This is a nice tutorial:

http://android-developers.blogspot.de/2009/05/painless-threading.html

Or this for the UI thread:

http://developer.android.com/guide/faq/commontasks.html#threading

Or here a very practical one:

http://www.androidacademy.com/1-tutorials/43-hands-on/115-threading-with-android-part1

and another one about procceses and threads

http://developer.android.com/guide/components/processes-and-threads.html

One of Androids powerful feature is the [AsyncTask][1] class.

To work with it, you have to first extend it and override `doInBackground`(...). 
`doInBackground` automatically executes on a worker thread, and you can add some
listeners on the UI Thread to get notified about status update, those functions are
called: `onPreExecute()`, `onPostExecute()` and `onProgressUpdate()`

You can find a example [here][2].

Refer to below post for other alternatives:

https://stackoverflow.com/questions/6964011/handler-vs-asynctask-vs-thread



  [1]: https://developer.android.com/reference/android/os/AsyncTask.html
  [2]: http://android-jotting.blogspot.com/2010/09/using-asynctasks-in-android.html

Here is a simple threading example for Android. It&#39;s very basic but it should help you to get a perspective. 

Android code - Main.java

    package test12.tt;
    
    import android.app.Activity;
    import android.os.Bundle;
    import android.widget.TextView;
    
    public class Test12Activity extends Activity {
    
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.main);
        	final TextView txt1 = (TextView) findViewById(R.id.sm);
    
            new Thread(new Runnable() { 
            	public void run(){        
    		    txt1.setText(&quot;Thread!!&quot;);
               	}
    	    }).start();
            
        }    
    }

Android application xml - main.xml

    &lt;?xml version=&quot;1.0&quot; encoding=&quot;utf-8&quot;?&gt;
    &lt;LinearLayout xmlns:android=&quot;http://schemas.android.com/apk/res/android&quot;
        android:orientation=&quot;vertical&quot;
        android:layout_width=&quot;fill_parent&quot;
        android:layout_height=&quot;fill_parent&quot;&gt;

        &lt;TextView  
        android:id = &quot;@+id/sm&quot;
        android:layout_width=&quot;fill_parent&quot; 
        android:layout_height=&quot;wrap_content&quot; 
        android:text=&quot;@string/hello&quot;/&gt;

    &lt;/LinearLayout&gt;

&gt; **Possible Duplicate:**  
&gt; [MetadataException: Unable to load the specified metadata resource](https://stackoverflow.com/questions/689355/metadataexception-unable-to-load-the-specified-metadata-resource)  

&lt;!-- End of automatically inserted text --&gt;

I hope someone can help with this. i have tried following other posts on here and dozens on other sites but i can get this working.

the entity framework was all working, then the next day just started giving me the error: Unable to load the specified metadata resource. on the constructor of the entities class.

I have checked the connection strings, deleted and re added everything but i still cant get this working.

my model namespace is WraithNath.co.uk.Models

the metadata artificat is embed in assembly

my connection strings are as follows:

    &lt;add name=&quot;ConnectionString&quot; connectionString=&quot;Data Source=.\SQL2008;AttachDbFilename=|DataDirectory|\WraithNath.co.uk.mdf;Integrated Security=True;&quot; providerName=&quot;System.Data.SqlClient&quot; /&gt;
       &lt;add name=&quot;Entities&quot; connectionString=&quot;metadata=res://*/Models.WraithNath.co.uk.csdl|res://*/Models.WraithNath.co.uk.ssdl|res://*/Models.WraithNath.co.uk.msl;provider=System.Data.SqlClient;provider connection string=&amp;quot;Data Source=.\SQL2008;AttachDbFilename=|DataDirectory|\WraithNath.co.uk.mdf;Integrated Security=True;MultipleActiveResultSets=True&amp;quot;&quot; providerName=&quot;System.Data.EntityClient&quot; /&gt;

 
I cant find the 3 files i need in the assembly when looking at it in Reflector.

Is there a step by step guide to sort this out? i have already tried every link on the first 3 pages of google for search results &#39;entity framework Unable to load the specified metadata resource&#39;.

entity framework Unable to load the specified metadata resource

I have `PictureBox picture`.

I use:

    picture.Size = bmp.Size;
    picture.Image = bmp;

Let&#39;s say there are two integers `maxWidth` and `maxHeigth`.  
I want to add vertical/horizontal scrollbar to `picture` when its size exceeds `maxWidth` and/or `maxHeight`. How can I do that?

How can I get scrollbars on Picturebox

I want some simple example on thread creation and invoking of threads in android. 

Threading Example in Android

<p>I want some simple example on thread creation and invoking of threads in android.</p>


I have got FFmpeg compiled (libffmpeg.so) on Android. Now I have to build either an application like RockPlayer or use existing Android multimedia framework to invoke FFmpeg.

