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  • changing "enabled" value of a button during runtime in flex

    - by ruchir patwa
    i want to make a button disabled if a datagrid is empty and it should be enabled when there is atleast 1 entry.the entries in the grid are made at runtime.I tried this this is the button: <mx:Button id="update" label="Update Contact" enabled="{isButtonEnabled()}"/> and the function is defined as where dg_contact is the datagrid: public function isButtonEnabled():Boolean { if(dg_contact.selectedIndex==-1) { return false; } else { return true; } } where am i going wrong?

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  • Does acos, atan functions in stl uses lots of cpu cycles

    - by jan
    Hi all, I wanted to calculate the angle between two vectors but I have seen these inverse trig operations such as acos and atan uses lots of cpu cycles. Is there a way where I can get this calculation done without using these functions? Also, does these really hit you when you in your optimization?

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  • Collision Detection for arbitrarily sized, positioned and rotated rectangles in XNA

    - by Stefan
    I'm working with xna in C# and in my game I will have a variety of space ships flying all over the place. They will each have an arbitrary rotation, size and position in space and I need a method to determine when they collide. Ideally the method would take two Rectangles, two doubles and two Vector2s for size, rotation and position respectively and return a boolean that indicates whether they have intersected or not.

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  • how to selectively filter items in a collection

    - by Samuel
    I use the following snippet to filter the list of selected users, where isSelected is a boolean variable. Is there a simpler way (helper function) to populate the selectedUsers collection instead of writing the following lines of code. List<User> selectedUsers = new ArrayList<User>(0); for (User user : this.getUsers()) { if (user.isSelected()) { selectedUsers.add(user.getId()); } }

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  • Erlang: What are the pros and cons of different methods for avoiding intermediate variables?

    - by erlacher
    At one point while traveling the web, I came across a great page which contrasted the clarity and terseness of different methods of doing a sequence of operations without having to make a bunch of throwaway variables, e.g., Var1, Var2, Var3. It tried list comprehensions, folds, maps, etc. For some reason, now matter what I google, I can't find it again. Anyone have any idea what I'm talking about? Or want to explore the topic anyway?

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  • How does one use TrafficStats.incrementOperationCount()?

    - by Dheeraj
    The documentation for TrafficStats.incrementOperationCount() says: Increment count of network operations performed under the given accounting tag. This can be used to derive bytes-per-operation. I want to find the total number of bytes transferred during a particular network operation. Since this API claims to help in deriving bytes-per-operation, can someone help me understand how to use it?

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  • Java library for trees similar to JGraphT for graphs?

    - by lexicore
    I'm a big fan of JGraphT, a Java library for graphs. Could anyone recommend a similar Java library for trees? Preferrably FOSS. What I need is a good API, preferrably typesafe with generics which allows modelling different kinds of trees (with some user data attached to verticies/edges) and run different algorithms and operations on these trees. For instance, traverse or balance. At the moment I'm not interested in visualization of trees.

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  • Why can't c# calculate exact values of mathematical functions

    - by Timo Willemsen
    Hey everyone, Why can't c# do any exact operations. Math.Pow(Math.Sqrt(2.0),2) == 2.0000000000000004 I know how doubles work, I know where the rounding error is from, I know that it's almost the correct value, and I know that you can't store infinite numbers in a finite double. But why isn't there a way that c# can calculate it exactly, while my calculator can do it. Edit It's not about my calculator, I was just giving an example: http://www.wolframalpha.com/input/?i=Sqrt%282.000000000000000000000000000000000000000000000000000000000000000000000000000000001%29%5E2 Cheers

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  • A single button should be used in all the forms.

    - by mugamath
    i need to use a single button for all forms in a vb.net project. The single button should be called in the forms to perform operations. For eg., In a form i need to save, update the records. When i call the button, save and update buttons should be appeared at runtime using the single button. guide me....

