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  • Using injected EntityManager in class hierarchies

    - by Emre Sahin
    The following code works: @Stateless @LocalBean public class MyClass { @PersistenceContext(name = "MyPU") EntityManager em; public void myBusinessMethod(MyEntity e) { em.persist(e); } } But the following hierarchy gives a TransactionRequiredException in Glassfish 3.0 (and standard JPA annotations with EclipseLink.) at the line of persist. @Stateless @LocalBean public class MyClass extends MyBaseClass { public void myBusinessMethod(MyEntity e) { super.update(e); } } public abstract class MyBaseClass { @PersistenceContext(name = "MyPU") EntityManager em; public void update(Object e) { em.persist(e); } } For my EJB's I collected common code in an abstract class for cleaner code. (update also saves who did the operation and when, all my entities implement an interface.) This problem is not fatal, I can simply copy update and sister methods to subclasses but I would like to keep all of them together in a single place. I didn't try but this may be because my base class is abstract, but I would like to learn a proper method for such a (IMHO common) use case.

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  • Lambda Expressions and Stored Procedures

    - by Jason Summers
    Hi Everyone. I'm trying to mimic the LINQ Where extension method for my ADO.NET DAL methods. Bascially, my aim is to have a single method that I can call. Such as: Product p = Dal.GetProduct(x => x.ProductId == 32); Product p2 = Dal.GetProduct(x => x.ProductName.Contains("Soap")); I then want to dissect those Predicates and send the filter options to parameters in an ADO.NET Stored Procedure call. Any comments greatly appreciated.

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  • How should I handle incomplete packet buffers?

    - by Benjamin Manns
    I am writing a client for a server that typically sends data as strings in 500 or less bytes. However, the data will occasionally exceed that, and a single set of data could contain 200,000 bytes, for all the client knows (on initialization or significant events). However, I would like to not have to have each client running with a 50 MB socket buffer (if it's even possible). Each set of data is delimited by a null \0 character. What kind of structure should I look at for storing partially sent data sets? For example, the server may send ABCDEFGHIJKLMNOPQRSTUV\0WXYZ\0123!\0. I would want to process ABCDEFGHIJKLMNOPQRSTUV, WXYZ, and 123! independently. Also, the server could send ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890LOL123HAHATHISISREALLYLONG without the terminating character. I would want that data set stored somewhere for later appending and processing. Also, I'm using asynchronous socket methods (BeginSend, EndSend, BeginReceive, EndReceive) if that matters.

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  • LINQ to SQL repository - caching data

    - by creativeincode
    I have built my first MVC solution and used the repository pattern for retrieving/inserting/updating my database. I am now in the process of refactoring and I've noticed that a lot of (in fact all) the methods within my repository are hitting the database everytime. This seems overkill and what I'd ideally like is to do is 'cache' the main data object e.g. 'GetAllAdverts' from the database and to then query against this cached object for things like 'FindAdvert(id), AddAdvert(), DeleteAdvert() etc..' I'd also need to consider updating/deleting/adding records to this cache object and the database. What is the best apporoach for something like this? My knowledge of this type of things is minimal and really looking for advice/guidance/tutorial to point me in the right direction. Thanks in advance.

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  • how to implement OOP using QT

    - by kaycee
    hi, this is a simple OOP QT question. my app consists of main window (QMainWindow) and a table (QTableWidget). in the main window i have arguments and variables which i would like to pass to the table class, and to access methods in main widnow class from the table class, how should i do it ? mainwindow.h class MainWindow : public QMainWindow { Q_OBJECT private: int a; int b; Spreadsheet *spreadsheet; public: void set_a(int); void set_b(int); spreadsheet.h class Spreadsheet : public QTableWidget { Q_OBJECT public: Spreadsheet(QWidget *parent = 0); atm i define Spreadsheet like this: spreadsheet = new Spreadsheet(this); and i'd like to access set_a() from spreadsheet.cpp...

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  • How to use a c# datagridview to update a database file just like Access does?