1. Do you have steps / procedures / code / example on integrating FFmpeg on Android / StageFright?

2. Can you please guide me on how can I use this library for multimedia playback?

3. I have a requirement where I have already audio and video transport streams, which I need to feed to FFmpeg and get it decoded / rendered. How can I do this on Android, since IOMX APIs are OMX based and cannot plug-in FFmpeg here?

4. Also I could not find documentation on the FFmpeg APIs which need to be used for playback.

FFmpeg on Android

I&#39;m trying to get a Spinner to load up with no selected value. Once the user selects a value it then takes them to another page. 

This is proving to be a problem because at present, the page just loads straight away before the user gets a choice to choose.

My spinner class is set up the same way as Google&#39;s: http://developer.android.com/resources/tutorials/views/hello-spinner.html

So basically, is it possible have a spinner that loads with nothing selected because at present, it loads the first item in my string array.


How to set Spinner default value to null?

This is confusing me:

As far as I have read, a view with setVisibility(View.GONE); should not receive any more touch- or click events.
My layout has two parts, which will be visible or gone so that only one of them is visible and usable at a time but View.GONE doesn&#39;t do the trick.
I can&#39;t see the GONE view, as expected, but it still reacts to onClick (and consumes the event the other view should get).

Can you help me?

_Maybe of interest:
When I start my project one view is GONE, the other visible. This time it will work as expected (the GONE view is basically ignored), but after setting View.GONE through the code it&#39;ll stop working._

android View with View.GONE still receives onTouch and onClick

The new documentation on [ProGuard for Android][1] says to add a line to the default.properties file in the project home directory. However, on opening this file, I read at the top: 

    # This file is automatically generated by Android Tools. 
    # Do not modify this file -- YOUR CHANGES WILL BE ERASED! 

Am I missing something?

Also, is there a way to enable ProGuard only for a production build from Eclipse (i.e., when exporting the finished product)?


  [1]: http://developer.android.com/guide/developing/tools/proguard.html

Enabling ProGuard in Eclipse for Android

A simple question, relating to the default &#39;home&#39; directory when an app writes to the internal memory. By default, any files created are placed by the OS (2.2) in:

    /data/data/your.package/files

When reading in files, the same default is used, when keeping in proper context via `openFileInput()`, `openFileOutput()`.  But if I need to check file existence, for instance, using the File class, I need to specify the whole path in the constructor.

I see there are `Environment.getDataDirectory()` (returns `/data`), `Environment.getRootDirectory()` (returns `/system`), etc, but nothing related to getting the app&#39;s &#39;home&#39; directory.

It&#39;s not a huge deal, but I&#39;d rather not hard-code the full path into my App for File to use (say the package name changes, say the path changes in a future OS release) if there is some way to reference the app&#39;s &#39;home&#39; directory programmatically.

Android Get Application&#39;s &#39;Home&#39; Data Directory

What operations in Java are considered atomic?

In a thread, I create some `System.Threading.Task` and start each task.

When I do a `.Abort()` to kill the thread, the tasks are not aborted.

How can I transmit the `.Abort()` to my tasks ?

How do I abort/cancel TPL Tasks?

Is it true that C++0x will come without semaphores? There are already some questions on Stack Overflow regarding the use of semaphores. I use them (posix semaphores) all the time to let a thread wait for some event in another thread:

    void thread0(...)
    {
      doSomething0();
    
      event1.wait();

      ...
    }

    void thread1(...)
    {
      doSomething1();
    
      event1.post();

      ...
    }

If I would do that with a mutex:

    void thread0(...)
    {
      doSomething0();
    
      event1.lock(); event1.unlock();

      ...
    }

    void thread1(...)
    {
      event1.lock();

      doSomethingth1();
    
      event1.unlock();

      ...
    }

Problem: It&#39;s ugly and it&#39;s not guaranteed that thread1 locks the mutex first (Given that the same thread should lock and unlock a mutex, you also can&#39;t lock event1 before thread0 and thread1 started).

So since boost doesn&#39;t have semaphores either, what is the simplest way to achieve the above?

C++0x has no semaphores? How to synchronize threads?

It seems that in November, Apple updated both the [NSManagedObjectContext Class Reference][1] and the [Core Data Programming Guide][2] documents to explicitly bless serial GCD Dispatch Queues and  NSOperationQueues as acceptable mechanisms for synchronising access to a `NSManagedObjectContext`. But their advice seems ambiguous and possibly contradictory, and I want to make sure I&#39;ve understood it properly.

