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  • Is there some way to assume @Nullable as default? (using FindBugs or any other free tool).

    - by alex2k8
    Consider such code public void m1(String text) { if(text == null) text = "<empty>"; System.out.println(text.toLowerCase()); } And this is a buggy version: public void m1(String text) { System.out.println(text.toLowerCase()); } If null value passed, the NullPointerException may be thrown. I would like the static-analysis tool (e.g. FindBugs) to report this issue. Unsuccessfully the FindBugs (at least by default) requires me to specify @Nullable annotation explicitly. public void m1(@Nullable String text) { System.out.println(text.toLowerCase()); // FindBugs: text must be nonnull but is marked as nullable } The problem is that if I forget to annotate it, the bug will be missed!!! How can I make the FindBugs (or any other free tool) to assume @Nullable by default?

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  • What else I must do allow my method to handle any type of objects

    - by NewHelpNeeder
    So to allow any type object I must use generics in my code. I have rewrote this method to do so, but then when I create an object, for example Milk, it won't let me pass it to my method. Ether there's something wrong with my generic revision, or Milk object I created is not good. How should I pass my object correctly and add it to linked list? This is a method that causes error when I insert an item: public void insertFirst(T dd) // insert at front of list { Link newLink = new Link(dd); // make new link if( isEmpty() ) // if empty list, last = newLink; // newLink <-- last else first.previous = newLink; // newLink <-- old first newLink.next = first; // newLink --> old first first = newLink; // first --> newLink } This is my class I try to insert into linked list: class Milk { String brand; double size; double price; Milk(String a, double b, double c) { brand = a; size = b; price = c; } } This is test method to insert the data: public static void main(String[] args) { // make a new list DoublyLinkedList theList = new DoublyLinkedList(); // this causes: // The method insertFirst(Comparable) in the type DoublyLinkedList is not applicable for the arguments (Milk) theList.insertFirst(new Milk("brand", 1, 2)); // insert at front theList.displayForward(); // display list forward theList.displayBackward(); // display list backward } // end main() } // end class DoublyLinkedApp Declarations: class Link<T extends Comparable<T>> {} class DoublyLinkedList<T extends Comparable<T>> {}

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  • Calculating the angle between two points

    - by kingrichard2005
    I'm currently developing a simple 2D game for Android. I have a stationary object that's situated in the center of the screen and I'm trying to get that object to rotate and point to the area on the screen that the user touches. I have the constant coordinates that represent the center of the screen and I can get the coordinates of the point that the user taps on. I'm using the formula outlined in this forum: How to get angle between two points? -It says as follows "If you want the the angle between the line defined by these two points and the horizontal axis: double angle = atan2(y2 - y1, x2 - x1) * 180 / PI;". -I implemented this, but I think the fact the I'm working in screen coordinates is causing a miscalculation, since the Y-coordinate is reversed. I'm not sure if this is the right way to go about it, any other thoughts or suggestions are appreciated.

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  • SensorManager method crashes program

    - by Aidan
    Hi guys, When I run the following method my Android application crashes. I can't find the error because I get a "Source Not Found" error. Anyone have any idea's what I'm doing wrong? public void bearing(){ SensorManager sm = (SensorManager)getSystemService(Context.SENSOR_SERVICE); Sensor aSensor = sm.getDefaultSensor(Sensor.TYPE_ACCELEROMETER); Sensor mfSensor = sm.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD); sm.registerListener(myAccelerometerListener, aSensor, SensorManager.SENSOR_DELAY_UI); sm.registerListener(myMagneticFieldListener, mfSensor, SensorManager.SENSOR_DELAY_UI); float[] values = new float[3]; float[] R = new float[9]; SensorManager.getRotationMatrix(R, null, accelerometerValues, magneticFieldValues); SensorManager.getOrientation(R, values); //Convert from Radians to degrees values[0] = (float) Math.toDegrees(values[0]); values[1] = (float) Math.toDegrees(values[1]); values[2] = (float) Math.toDegrees(values[2]); }

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  • No exit option if something is running

    - by max
    How can I catch something going on if the user chooses the exit option from a menu? I mean I'd like to be able to manage the event of a user who is going to close the application but some activity is being performed so he/she shouldn't be able to exit. Here's the code I wrote. In a nutshell : recording is being performed -- user clicks exit -- WARNING "Process is running you can't do it"(The process goes on) nothing is running -- user clicks exit -- application closes Is it possible to solve the problem by just adding a few lines of code without having to rewrite the entire program? thanks very much in advance. MAX exitAction = new AbstractAction("Exit") { public void actionPerformed(ActionEvent e) { System.exit(0); } }; exitAction.putValue(Action.NAME, "Exit"); // description exitAction.putValue(Action.SHORT_DESCRIPTION, "Exit application");

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  • Could someone help me debug my app (not very big)?