    - by mackeyka
    I have googled everywhere and I am finally giving up and asking here. I am working in Visual Studio 2010 with C#. I have set up a form with a datagridview connected to a MSSQL database and I need to save changes made in the datagridview back to the physical database. I am having some success but I think that I am going about some of it completely wrong because I can not get it to save consistently. What I really want is for the updates to work just like they do when working with Access. When I edit a row in the datagridview and then leave that row, either by selecting another row or by selecting some other control on the form or even by changing to another form or quitting the application the row should be automatically pdated to the physical database. The first part of this question I think is, what is the proper event to use to trigger the save and then second what methods should be used to actually write the data to the database?

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  • ASP.NET MVC: What's the difference in concept between Service and Repository

    - by Richard77
    Hello, The question I'm asking is kind of subjective. I've seen twice, while exercising with real projects such as StoreFront, both Repository and Services. Sometimes they can just be folders or projects attached to the solution. But they contain classes and interfaces. So, I'd like to know what goes to the repository and what goes to the services. So far, I was familiar with repositories (we put methods and properties in the repository to reduce the complexity in the controller). How about the services? So, ASP.NET MVC: What's the difference in concept between Service and Repository? (Maybe none) My question is Kind of subjective, but I'd like to make sure that I'm not missing anything. Thanks for helping

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  • What 'best practices' exist for handing enum heirarchies?

    - by FerretallicA
    I'm curious as to any solutions out there for addressing enum heirarchies. I'm working through some docs on Entity Framework 4 and trying to apply it to a simple inventory tracking program. The possible types for inventory to fall into are as follows: INVENTORY ITEM TYPES: Hardware PC Desktop Server Laptop Accessory Input (keyboards, scanners etc) Output (monitors, printers etc) Storage (USB sticks, tape drives etc) Communication (network cards, routers etc) Software What recommendations are there for handling enums in a situation like this? Are enums even the solution? I don't really want to have a ridiculously normalised database for such a relatively simple experiment (eg tables for InventoryType, InventorySubtype, InventoryTypeToSubtype etc). I don't really want to over-complicate my data model with each subtype being inherited even though no additional properties or methods are included (except PC types which would ideally have associated accessories and software but that's probably out of scope here). It feels like there should be a really simple, elegant solution to this but I can't put my finger on it. Any assistance or input appreciated!

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  • C# IQueryable<T> does my code make sense?

    - by Pandiya Chendur
    I use this to get a list of materials from my database.... public IQueryable<MaterialsObj> FindAllMaterials() { var materials = from m in db.Materials join Mt in db.MeasurementTypes on m.MeasurementTypeId equals Mt.Id select new MaterialsObj() { Id = Convert.ToInt64(m.Mat_id), Mat_Name = m.Mat_Name, Mes_Name = Mt.Name, }; return materials; } But i have seen in an example that has this, public IQueryable<MaterialsObj> FindAllMaterials() { return from m in db.Materials join Mt in db.MeasurementTypes on m.MeasurementTypeId equals Mt.Id select new MaterialsObj() { Id = Convert.ToInt64(m.Mat_id), Mat_Name = m.Mat_Name, Mes_Name = Mt.Name, }; } Is there a real big difference between the two methods... Assigning my linq query to a variable and returning it... Is it a good/bad practise? Any suggestion which should i use?

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  • Model Binding using ASP.NET MVC, getting datainput to the controller.

    - by Calibre2010
    Pretty Basic one here guys. I have a View which holds 2 textfields for input and a submit button <%using (Html.BeginForm("DateRetrival", "Home", FormMethod.Post)){ %> <%=Html.TextBox("sday")%> <%=Html.TextBox("eday")%> <input type="submit" value="ok" id="run"/> <% }%> the following controller action which I want to bind the data input is as follows [AcceptVerbs(HttpVerbs.Get)] public ActionResult DateRetrival() { return View(); } [AcceptVerbs(HttpVerbs.Post)] public ActionResult DateRetrival(string submit) { return null; } When I debug this and look in the action methods parameter, the value is null. When I've entered values in both textboxes and and clicked the submit method.