Previously the accepted wisdom seemed to be that a `NSManagedObjectContext` could only be accessed from the thread that created it, and that using a serial queue for synchronisation was not sufficient; although serial queues only perform one operation at a time, these operations can potentially be scheduled on different threads, and a MOC doesn&#39;t like that.

But now, from the programming guide, we have:
&gt; You can use threads, serial operation queues, or dispatch queues for concurrency. For the sake of conciseness, this article uses “thread” throughout to refer to any of these.

So far, so good (although their conflation of threads and queues is unhelpful). So I can safely use a single context per (serial) queue, instead of one per operation/block, right? Apple even has a visual depiction of this in the Core Data WWDC sessions.

But... where do you create the context for the queue? In the `NSManagedObjectContext` documentation, Apple state:
&gt; [A context] assumes the default owner is the thread or queue that allocated it—this is determined by the thread that calls its init method. You should not, therefore, initialize a context on one thread then pass it to a different thread.

So now we have the idea of a `NSManagedObjectContext` needing to know who its owner is. I&#39;m assuming this means that the first operation to be executed in the queue should create the MOC and save a reference to it for the remaining operations to use.

Is this right? The only reason I&#39;m hesitant is that the `NSManagedObjectContext` article goes on to say:
&gt; Instead, you should pass a reference to a persistent store coordinator and have the receiving thread/queue create a new context derived from that. If you use NSOperation, you must create the context in main (for a serial queue) or start (for a concurrent queue).

Apple now seem to be conflating operations with the queues that schedule their execution. This does my head in, and makes me wonder if they really do want you to just create a new MOC for every operation after all. What am I missing?

  [1]: http://developer.apple.com/library/mac/#documentation/cocoa/Reference/CoreDataFramework/Classes/NSManagedObjectContext_Class/NSManagedObjectContext.html%23//apple_ref/doc/uid/TP30001182-DontLinkElementID_1
  [2]: http://developer.apple.com/library/mac/documentation/cocoa/Conceptual/CoreData/Articles/cdConcurrency.html#//apple_ref/doc/uid/TP40003385-SW1

What does Apple mean when they say that a NSManagedObjectContext is owned by the thread or queue that created it?

I have a worker thread that sits in the background, processing messages. Something like this:

    class Worker extends Thread {

        public volatile Handler handler; // actually private, of course

        public void run() {
            Looper.prepare();
            mHandler = new Handler() { // the Handler hooks up to the current Thread
                public boolean handleMessage(Message msg) {
                    // ...
                }
            };
            Looper.loop();
        }
    }

From the main thread (UI thread, not that it matters) I would like to do something like this:

    Worker worker = new Worker();
    worker.start();
    worker.handler.sendMessage(...);

The trouble is that this sets me up for a beautiful race condition: at the time `worker.handler` is read, there is no way to be sure that the worker thread has already assigned to this field!

I cannot simply create the `Handler` from the `Worker`&#39;s constructor, because the constructor runs on the main thread, so the `Handler` will associate itself with the wrong thread.

This hardly seems like an uncommon scenario. I can come up with several workarounds, all of them ugly:

1. Something like this:

        class Worker extends Thread {

            public volatile Handler handler; // actually private, of course
    
            public void run() {
                Looper.prepare();
                mHandler = new Handler() { // the Handler hooks up to the current Thread
                    public boolean handleMessage(Message msg) {
                        // ...
                    }
                };
                notifyAll(); // &lt;- ADDED
                Looper.loop();
            }
        }

    And from the main thread:

        Worker worker = new Worker();
        worker.start();
        worker.wait(); // &lt;- ADDED
        worker.handler.sendMessage(...);

    But this is not reliable either: if the `notifyAll()` happens before the `wait()`, then we&#39;ll never be woken up!

2. Passing an initial `Message` to the `Worker`&#39;s constructor, having the `run()` method post it. An ad-hoc solution, won&#39;t work for multiple messages, or if we don&#39;t want to send it right away but soon after.

3. Busy-waiting until the `handler` field is no longer `null`. Yep, a last resort...

I would like to create a `Handler` and `MessageQueue` on behalf of the `Worker` thread, but this does not seem to be possible. What is the most elegant way out of this?

Content Type	Original Author	Original Content on Stackoverflow
Question	ram	View Question on Stackoverflow
Solution 1 - Android	RoflcoptrException	View Answer on Stackoverflow
Solution 2 - Android	Endian Ogino	View Answer on Stackoverflow
Solution 3 - Android	mbejda	View Answer on Stackoverflow

Threading Example in Android

Android Problem Overview

Android Solutions

Solution 1 - Android

Solution 2 - Android

Solution 3 - Android

How can I get scrollbars on Picturebox

entity framework Unable to load the specified metadata resource

Attributions