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  • [C++] STL list - how to find a list element by its object fields

    - by Dominic Bou-Samra
    I have a list: list<Unit *> UnitCollection; containing Unit objects, which has an accessor like: bool Unit::isUnit(string uCode) { if(this->unitCode == uCode) return true; else return false; } How do I search my UnitCollection list by uCode and return the corresponding element (preferably it's index). I have looked at the find() method, but i'm not sure you can pass a boolean method in instead of a searched item parameter if that makes sense.

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  • Ruby complex validation

    - by pcasa
    Have a product that belongs to a category. Want to create a promotion for a short period of time (lets say a week or two), but their can be only one promotion per category during that time. How can I create a custom validation for this? product class belongs_to :categories name:string desc:text reg_price:decimal category_id:integer promo_active:boolean promo_price:decimal promo_start:datetime promo_end:datetime end category class has_many :products name:string end

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  • creating a shared library from c++ source file

    - by navinbecse
    when I tried to create a shared library file using the "cl" command in the vc++ command prompt, it shows a error saying "Can't open include file "jni.h": No such file or directory"... the jni.h is tried to be included in the machine generated header file from java class... i am using this for java navite interface operations... can any one help me...

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  • A Surface view and a canvas to move Bitmap

    - by John Apple Sim
    I have a SurfaceView and I want the Bitmap Logo inside it in the canvas to be movable What I'm doing wrong ? static float x, y; Bitmap logo; SurfaceView ss = (SurfaceView) findViewById(R.id.svSS); logo = BitmapFactory.decodeResource(getResources(), R.drawable.logo); x = 40; y = 415; ss.setOnTouchListener(new View.OnTouchListener() { @Override public boolean onTouch(View v, MotionEvent me) { try { Thread.sleep(50); } catch (InterruptedException e) { e.printStackTrace(); } switch(me.getAction()) { case MotionEvent.ACTION_DOWN: x = me.getX(); y = me.getY(); break; case MotionEvent.ACTION_UP: x = me.getX(); y = me.getY(); break; case MotionEvent.ACTION_MOVE: x = me.getX(); y = me.getY(); break; } return true; } }); public class OurView extends SurfaceView implements Runnable{ Thread t = null; SurfaceHolder holder; boolean isItOK = false; public OurView(Context context) { super(context); holder = getHolder(); } public void run (){ while (isItOK == true){ //canvas DRAWING if (!holder.getSurface().isValid()){ continue; } Canvas c = holder.lockCanvas(); c.drawARGB(255, 200, 100, 100); c.drawBitmap(logo, x,y,null); holder.unlockCanvasAndPost(c); } } public void pause(){ isItOK = false; while(true){ try { t.join(); } catch (InterruptedException e) { e.printStackTrace(); } break; } t = null; } public void resume(){ isItOK = true; t = new Thread(this); t.start(); } } Now the surface view is just black .. nothing happens also its not colored 200, 100, 100

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  • How to enforce a 5-minute per post rule in a session object in Java?

    - by John
    I'm trying to figure out how to enforce a 5 minute per post/action rule. I'm developing a web application with Wicket in Java and I've got a session class which I was planning on using to keep track of these timers on a per-user basis. I wasn't planning on storing the timestamp in a database. public boolean isAllowedToPost() { if(null OR has 5 minutes passed since last post) { // set the new timestamp return true; } else { return false; } }

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  • DFS Backtracking with java