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  • What is the difference between File and FileInfo in C# ?

    - by Lilitu88
    I've been reading that the static methods of the File Class are better used to perform small and few tasks on a file like checking to see if it exists and that we should use an instance of the FileInfo Class if we are going to perform many operations on a specific file. I understand this and can simply use it that way blindly but I would like to know why is there a difference ? What is it about the way they work that make them suitable for different situations ? What is the point of having this 2 different classes that seem do the same in different ways ? It would be helpful if someone could answer at least one of this questions.

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  • calling webservice in java servlet

    - by Pravin
    I have created a servlet which displays a form having some fields and a submit button and also created a web service having methods which are needed in my servlet. I have deployed the web service on Tomcat 5.5.9/Axis and servlet web application on Tomcat ( same instance of Tomcat) using eclipse. Since one is web service and other is web application both are running on separate instances of tomcat, so when i run them separately i.e servlet without the call to web service and a client that access that webservice it works fine but when i integrate them both i get a error like exception: javax.servlet.ServletException I would like to call the web service and return the result when i press the button Please advice me on how to implement that.

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  • Why do I get Code Analysis CA1062 on an out parameter in this code?

    - by brickner
    I have a very simple code (simplified from the original code - so I know it's not a very clever code) that when I compile in Visual Studio 2010 with Code Analysis gives me warning CA1062: Validate arguments of public methods. public class Foo { protected static void Bar(out int[] x) { x = new int[1]; for (int i = 0; i != 1; ++i) x[i] = 1; } } The warning I get: CA1062 : Microsoft.Design : In externally visible method 'Foo.Bar(out int[])', validate local variable '(*x)', which was reassigned from parameter 'x', before using it. I don't understand why do I get this warning and how can I resolve it without suppressing it? Can new return null? Is this a Visual Studio 2010 bug?

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  • PHP or Javascript or other - Draw simple shapes onto images?

    - by Tommo
    I basically have an image of a world map and i would like to place a pin image at a specified pixel co-ordinate ontop of this world map image. It's for a website, so ideally the solution should be in PHP or Javascript (i'm avoiding Java and Flash as i want it to be as simple as possible). I had a look at the processing.js library but it is way to big and bloated for just performing this simple task. Is there a pre-existing Javascript function which will allow me to do this? Or a more simple javascript library that i can use? (processing.js was a bit too advanced for me, i couldnt get it working lol) In terms of a PHP solution, i would prefer taking the load off the server and onto the client for this task, but i would still like to hear methods for doing it in PHP if they are suitable. Thanks!

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  • .NET Assembly Diff / Compare Tool - What's available?

    - by STW
    I'd like to be able to do a code-level diff between two assemblies; the Diff plug-in for Reflector is the closest thing I've found so far, but to compare the entire assembly is a manual process requiring me to drill-down into every namespace/class/method. The other tools I've found so far appear to be limited to API-level (namespaces, classes, methods) differences--which won't cut it for what I'm looking for. Does anyone know of such a tool? My requirements (from highest to lowest) are: Be able to analyze / reflect the code content of two versions of the same assembly and report the differences Accept a folder or group of assemblies as input; quickly compare them (similar to WinMerge's folder diff's) Quick ability to determine if two assemblies are equivalent at the code level (not just the API's) Allow easy drill-down to view the differences Exporting of reports regarding the differences (Personally I like WinMerge for text diffs, so an application with a similar interface would be great)

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  • Using * in SELECT Query

    - by libregeek
    I am currently porting an application written in MySQL3 and PHP4 to MySQL5 and PHP5. On analysis I found several SQL queries which uses "select * from tablename" even if only one column(field) is processed in PHP. The table has almost 60 columns and it has a primary key. In most cases, the only column used is id which is the primary key. Will there be any performance boost if I use queries in which the column names are explicitly mentioned instead of * ? (In this application there is only one method which we need all the columns and all other methods return only a subset of the columns)

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  • Why use SyncLocks in .NET for simple operations when Interlocked class is available?