    - by Alex
    Not sure if this kind of help is accepted to ask for here, tell me if it isn't. It has to get done before tomorrow, it's not entirerly finished but it should work somewhat ok by now. I'm trying to use the Eclipse debugger (not very used to it). I have my top-level or main class, which is Game, in which I have a constructor and a main method. In the main method I create a new "Game", initiating the constructor. public static void main(String[] args){ Game chess = new Game(); } public Game(){ Board board = new Board(); That's the first thing the debugger reacts to: Thread [main] (Suspended) ClassNotFoundException(Object).<init>() line: 20 [local variables unavailable] ClassNotFoundException(Throwable).<init>(String, Throwable) line: 217 ClassNotFoundException(Exception).<init>(String, Throwable) line: not available ClassNotFoundException.<init>(String) line: not available URLClassLoader$1.run() line: not available AccessController.doPrivileged(PrivilegedExceptionAction<T>, AccessControlContext) line: not available [native method] Launcher$ExtClassLoader(URLClassLoader).findClass(String) line: not available Launcher$ExtClassLoader.findClass(String) line: not available Launcher$ExtClassLoader(ClassLoader).loadClass(String, boolean) line: not available Launcher$AppClassLoader(ClassLoader).loadClass(String, boolean) line: not available Launcher$AppClassLoader.loadClass(String, boolean) line: not available Launcher$AppClassLoader(ClassLoader).loadClass(String) line: not available Game.<init>() line: 15 Game.main(String[]) line: 11 Line 11 is the one line in my main method, line 15 is the instantiation of "board".

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  • My method is too specific. How can I make it more generic?

    - by EricBoersma
    I have a class, the outline of which is basically listed below. import org.apache.commons.math.stat.Frequency; public class WebUsageLog { private Collection<LogLine> logLines; private Collection<Date> dates; WebUsageLog() { this.logLines = new ArrayList<LogLine>(); this.dates = new ArrayList<Date>(); } SortedMap<Double, String> getFrequencyOfVisitedSites() { SortedMap<Double, String> frequencyMap = new TreeMap<Double, String>(Collections.reverseOrder()); //we reverse order to sort from the highest percentage to the lowest. Collection<String> domains = new HashSet<String>(); Frequency freq = new Frequency(); for (LogLine line : this.logLines) { freq.addValue(line.getVisitedDomain()); domains.add(line.getVisitedDomain()); } for (String domain : domains) { frequencyMap.put(freq.getPct(domain), domain); } return frequencyMap; } } The intention of this application is to allow our Human Resources folks to be able to view Web Usage Logs we send to them. However, I'm sure that over time, I'd like to be able to offer the option to view not only the frequency of visited sites, but also other members of LogLine (things like the frequency of assigned categories, accessed types [text/html, img/jpeg, etc...] filter verdicts, and so on). Ideally, I'd like to avoid writing individual methods for compilation of data for each of those types, and they could each end up looking nearly identical to the getFrequencyOfVisitedSites() method. So, my question is twofold: first, can you see anywhere where this method should be improved, from a mechanical standpoint? And secondly, how would you make this method more generic, so that it might be able to handle an arbitrary set of data?

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  • How to use timer in a thread

    - by Anjaneyulu
    Hi, I would like to send email notifications to users of my project exactly at 8 a.m, Here we are using a thread to send emails to the user. I would like to send some emails exactly at 8 A.M. How can I execute that perticular logic in this Thread. Please help me.

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  • Performance side effect with static internal Util classes?

    - by Fostah
    For a util class that contains a bunch of static functionality that's related to the same component, but has different purposes, I like to use static internal classes to organize the functionality, like so: class ComponentUtil { static class Layout { static int calculateX(/* ... */) { // ... } static int calculateY(/* ... */) { // ... } } static class Process { static int doThis(/* ... */) { // ... } static int doThat(/* ... */) { // ... } } } Is there any performance degradation using these internal classes vs. just having all the functionality in the Util class?

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  • Hibernate Query - Get latest versions by timestamp?

    - by Slim
    I have a database that is being used as a sort of version control system. That is, instead of ever updating any rows, I add a new row with the same information. Each row also contains a version column that is a date timestamp, so the only difference is the new row will have a more recent timestamp. What I'm having trouble with is writing an efficient hibernate query to return the latest version of these rows. For the sake of example, these are rows in a table called Product, the timestamped column is version. There are multiple versions of multiple products in the table. So there may be multiple versions (rows) of ProductA, multiple versions of ProductB, etc. And I would like to grab the latest version of each. Can I do this in just a single hibernate query? session.createQuery("select product from Product product where...?"); Or would this require some intermediate steps?

