] horseBlocks = horsesSerialized.split(","); for (int i = 0; i < horseBlocks.length; i++) { // .. continue deserializing the individual objects ... } yeah... so hopefully it would be quick to read a Farm instance from the datastore, and the serialization penalty is paid by the client, Thanks

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• Hibernate HQL m:n join problem

  - by smallufo

  I am very unfamiliar with SQL/HQL , and am currently stuck with this 'maybe' simple problem : I have two many-to-many Entities , with a relation table : Car , CarProblem , and Problem . One Car may have many Problems , One Problem may appear in many Cars, CarProblem is the association table with other properties . Now , I want to find Car(s) with specified Problem , how do I write such HQL ? All ids are Long type . I've tried a lot of join / inner-join combinations , but all in vain.. -- updated : Sorry , forget to mention : Car has many CarProblem Problem has many CarProblem Car and Problem are not directly connected in Java Object. -- update , java code below -- @Entity public class Car extends Model{ @OneToMany(mappedBy="car" , cascade=CascadeType.ALL) public Set<CarProblem> carProblems; } @Entity public class CarProblem extends Model{ @ManyToOne public Car car; @ManyToOne public Problem problem; ... other properties } @Entity public class Problem extends Model { other properties ... // not link to CarProblem , It seems not related to this problem // **This is a very stupid query , I want to get rid of it ...** public List<Car> findCars() { List<CarProblem> list = CarProblem.find("from CarProblem as cp where cp.problem.id = ? ", id).fetch(); Set<Car> result = new HashSet<Car>(); for(CarProblem cp : list) result.add(cp.car); return new ArrayList<Car>(result); } } The Model is from Play! framework , so these properties are all public .

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• Do the 'up to date' guarantees provided by final field in Java's memory model extend to indirect ref

  - by mattbh

  The Java language spec defines semantics of final fields in section 17.5: The usage model for final fields is a simple one. Set the final fields for an object in that object's constructor. Do not write a reference to the object being constructed in a place where another thread can see it before the object's constructor is finished. If this is followed, then when the object is seen by another thread, that thread will always see the correctly constructed version of that object's final fields. It will also see versions of any object or array referenced by those final fields that are at least as up-to-date as the final fields are. My question is - does the 'up-to-date' guarantee extend to the contents of nested arrays, and nested objects? An example scenario: Thread A constructs a HashMap of ArrayLists, then assigns the HashMap to final field 'myFinal' in an instance of class 'MyClass' Thread B sees a (non-synchronized) reference to the MyClass instance and reads 'myFinal', and accesses and reads the contents of one of the ArrayLists In this scenario, are the members of the ArrayList as seen by Thread B guaranteed to be at least as up to date as they were when MyClass's constructor completed?

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• How to organize RMI Client-Server eBanking architecture

  - by xenom

  I am developing a secured eBanking service in RMI with a GUI both for Server and Client. The Server must be able to log every operations (new User, deleted User, Withdrawal, Lodgement...) The Client will do these operations. As everything is secured, the Client must at first, create an account with a name and a password in the GUI. After that, the GUI adds the User in the Bank UserList(arrayList) as a new Customer and the User can do several operations. It seems straightforward at first but I think my conception is not correct. Is it correct to send the whole Bank by RMI ? Because at first I thought Bank would be the server but I cannot find another way to do that. Currently, the Client GUI asks for a login and a password, and receives the Bank by RMI. A User is characterized by a name and a hash of the password. private String name; private byte[] passwordDigest; In fact the GUI is doing every security checking and I don't know if it's relevant. When you type login//password, it will search the login in the Bank and compare the hash of the password. In fact I have the impression that the Client knows too much information because when you have the Bank you have everything.. Does it seem correct or do I need to change my implementation ?

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• where is the best palce to count the lazy load property using JPA

  - by Ke

  Let's say we have a "Question" and "Answer" entity, @Entity public class Question extends IdEntity { @Lob private String content; @Transient private int answerTotal; @OneToMany(fetch = FetchType.LAZY) private List<Answer> answers = new ArrayList<Answer>(); ...... I need to tell how many answers for the question every time Question is queryed. So I need to do count: String count = "select count(o) from Answer o WHERE o.question=:q"; My question is, where is the best place to do the count? (Because I did a lot of query about Question entity, by date, by tag, by category, by asker, etc. It is obviously not a good solution to add count operation in each query. My first attempt is to implement a @PostLoad listener, so every time Question entity is loaded, I do count. However, EntityManager cannot be injected in listener. So this way does not work. Any hint?