    - by rwmnau
    I've been doing simple multi-threading in VB.NET for a while, and have just gotten into my first large multi-threaded project. I've always done everything using the Synclock statement because I didn't think there was a better way. I just learned about the Interlocked Class - it makes it look as though all this: Private SomeInt as Integer Private SomeInt_LockObject as New Object Public Sub IntrementSomeInt Synclock SomeInt_LockObject SomeInt += 1 End Synclock End Sub Can be replaced with a single statement: Interlocked.Increment(SomeInt) This handles all the locking internally and modifies the number. This would be much simpler than writing my own locks for simple operations (longer-running or more complicated operations obviously still need their own locking). Is there a reason why I'd rolling my own locking, using dedicated locking objects, when I can accomplish the same thing using the Interlocked methods?

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  • C# / Visual Studio: production and test code placement

    - by Patrick Linskey
    Hi, In JavaLand, I'm used to creating projects that contain both production and test code. I like this practice because it simplifies testing of internal code without artificially exposing the internals in a project's published API. So far, in my experiences with C# / Visual Studio / ReSharper / NUnit, I've created separate projects (i.e., separate DLLs) for production and test code. Is this the idiom, or am I off base? If this idiomatically correct, what's the right way to deal with exposing classes and methods for test purposes? Thanks, -Patrick

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  • How is method group overload resolution different to method call overload resolution?

    - by thecoop
    The following code doesn't compile (error CS0123: No overload for 'System.Convert.ToString(object)' matches delegate 'System.Converter<T,string>'): class A<T> { void Method(T obj) { Converter<T, string> toString = Convert.ToString; } } however, this does: class A<T> { void Method(T obj) { Converter<T, string> toString = o => Convert.ToString(o); } } intellisense gives o as a T, and the Convert.ToString call as using Convert.ToString(object). In c# 3.5, delegates can be created from co/contra-variant methods, so the ToString(object) method can be used as a Converter<T, string>, as T is always guarenteed to be an object. So, the first example (method group overload resolution) should be finding the only applicable method string Convert.ToString(object o), the same as the method call overload resolution. Why is the method group & method call overload resolution producing different results?

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  • How to inject dependencies into a custom UserNamePasswordValidator in WCF?

    - by Dannerbo
    I'm using a UserNamePasswordValidator in WCF along with Unity for my dependency injection, but since WCF creates the instance of the UserNamePasswordValidator, I cannot inject my container into the class. So how would one go about this? The simplest solution I can think of is to create a static proxy/wrapper class around a static instance of a UnityContainer, which exposes all the same methods... This way, any class can access the container, and I don't need to inject it everywhere. So I could just do UnityContainerWrapper.Resolve() anywhere in code. So basically this solution solves 2 problems for me, I can use it in classes that I'm not creating an instance of, and I can use it anywhere without having to inject the container into a bunch of classes. The only downside I can think of is that I'm now potentially exposing my container to a bunch of classes that wouldn't of had access to the container before. Not really sure if this is even a problem though?

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  • Suggest books/learning path for writing smartphone apps

    - by chibineku
    I have been writing a lot of HTML, CSS, PHP, MySQL and JavaScript lately working on a website, and I would like to move on to 'proper' OOP with an eye to making smartphone apps. I would like to at least cover iPhone and BlackBerry, which means learning Objective C, Cocoa and Java, before learning the specifics of interacting with the devices themselves, such as native bluetooth/GPS/internet API/methods. I would appreciate pointers to books or resources that will get me from a procedural web developer to object oriented app-maker. Most of the reviews of books on Objective C and Java have been mixed. I am about to start working my way through Beginning Java Objects (APress) which I have borrowed from my brother, so even if it's not a good intro at least it was free!

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  • ASP.NET MVC UpdateModel - fields vs properties??