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  • Hash Table question [closed]

    - by Fatimah
    I need your help to solve this program ... Implement a separate chaining hash table that stores strings. You’ll need a hash function that converts string into an index number. Assume the strings will be lowercase words, so 26 characters will suffice.

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  • Activiti Engine: Task Event - User is null

    - by sockeqwe
    I have a problem, which should be simple to solve, but i can't find the method to call to solve this problem: My problem is, that every Task Event (org.activiti.engine.task.Event) returnes null by calling Event.getUserId(); If I take a look into the database I see that the database table ACT_HI_COMMENT has null as value for the column USER_ID_ for every row. I generate these TaskEvents programmatically by calling (for example) processEngine.getTaskService().addComment(task.getId(), null, commentMessage); processEngine.getTaskService().addUserIdentityLink(task.getId(), user.getId(), IDENTITY_LINK_OBSERVER); I guess there is a simple method that I must call to solve this problem, something like processEngine.setCurrentUser(authenticatedUser.getId()); Any suggestions?

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  • client side spring

    - by Gholi
    I wanna sth like Spring framework to use in client side. Actually I am going to abstract ui from data sources that may be added to system while it is up. An XML will be injected to system and ui will be generated automatically. Client side use would be able to search on new data source while objects are created in client side. Thanks

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  • which design choose? - pros and cons

    - by Guarava Makanili
    Which of these 3 approches would choose and why? // This is the one I would choose class Car { } class FeeCalculator { public double calculateFee(Car car) { return 0; } } // in that case the problem might be when we use ORM framework and we try to invoke save with parameter Car class Car { private FeeCalculator calculator; public double calculateFee() { return calculator.calculateFee(this); } } class FeeCalculator { public double calculateFee(Car car) { return 0; } } // in that case the problem mentioned above is solved, but I don't like this design class Car { public double calculateFee(FeeCalculator calculator) { return calculator.calculateFee(this); } } class FeeCalculator { public double calculateFee(Car car) { return 0; } }

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  • android listview loadmore button with xml parsing

    - by user1780331
    Hi i have to developed listview with load more button using xml parsing in android application. Here i have faced some problem. my xml feed is empty means how can hide the load more button on last page. i have used below code here. public class CustomizedListView extends Activity { // All static variables private String URL = "http://dev.mmm.com/xctesting/xcart444pro/retrieve.php?page=1"; // XML node keys static final String KEY_SONG = "Order"; static final String KEY_TITLE = "orderid"; static final String KEY_DATE = "date"; static final String KEY_ARTIST = "payment_method"; int current_page = 1; ListView lv; LazyAdapter adapter; ProgressDialog pDialog; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); lv = (ListView) findViewById(R.id.list); ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>(); XMLParser parser = new XMLParser(); String xml = parser.getXmlFromUrl(URL); // getting XML from URL Document doc = parser.getDomElement(xml); // getting DOM element NodeList nl = doc.getElementsByTagName(KEY_SONG); // looping through all song nodes <song> for (int i = 0; i < nl.getLength(); i++) { // creating new HashMap HashMap<String, String> map = new HashMap<String, String>(); Element e = (Element) nl.item(i); // adding each child node to HashMap key => value map.put(KEY_ID, parser.getValue(e, KEY_ID)); map.put(KEY_TITLE, parser.getValue(e, KEY_TITLE)); map.put(KEY_ARTIST, parser.getValue(e, KEY_ARTIST)); songsList.add(map); } Button btnLoadMore = new Button(this); btnLoadMore.setText("Load More"); btnLoadMore.setBackgroundResource(R.drawable.lgnbttn); // Adding Load More button to lisview at bottom lv.addFooterView(btnLoadMore); // Getting adapter adapter = new LazyAdapter(this, songsList); lv.setAdapter(adapter); btnLoadMore.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View arg0) { // Starting a new async task new loadMoreListView().execute(); } }); } private class loadMoreListView extends AsyncTask<Void, Void, Void> { @Override protected void onPreExecute() { // Showing progress dialog before sending http request pDialog = new ProgressDialog( CustomizedListView.this); pDialog.setMessage("Please wait.."); //pDialog.setIndeterminateDrawable(getResources().getDrawable(R.drawable.my_progress_indeterminate)); pDialog.setIndeterminate(true); pDialog.setCancelable(false); pDialog.show(); pDialog.setContentView(R.layout.custom_dialog); } protected Void doInBackground(Void... unused) { current_page += 1; // Next page request URL = "http://dev.mmm.com/xctesting/xcart444pro/retrieve.php?page=" + current_page; ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>(); XMLParser parser = new XMLParser(); String xml = parser.getXmlFromUrl(URL); // getting XML from URL Document doc = parser.getDomElement(xml); // getting DOM element NodeList nl = doc.getElementsByTagName(KEY_SONG); NodeList nl = doc.getElementsByTagName(KEY_SONG); if (nl.getLength() == 0) { btnLoadMore.setVisibility(View.GONE); pDialog.dismiss(); } else // looping through all item nodes <item> for (int i = 0; i < nl.getLength(); i++) { // creating new HashMap HashMap<String, String> map = new HashMap<String, String>(); Element e = (Element) nl.item(i); // adding each child node to HashMap key => value map.put(KEY_ID, parser.getValue(e, KEY_ID)); map.put(KEY_TITLE, parser.getValue(e, KEY_TITLE)); map.put(KEY_ARTIST, parser.getValue(e, KEY_ARTIST)); songsList.add(map); } // get listview current position - used to maintain scroll position int currentPosition = lv.getFirstVisiblePosition(); // Appending new data to menuItems ArrayList adapter = new LazyAdapter( CustomizedListView.this, songsList); lv.setAdapter(adapter); lv.setSelectionFromTop(currentPosition + 1, 0); } }); return (null); } protected void onPostExecute(Void unused) { // closing progress dialog pDialog.dismiss(); } } } EDIT: Here i have to run the app means the listview is displayed on perpage 4 items.my last page having 1 item.please refer this screenshot:http://screencast.com/t/fTl4FETd In last page i have to click the load more button means have to go next activity and successfully hide the button on empty page..please refer this screenshot:http://screencast.com/t/wyG5zdp3r i have to check the condition for empty page: if (nl.getLength() == 0) { btnLoadMore.setVisibility(View.GONE); pDialog.dismiss(); } How can i write the conditon fot last page?????pleas ehelp me Here i wish to need the o/p is hide the button on last page. Please help me.how can i check the condition.give me some code programmatically.