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• Speed/expensive of SQLite query vs. List.contains() for "in-set" icon on list rows

  - by kpdvx

  An application I'm developing requires that the app main a local list of things, let's say books, in a local "library." Users can access their local library of books and search for books using a remote web service. The app will be aware of other users of the app through this web service, and users can browse other users' lists of books in their library. Each book is identified by a unique bookId (represented as an int). When viewing books returned through a search result or when viewing another user's book library, the individual list row cells need to visually represent if the book is in the user's local library or not. A user can have at most 5,000 books in the library, stored in SQLite on the device (and synchronized with the remote web service). My question is, to determine if the book shown in the list row is in the user's library, would it be better to directly ask SQLite (via SELECT COUNT(*)...) or to maintain, in-memory, a List or int[] array of some sort containing the unique bookIds. So, on each row display do I query SQLite or check if the List or int[] array contains the unique bookId? Because the user can have at most 5,000 books, each bookId occupies 4 bytes so at most this would use ~ 20kB. In thinking about this, and in typing this out, it seems obvious to me that it would be far better for performance if I maintained a list or int[] array of in-library bookIds vs. querying SQLite (the only caveat to maintaining an int[] array is that if books are added or removed I'll need to grow or shrink the array by hand, so with this option I'll most likely use an ArrayList or Vector, though I'm not sure of the additional memory overhead of using Integer objects as opposed to primitives). Opinions, thoughts, suggestions?

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• Twitter friends timeline not returning full history

  - by twofivesevenzero

  I am using twitter4J to get a user's friends timeline, but it is not returning the full available history. I know there are pagination limits (200 per request and 3200 total as per http://bit.ly/ck8ysq) and I am well within those. I make a request like so: private static final int MAX_COUNT = 200; private List<Status> getAllStatuses(long sinceID) throws TwitterException { Twitter twitter = new Twitter(username, password); List<Status> friendsTimelineList = new ArrayList<Status>(); List<Status> tempList; int page = 0; do { page++; tempList = twitter.getFriendsTimeline( new Paging(page, MAX_COUNT, sinceID)); if(tempList == null ) break; friendsTimelineList.addAll(tempList); } while(true); return friendsTimelineList; } This results in only 423 statuses being returned across 3 pages. Any idea why this might be happening?

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• Hibernate saveOrUpdate fails when I execute it on empty table.

  - by Vladimir

  I'm try to insert or update db record with following code: Category category = new Category(); category.setName('catName'); category.setId(1L); categoryDao.saveOrUpdate(category); When there is a category with id=1 already in database everything works. But if there is no record with id=1 I got following exception: org.hibernate.StaleStateException: Batch update returned unexpected row count from update [0]; actual row count: 0; expected: 1: Here is my Category class setters, getters and constructors ommited for clarity: @Entity public class Category { @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; private String name; @ManyToOne private Category parent; @OneToMany(fetch = FetchType.LAZY, mappedBy = "parent") private List<Category> categories = new ArrayList<Category>(); } In the console I see this hibernate query: update Category set name=?, parent_id=? where id=? So looks like hibernates tryis to update record instead of inserting new. What am I doing wrong here?

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• Passing mix of T and T[] to a Java varargs method

  - by rfalke

  Suppose you have a Java method void foobar(int id, String ... args) and want to pass both String arrays and Strings into the method. Like this String arr1[]={"adas", "adasda"}; String arr2[]={"adas", "adasda"}; foobar(0, "adsa", "asdas"); foobar(1, arr1); foobar(2, arr1, arr2); foobar(3, arr1, "asdas", arr2); In Python there is "*" for this. Is there some way better than such rather ugly helper method: static String[] concat(Object... args) { List<String> result = new ArrayList<String>(); for (Object arg : args) { if (arg instanceof String) { String s = (String) arg; result.add(s); } else if (arg.getClass().isArray() && arg.getClass().getComponentType().equals(String.class)) { String arr[] = (String[]) arg; for (String s : arr) { result.add(s); } } else { throw new RuntimeException(); } } return result.toArray(new String[result.size()]); } which allows foobar(4, concat(arr1, "asdas", arr2));

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• How to unselect checkbox in chrome browser

  - by hudi

  in my wicket application I have 3 checkbox in form: add(new CheckBox("1").setOutputMarkupId(true)); add(new CheckBox("2").setOutputMarkupId(true)); add(new CheckBox("3").setOutputMarkupId(true)); form also contain behavior which unselect checboxes add(new AjaxEventBehavior("onclick") { private static final long serialVersionUID = 1L; @Override protected void onEvent(AjaxRequestTarget target) { List<Component> components = new ArrayList<Component>(); if (target.getLastFocusedElementId() != null) { if (target.getLastFocusedElementId().equals("1")) { components.add(get("2")); components.add(get("3")); } else if (target.getLastFocusedElementId().equals("2")) { components.add(get("1")); } else if (target.getLastFocusedElementId().equals("3")) { components.add(get("1")); } for (Component component : components) { component.setDefaultModelObject(null); target.add(component); } } } }); this works good on mozilla browser but in chrome this doesnt work. How I can improve to work this on chrome too ? UPDATE problem is in: target.getLastFocusedElementId() in mozilla this return what I want but in chrome it always return null but I dont know wh UPDATE 2 google chrome has bug in focus element: http://code.google.com/p/chromium/issues/detail?id=1383&can=1&q=window.focus%20type%3aBug&colspec=ID%20Stars%20Pri%20Area%20Type%20Status%20Summary%20Modified%20Owner so I need to do this in other way

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