    - by mrjoltcola
    I refactored some common properties into a base class and immediately my model updates started failing. UpdateModel() and TryUpdateModel() did not seem to update inherited public properties. I cannot find detailed info on MSDN nor Google as to the rules or semantics of these methods. The docs are terse (http://msdn.microsoft.com/en-us/library/dd470933.aspx), simply stating: Updates the specified model instance using values from the controller's current value provider. SOLVED: MVC.NET does indeed handle inherited properties just fine. This turned out to have nothing to do with inheritance. My base class was implemented with public fields, not properties. Switching them to formal properties (adding {get; set; }) was all I needed. This has bitten me before, I keep wanting to use simple, public fields. I would argue that fields and properties are syntactically identical, and could be argued to be semantically equivalent, for the user of the class.

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  • JSON in an AJAX request

    - by Josh K
    I have a PHP API I'm working with that outputs everything as JSON. I need to call one of the API methods and parse it out using an AJAX request. I am using jQuery (though it shouldn't matter). When I make the request it errors out with a "parsererror" as the textStatus and a "Syntax Error: invalid label" when I make the request. Simplified code: $.ajax ({ type: "POST", url: "http://mydomain.com/api/get/userlist/"+mid, dataType: "json", dataFilter: function(data, type) { /* Here we assume and pray */ users = eval(data); alert(users[1].id); }, success: function(data, textStatus, XMLHttpRequest) { alert(data.length); // Should be an array, yet is undefined. }, error: function(XMLHttpRequest, textStatus, errorThrown) { alert(textStatus); alert(errorThrown); }, complete: function(XMLHttpRequest, textStatus) { alert("Done"); } });

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  • Android Image Getter for Larger Images

    - by y ramesh rao
    I have used all the Standard Network related code for Getting Images of about 45KB to 75KB but all are failing these methods work fine for Files of about 3-5KB size of Images. How can I achieve Downloading Image of 45 - 75KB for displaying them on an ImageView in Android for my Netowrk Operations the Things I have used are final URL url = new URL(urlString); final URLConnection conn = url.openConnection(); HttpURLConnection httpConn = (HttpURLConnection) conn; httpConn.setAllowUserInteraction(true); httpConn.setInstanceFollowRedirects(true); httpConn.setRequestMethod("GET"); httpConn.connect(); and the Second option that I have had used is:: DefaultHttpClient httpClient = new DefaultHttpClient(); HttpGet getRequest = new HttpGet(urlString); HttpResponse response = httpClient.execute(getRequest); why is this code functional for Smaller Sized Images and not for Larger Size Images. ?

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  • Complex sound handling (I.E. pitch change while looping)