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  • How do I add an object to a binary tree based on the value of a member variable?

    - by Max
    How can I get a specific value from an object? I'm trying to get a value of an instance for eg. ListOfPpl newListOfPpl = new ListOfPpl(id, name, age); Object item = newListOfPpl; How can I get a value of name from an Object item?? Even if it is easy or does not interest you can anyone help me?? Edited: I was trying to build a binary tree contains the node of ListOfPpl, and need to sort it in the lexicographic. Here's my code for insertion on the node. Any clue?? public void insert(Object item){ Node current = root; Node follow = null; if(!isEmpty()){ root = new Node(item, null, null); return; }boolean left = false, right = false; while(current != null){ follow = current; left = false; right = false; //I need to compare and sort it if(item.compareTo(current.getFighter()) < 0){ current = current.getLeft(); left = true; }else { current = current.getRight(); right = true; } }if(left) follow.setLeft(new Node(item, null, null)); else follow.setRight(new Node(item, null, null)); }

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  • Global variable in a recursive function how to keep it at zero?

    - by Grammin
    So if I have a recursive function with a global variable var_: int var_; void foo() { if(var_ == 3) return; else var_++; foo(); } and then I have a function that calls foo() so: void bar() { foo(); return; } what is the best way to set var_ =0 everytime foo is called thats not from within itself. I know I could just do: void bar() { var_ =0; foo(); return; } but I'm using the recursive function a lot and I don't want to call foo and forget to set var_=0 at a later date. Does anyone have any suggestions on how to solve this? Thanks, Josh

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  • isAlive problem..Help to understand how it works

    - by max
    I get this error: "non-static method isAlive() cannot be referenced from a static context" what's wrong with this code..please. I'd like to detect if the thread is alive... Any help in terms of code will be highly appreciated..thanks max class RecThread extends Thread { public void run() { recFile = new File("recorded_track.wav"); // Output file type AudioFileFormat.Type fileType = null; fileType = AudioFileFormat.Type.WAVE; // if rcOn =1 thread is alive int rcOn; try { // starts recording targetDataLine.open(audioFormat); targetDataLine.start(); AudioSystem.write(new AudioInputStream(targetDataLine), fileType, recFile); if (RecThread.isAlive() == true) { rcOn =1; } else { rcOn =0; } } catch (Exception e) { showException(e); } // update actions recAction.setEnabled(true); stopRecAction.setEnabled(false); } }

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