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  • Java Thread wait() => blocked?

    - by Chris
    According to http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Thread.State.html calling wait() will result a thread to go in BLOCKED state. However this piece of code will result (after being called) in a Thread in WAITING State. class bThread extends Thread { public synchronized void run() { try { wait(); } catch (InterruptedException e) { e.printStackTrace(); } } } Have I got something wrong? Can anybody explain this behaviour to me? Any help would be appreciated!

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  • Android Java Eclipse Intent with 2 Projects

    - by user3793685
    Good day! I have 2 Projects in my Eclipse. MainActivity1 and MainActivity2 are the names of the activities. The MainActivity2 is connected to the MainActivity1 via Project in the properties of the MainActivity1. So far, I can call the package of the MainActivity2 from the MainActivity1. Now, below are my problem: I have a button in MainActivity1. What I want to do is after I click on the button in the MainActivity1, it runs the MainActivity2 project and some variables will be passed on to the MainActivity2. I've been searching in google for a while now and I couldn't get the right keyword for it. I've checked some of the questions here in StackOverflow but I'm unable to locate the problem similar to mine with calling and running the MainActivity2 class from the MainActivity1.java I'm a noob in Android Java but have knowledge in other OOP. Any tips will be a great help. Thanks

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  • Java Web Application

    - by Mark R
    I am interested in creating a simple web application that will take in user input, convert it to an XML file and send the file to a database. Coding wise I feel I am okay, it is just the general setup and what implementation to use I am a bit unsure of. At the moment I have a JSP page containing a form, the user fills out the form and on submit a get method is sent to a servlet, in the servlet doGet() method the servlet is instantiating a java object and passing it the user inputted data. The java object then writes that data to an XML file and sends it to the database via REST. All I would be interested to know is if this the standard/optimal way of creating such a web application. Any and all feedback is appreciated. Thanks

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  • Load a dll library on Java

    - by crimson_king
    I need to load a library written in C on java. I have only dlls and header files. Since I didn't understand how to translate pointers or other derivated types from JNI documentation I tried to use an automating tool for this, gluegen and SWIG, but I couldn't manage on how to use them. I tried to create an interface file for SWIG but it only gives errors. Is there an example on how to load a dll to a java program using ANY tool that works and can generate translated C function and types from .h files ?

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  • Getting value in ZK by passing from java

    - by Thida
    I could not take the value that I pass from JAVA code in ZK Spreadsheet (http://www.zkoss.org) file. Here are what I am doing: In java side I call the .zul file String filenames = "test.txt"; htmlPane.setContentsURL("preview.zul?filename=" + filename); In preview.zul file < zk < zscript < ![CDATA[ System.out.println(execution.getArg().get("filename")); ]] < /zscript < zk The the result is NUll Could you help how to write the correct script? Thanks,

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  • Comparing Java enum members: == or equals() ?

    - by Bears will eat you
    I know that Java enums are compiled to classes with private constructors and a bunch of public static members. When comparing two members of a given enum, I've always used .equals(), e.g. public useEnums(SomeEnum a) { if(a.equals(SomeEnum.SOME_ENUM_VALUE)) { ... } ... } However, I just came across come code that uses the equals operator == instead: public useEnums2(SomeEnum a) { if(a == SomeEnum.SOME_ENUM_VALUE) { ... } ... } I've been programming in Java for 5+ years, and I thought I understood difference between the two - but I'm still scratching my head at which one is more correct. Which operator is the one I should be using?

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  • Java Basics: create class object

    - by user1767853
    In C++: class Rectangle { int x, y; public: void set_values (int,int); int area () {return (x*y);} }; int main () { Rectangle rect; rect.set_values (3,4); } In Java: class Rectangle { int x, y; void set_values (int x,int y); int area () {return (x*y);} } public static void main(String[] args) { Rectangle rect=new Rectangle(3,4); } In C++ compiler will create rect object & reserve memory 4 bytes. I want to know How Java is creating object?