    - by Matthew
    Hi everyone I've been meaning to learn Java for a while now (I usually keep myself in languages like C and Lua) but buying an android phone seems like an excellent time to start. now after going through the lovely set of tutorials and a while spent buried in source code I'm beginning to get the feel for it so what's my next step? well to dive in with a fully featured application with graphics, sound, sensor use, touch response and a full menu. hmm now there's a slight conundrum since i can continue to use cryptic references to my project or risk telling you what the application is but at the same time its going to make me look like a raving sci-fi nerd so bare with me for the brief... A semi-working sonic screwdriver (oh yes!) my grand idea was to make an animated screwdriver where sliding the controls up and down modulate the frequency and that frequency dictates the sensor data it returns. now I have a semi-working sound system but its pretty poor for what its designed to represent and I just wouldn't be happy producing a sub-par end product whether its my first or not. the problem : sound must begin looping when the user presses down on the control the sound must stop when the user releases the control when moving the control up or down the sound effect must change pitch accordingly if the user doesn't remove there finger before backing out of the application it must plate the casing of there device with gold (Easter egg ;P) now I'm aware of how monolithic the first 3 look and that's why I would really appreciate any help I can get. sorry for how bad this code looks but my general plan is to create the functional components then refine the code later, no good painting the walls if the roofs not finished. here's my user input, he set slide stuff is used in the graphics for the control @Override public boolean onTouchEvent(MotionEvent event) { //motion event for the screwdriver view if(event.getAction() == MotionEvent.ACTION_DOWN) { //make sure the users at least trying to touch the slider if (event.getY() > SonicSlideYTop && event.getY() < SonicSlideYBottom) { //power setup, im using 1.5 to help out the rate on soundpool since it likes 0.5 to 1.5 SonicPower = 1.5f - ((event.getY() - SonicSlideYTop) / SonicSlideLength); //just goes into a method which sets a private variable in my sound pool class thing mSonicAudio.setPower(1, SonicPower); //this handles the slides graphics setSlideY ( (int) event.getY() ); @Override public boolean onTouchEvent(MotionEvent event) { //motion event for the screwdriver view if(event.getAction() == MotionEvent.ACTION_DOWN) { //make sure the users at least trying to touch the slider if (event.getY() > SonicSlideYTop && event.getY() < SonicSlideYBottom) { //power setup, im using 1.5 to help out the rate on soundpool since it likes 0.5 to 1.5 SonicPower = 1.5f - ((event.getY() - SonicSlideYTop) / SonicSlideLength); //just goes into a method which sets a private variable in my sound pool class thing mSonicAudio.setPower(1, SonicPower); //this handles the slides graphics setSlideY ( (int) event.getY() ); //this is from my latest attempt at loop pitch change, look for this in my soundPool class mSonicAudio.startLoopedSound(); } } if(event.getAction() == MotionEvent.ACTION_MOVE) { if (event.getY() > SonicSlideYTop && event.getY() < SonicSlideYBottom) { SonicPower = 1.5f - ((event.getY() - SonicSlideYTop) / SonicSlideLength); mSonicAudio.setPower(1, SonicPower); setSlideY ( (int) event.getY() ); } } if(event.getAction() == MotionEvent.ACTION_UP) { mSonicAudio.stopLoopedSound(); SonicPower = 1.5f - ((event.getY() - SonicSlideYTop) / SonicSlideLength); mSonicAudio.setPower(1, SonicPower); } return true; } and here's where those methods end up in my sound pool class its horribly messy but that's because I've been trying a ton of variants to get this to work, you will also notice that I begin to hard code the index, again I was trying to get the methods to work before making them work well. package com.mattster.sonicscrewdriver; import java.util.HashMap; import android.content.Context; import android.media.AudioManager; import android.media.SoundPool; public class SoundManager { private float mPowerLvl = 1f; private SoundPool mSoundPool; private HashMap mSoundPoolMap; private AudioManager mAudioManager; private Context mContext; private int streamVolume; private int LoopState; private long mLastTime; public SoundManager() { } public void initSounds(Context theContext) { mContext = theContext; mSoundPool = new SoundPool(2, AudioManager.STREAM_MUSIC, 0); mSoundPoolMap = new HashMap<Integer, Integer>(); mAudioManager = (AudioManager)mContext.getSystemService(Context.AUDIO_SERVICE); streamVolume = mAudioManager.getStreamVolume(AudioManager.STREAM_MUSIC); } public void addSound(int index,int SoundID) { mSoundPoolMap.put(1, mSoundPool.load(mContext, SoundID, 1)); } public void playUpdate(int index) { if( LoopState == 1) { long now = System.currentTimeMillis(); if (now > mLastTime) { mSoundPool.play(mSoundPoolMap.get(1), streamVolume, streamVolume, 1, 0, mPowerLvl); mLastTime = System.currentTimeMillis() + 250; } } } public void stopLoopedSound() { LoopState = 0; mSoundPool.setVolume(mSoundPoolMap.get(1), 0, 0); mSoundPool.stop(mSoundPoolMap.get(1)); } public void startLoopedSound() { LoopState = 1; } public void setPower(int index, float mPower) { mPowerLvl = mPower; mSoundPool.setRate(mSoundPoolMap.get(1), mPowerLvl); } } ah ha! I almost forgot, that looks pretty ineffective but I omitted my thread which actuality updates it, nothing fancy it just calls : mSonicAudio.playUpdate(1); thanks in advance, Matthew

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