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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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  • 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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  • 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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  • When to use new layouts and when to use new activities?

    - by cmdfrg
    I'm making a game in Android and I'm trying to add a set of menu screens. Each screen takes up the whole display and has various transitions available to other screens. As a rough summary, the menu screens are: Start screen Difficult select screen Game screen. Pause screen. Game over screen. And there are several different ways you can transition between screen: 1 - 2 2 - 3 3 - 4 (pause game) 4 - 1 (exit game) 4 - 3 (resume game) 3 - 5 (game ends) Obviously, I need some stored state when moving between screens, such as the difficulty level select when starting a game and what the player's score is when the game over screen is shown. Can anyone give me some advice for the easiest way to implement the above screens and transitions in Android? All the create/destroy/pause/resume methods make me nervous about writing brittle code if I'm not careful. I'm not fond of using an Activity for each screen. It seems too heavy weight, having to pass data around using intents seems like a real pain and each screen isn't a useful module by itself. As the "back" button doesn't always go back to the previous screen either, my menu layout doesn't seem to fit the activity model well. At the moment, I'm representing each screen as an XML layout file and I have one activity. I set the different buttons on each layout to call setContentView to update the screen the main activity is showing (e.g. the pause button changes the layout to the pause screen). The activity holds onto all the state needed (e.g. the current difficulty level and the game high score), which makes it easy to share data between screens. This seems roughly similar to the LunarLander sample, except I'm using multiple screens. Does what I have at the moment sound OK or am I not doing things the typical Android way? Is there a class I can use (e.g. something like ViewFlipper) that could make my life easier? By the way, my game screen is implemented as a SurfaceView that stores the game state. I need the state in this view to persist between calls to setContentView (e.g. to resume from paused). Is the right idea to create the game view when the activity starts, keep a reference to it and then use this reference with setContentView whenever I want the game screen to appear?

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  • Designing DAOs for data sources other than a database

    - by James P.
    Hi, Until now I've been used to using DAOs to retrieve information from databases. Other sources of data are possible though and I'm wondering if and how the pattern could be applied in general. For example, I'm now working on an application that fetches XML on the web. The XML file could be considered as a data source and the actual fetching is similar in principle to a database request. I'm not quite sure how the DAO could be structured though. Any views on the subject are welcome.

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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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  • Identifying a class which is extending an abstract class

    - by Simon A. Eugster
    Good Evening, I'm doing a major refactoring of http://wiki2xhtml.sourceforge.net/ to finally get better overview and maintainability. (I started the project when I decided to start programming, so – you get it, right? ;)) At the moment I wonder how to solve the problem I'll describe now: Every file will be put through several parsers (like one for links, one for tables, one for images, etc.): public class WikiLinks extends WikiTask { ... } public class WikiTables extends WikiTask { ... } The files will then be parsed about this way: public void parse() { if (!parse) return; WikiTask task = new WikiLinks(); do { task.parse(this); } while ((task = task.nextTask()) != null); } Sometimes I may want to use no parser at all (for files that only need to be copied), or only a chosen one (e.g. for testing purposes). So before running task.parse() I need to check whether this certain parser is actually necessary/desired. (Perhaps via Blacklist or Whitelist.) What would you suggest for comparing? An ID for each WikiTask (how to do?)? Comparing the task Object itself against a new instance of a WikiTask (overhead)?

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  • Major inconsistencies in Zend Framework

    - by John Nall
    Okay first of all let me just say Zend Framework is the greatest tool I have ever used in 30+ years of programming (well, for web development, Qt wins the desktop market). However, through my use I have noticed some glaring and annoying inconsistencies. For instance, Zend_Form_Element's have a setAttrib() method. Now why the hell is this the only method in that API which is abbrev.? Why then am I using setRequired() instead of setReq()? I have more examples, I am extremely nerd raged about this. It is completely ruining what could have been God's gift to web development. FOR FUTURE REFERENCE NEVER ABBREV. THINGS WHEN MAKING AN API. also always filter data before storing it i m o Who do we talk to about this, where something will actually get done about it?

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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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  • 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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  • 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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  • why we can't initialize a servlet using constructor itself?

    - by Reddy
    Why do we have to override init() method in Servlets while we can do the initialization in the constructor and have web container call the constructor passing ServletConfig reference to servlet while calling constructor? Ofcourse container has to use reflection for this but container has to use reflection anyway to call a simple no-arg constructor

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  • Iterative Reduction to Null Matrix

    - by user1459032
    Here's the problem: I'm given a matrix like Input: 1 1 1 1 1 1 1 1 1 At each step, I need to find a "second" matrix of 1's and 0's with no two 1's on the same row or column. Then, I'll subtract the second matrix from the original matrix. I will repeat the process until I get a matrix with all 0's. Furthermore, I need to take the least possible number of steps. I need to print all the "second" matrices in O(n) time. In the above example I can get to the null matrix in 3 steps by subtracting these three matrices in order: Expected output: 1 0 0 0 1 0 0 0 1 0 0 1 1 0 0 0 1 0 0 1 0 0 0 1 1 0 0 I have coded an attempt, in which I am finding the first maximum value and creating the second matrices based on the index of that value. But for the above input I am getting 4 output matrices, which is wrong: My output: 1 0 0 0 1 0 0 0 1 0 1 0 1 0 0 0 0 0 0 0 1 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 My solution works for most of the test cases but fails for the one given above. Can someone give me some pointers on how to proceed, or find an algorithm that guarantees optimality? Test case that works: Input: 0 2 1 0 0 0 3 0 0 Output 0 1 0 0 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 1 0 0

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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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  • example for Singleton pattern

    - by JavaUser
    Hi, Please give me a real time example for singleton pattern . Different threads accessing a shared file is singleton or not ? Since each thread access the same instance of the file not individual instances of their own .

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  • how to use append function in file

    - by sadia
    I want to write in a file but in a way that it should not delete existing data in that file rather it should append that file. Can anybody please help by giving any example related to appending a file? Thank you

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  • How do I get the name of the test method that was run in a testng tear down method?

    - by Zachary Spencer
    Basically I have a tear down method that I want to log to the console which test was just run. How would I go about getting that string? I can get the class name, but I want the actual method that was just executed. Class testSomething() { @AfterMethod public void tearDown() { system.out.println('The test that just ran was....' + getTestThatJustRanMethodName()'); } @Test public void testCase() { assertTrue(1==1); } } should output to the screen: "The test that just ran was.... testCase" However I don't know the magic that getTestThatJustRanMethodName should actually be.

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  • Junit before class ( non static )

    - by Roman
    Are there any best practices to get Junit execute a function once in a test file , and it should also not be static. like @BeforeClass on non static function? Here is an ugly solution : @Before void init(){ if (init.get() == false){ init.set(true); // do once block } } well this is something i dont want to do , and i am looking for an integrated junit solution.

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