    - by Cláudio Ribeiro
    I'm having problems with DFS backtracking in an adjacency matrix. Here's my code: (i added the test to the main in case someone wants to test it) public class Graph { private int numVertex; private int numEdges; private boolean[][] adj; public Graph(int numVertex, int numEdges) { this.numVertex = numVertex; this.numEdges = numEdges; this.adj = new boolean[numVertex][numVertex]; } public void addEdge(int start, int end){ adj[start-1][end-1] = true; adj[end-1][start-1] = true; } List<Integer> visited = new ArrayList<Integer>(); public Integer DFS(Graph G, int startVertex){ int i=0; if(pilha.isEmpty()) pilha.push(startVertex); for(i=1; i<G.numVertex; i++){ pilha.push(i); if(G.adj[i-1][startVertex-1] != false){ G.adj[i-1][startVertex-1] = false; G.adj[startVertex-1][i-1] = false; DFS(G,i); break; }else{ visited.add(pilha.pop()); } System.out.println("Stack: " + pilha); } return -1; } Stack<Integer> pilha = new Stack(); public static void main(String[] args) { Graph g = new Graph(6, 9); g.addEdge(1, 2); g.addEdge(1, 5); g.addEdge(2, 4); g.addEdge(2, 5); g.addEdge(2, 6); g.addEdge(3, 4); g.addEdge(3, 5); g.addEdge(4, 5); g.addEdge(6, 4); g.DFS(g, 1); } } I'm trying to solve the euler path problem. the program solves basic graphs but when it needs to backtrack, it just does not do it. I think the problem might be in the stack manipulations or in the recursive dfs call. I've tried a lot of things, but still can't seem to figure out why it does not backtrack. Can somebody help me ?

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  • how to swap array-elements to transfer the array from a column-like into a row-like representation

    - by Christian Ammer
    For example: the array a1, a2, a3, b1, b2, b3, c1, c2, c3, d1, d2, d3 represents following table a1, b1, c1, d1 a2, b2, c2, d2 a3, b3, c3, d3 now i like to bring the array into following form a1, b1, c1, d1, a2, b2, c2, d2, a3, b3, c3, d3 Does an algorithm exist, which takes the array (from the first form) and the dimensions of the table as input arguments and which transfers the array into the second form? I thougt of an algorithm which doesn't need to allocate additional memory, instead i think it should be possible to do the job with element-swap operations.

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  • Drawbacks of using an integer as a bitfield?

    - by Mark
    I have a bunch of boolean options for things like "accepted payment types" which can include things like cash, credit card, cheque, paypal, etc. Rather than having a half dozen booleans in my DB, I can just use an integer and assign each payment method an integer, like so PAYMENT_METHODS = ( (1<<0, 'Cash'), (1<<1, 'Credit Card'), (1<<2, 'Cheque'), (1<<3, 'Other'), ) and then query the specific bit in python to retrieve the flag. I know this means the database can't index by specific flags, but are there any other drawbacks?

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  • Help me to find a better approach-Design Pattern

    - by DJay
    I am working on an ASP.Net web application in which several WCF services are being used. At client level, I am creating channel factory mechanism to invoke service operations. Right now, I have created an assembly having classes used for channel factory creation code for every service. As per my assumption this is some sort of facade pattern. Please help me to find a better approach or any design pattern, which I can use here.

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  • How to define schema for an ActiveRecord model?

    - by Eric Stanton
    I can find how to define columns only when doing migrations. However i do not need to migrate my model. I want to work with it "virtually". Does AR read columns data only from db? Any way to define columns like in DataMapper? class Post include DataMapper::Resource property :id, Serial property :title, String property :published, Boolean end Now i can play with my model without migrations/connections.

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  • Main Memory Database with C++ Interface

    - by myahya
    I am looking for a main memory database with a C++ interface. I am looking for a database with a programmatic query interface and preferably one that works with native C++ types. SQLLite, for example, takes queries as string and needs to perform parsing ... which is time consuming. The operations I am looking for are: Creation of tables of arbitrary dimensions (number of attributes) capable of storing integer types. Support for insertion, deletion, selection, projection and (not a priority) joins.

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  • Permanent file changes on iPhone simulator

    - by Cesar
    I'm in trouble with paths, relative paths, NSBundle and all the path/file related operations :) While i run the simulator everthing goes right but all the file changes are not permanent, so everytime i run my app i have to repeat the initial setup of my app. The question: What is the proper way to read and write files (from resource dir) and make all the file changes permanent (updated into the project folder) ? Thanks

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