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  • Android - doInBackground() error in AsyncTask

    - by AimanB
    What my app here basically does is it captures a photo or import from gallery, and when the Upload button is pressed, the image will be uploaded to a localhost server. Before I implemented AsyncTask into the process, it doesn't have any problem uploading whatsoever. Now that I've put AsyncTask, everything went wrong. I don't know which part that I do wrong in this phase. This is what logcat shows when I try to upload an image file: 10-28 17:23:25.989: E/AndroidRuntime(3356): FATAL EXCEPTION: AsyncTask #5 10-28 17:23:25.989: E/AndroidRuntime(3356): java.lang.RuntimeException: An error occured while executing doInBackground() 10-28 17:23:25.989: E/AndroidRuntime(3356): at android.os.AsyncTask$3.done(AsyncTask.java:299) 10-28 17:23:25.989: E/AndroidRuntime(3356): at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:352) 10-28 17:23:25.989: E/AndroidRuntime(3356): at java.util.concurrent.FutureTask.setException(FutureTask.java:219) 10-28 17:23:25.989: E/AndroidRuntime(3356): at java.util.concurrent.FutureTask.run(FutureTask.java:239) 10-28 17:23:25.989: E/AndroidRuntime(3356): at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230) 10-28 17:23:25.989: E/AndroidRuntime(3356): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080) 10-28 17:23:25.989: E/AndroidRuntime(3356): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573) 10-28 17:23:25.989: E/AndroidRuntime(3356): at java.lang.Thread.run(Thread.java:856) 10-28 17:23:25.989: E/AndroidRuntime(3356): Caused by: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare() 10-28 17:23:25.989: E/AndroidRuntime(3356): at android.os.Handler.<init>(Handler.java:197) 10-28 17:23:25.989: E/AndroidRuntime(3356): at android.os.Handler.<init>(Handler.java:111) 10-28 17:23:25.989: E/AndroidRuntime(3356): at android.widget.Toast$TN.<init>(Toast.java:324) 10-28 17:23:25.989: E/AndroidRuntime(3356): at android.widget.Toast.<init>(Toast.java:91) 10-28 17:23:25.989: E/AndroidRuntime(3356): at android.widget.Toast.makeText(Toast.java:238) 10-28 17:23:25.989: E/AndroidRuntime(3356): at com.aiman.webshopper.UploadImageActivity$1execMultiPostAsync.doInBackground(UploadImageActivity.java:268) 10-28 17:23:25.989: E/AndroidRuntime(3356): at com.aiman.webshopper.UploadImageActivity$1execMultiPostAsync.doInBackground(UploadImageActivity.java:1) 10-28 17:23:25.989: E/AndroidRuntime(3356): at android.os.AsyncTask$2.call(AsyncTask.java:287) 10-28 17:23:25.989: E/AndroidRuntime(3356): at java.util.concurrent.FutureTask.run(FutureTask.java:234) This is my code for the Upload activity: public class UploadImageActivity extends Activity implements OnItemSelectedListener { InputStream inputStream; private ImageView imageView; String the_string_response; private static final int SELECT_PICTURE = 0; private static final int CAMERA_REQUEST = 1888; private static final String SERVER_UPLOAD_URI = "...myserver.php"; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_upload_image); imageView = (ImageView) findViewById(R.id.imgUpload); } public void capturePhoto(View view) { Intent cameraIntent = new Intent( android.provider.MediaStore.ACTION_IMAGE_CAPTURE); File f = new File(android.os.Environment.getExternalStorageDirectory(), "temp.jpg"); cameraIntent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(f)); startActivityForResult(cameraIntent, CAMERA_REQUEST); } public void pickPhoto(View view) { // TODO: launch the photo picker Intent intent = new Intent(); intent.setType("image/*"); intent.setAction(Intent.ACTION_GET_CONTENT); startActivityForResult(Intent.createChooser(intent, "Select Picture"), SELECT_PICTURE); } @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { super.onActivityResult(requestCode, resultCode, data); if (requestCode == CAMERA_REQUEST && resultCode == RESULT_OK) { File f = new File(Environment.getExternalStorageDirectory() .toString()); for (File temp : f.listFiles()) { if (temp.getName().equals("temp.jpg")) { f = temp; break; } } try { BitmapFactory.Options bitmapOptions = new BitmapFactory.Options(); Bitmap bitmap = BitmapFactory.decodeFile(f.getAbsolutePath(), bitmapOptions); imageView.setImageBitmap(bitmap); String path = android.os.Environment .getExternalStorageDirectory() + File.separator + "Phoenix" + File.separator + "default"; f.delete(); OutputStream outFile = null; File file = new File(path, String.valueOf(System .currentTimeMillis()) + ".jpg"); try { outFile = new FileOutputStream(file); bitmap.compress(Bitmap.CompressFormat.JPEG, 85, outFile); outFile.flush(); outFile.close(); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } catch (Exception e) { e.printStackTrace(); } } catch (Exception e) { e.printStackTrace(); } } if (requestCode == SELECT_PICTURE && resultCode == RESULT_OK) { Bitmap bitmap = getPath(data.getData()); imageView.setImageBitmap(bitmap); } } private Bitmap getPath(Uri uri) { String[] projection = { MediaStore.Images.Media.DATA }; Cursor cursor = getContentResolver().query(uri, projection, null, null, null); int column_index = cursor.getColumnIndexOrThrow(projection[0]); cursor.moveToFirst(); String filePath = cursor.getString(column_index); cursor.close(); // Convert file path into bitmap image using below line. Bitmap bitmap = BitmapFactory.decodeFile(filePath); return bitmap; } public void uploadPhoto(View view) { try { executeMultipartPost(); } catch (Exception e) { e.printStackTrace(); } } public void executeMultipartPost() throws Exception { class execMultiPostAsync extends AsyncTask<String, Void, String>{ @Override protected String doInBackground(String... params){ // Choose image here BitmapDrawable drawable = (BitmapDrawable) imageView.getDrawable(); Bitmap bitmap = drawable.getBitmap(); ByteArrayOutputStream stream = new ByteArrayOutputStream(); bitmap.compress(Bitmap.CompressFormat.JPEG, 50, stream); // compress to // which // format // you want. byte[] byte_arr = stream.toByteArray(); String image_str = Base64.encodeBytes(byte_arr); ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(); nameValuePairs.add(new BasicNameValuePair("image", image_str)); try { HttpClient httpclient = new DefaultHttpClient(); /* * HttpPost(parameter): Server URI */ HttpPost httppost = new HttpPost(SERVER_UPLOAD_URI); httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs)); HttpResponse response = httpclient.execute(httppost); the_string_response = convertResponseToString(response); } catch (Exception e) { Toast.makeText(UploadImageActivity.this, "ERROR " + e.getMessage(), Toast.LENGTH_LONG).show(); System.out.println("Error in http connection " + e.toString()); } return the_string_response; } @Override protected void onPostExecute(String result) { super.onPostExecute(result); Toast.makeText(UploadImageActivity.this, "Response " + result, Toast.LENGTH_LONG) .show(); } public String convertResponseToString(HttpResponse response) throws IllegalStateException, IOException { String res = ""; StringBuffer buffer = new StringBuffer(); inputStream = response.getEntity().getContent(); int contentLength = (int) response.getEntity().getContentLength(); // getting // content // lengt Toast.makeText(UploadImageActivity.this, "contentLength : " + contentLength, Toast.LENGTH_LONG).show(); if (contentLength < 0) { } else { byte[] data = new byte[512]; int len = 0; try { while (-1 != (len = inputStream.read(data))) { buffer.append(new String(data, 0, len)); // converting to // string and // appending to // stringbuffer } } catch (IOException e) { e.printStackTrace(); } try { inputStream.close(); // closing the stream } catch (IOException e) { e.printStackTrace(); } res = buffer.toString(); // converting stringbuffer to string Toast.makeText(UploadImageActivity.this, "Result : " + res, Toast.LENGTH_LONG).show(); // System.out.println("Response => " + // EntityUtils.toString(response.getEntity())); } return res; } } execMultiPostAsync exec = new execMultiPostAsync(); exec.execute(); } } Can someone please check if I put the AsyncTask task correctly in this activity? I think I've made a mistake somewhere.

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  • ActiveMQ - "Cannot send, channel has already failed" every 2 seconds?

    - by quanta
    ActiveMQ 5.7.0 In the activemq.log, I'm seeing this exception every 2 seconds: 2013-11-05 13:00:52,374 | DEBUG | Transport Connection to: tcp://127.0.0.1:37501 failed: org.apache.activemq.transport.InactivityIOException: Cannot send, channel has already failed: tcp://127.0.0.1:37501 | org.apache.activemq.broker.TransportConnection.Transport | Async Exception Handler org.apache.activemq.transport.InactivityIOException: Cannot send, channel has already failed: tcp://127.0.0.1:37501 at org.apache.activemq.transport.AbstractInactivityMonitor.doOnewaySend(AbstractInactivityMonitor.java:282) at org.apache.activemq.transport.AbstractInactivityMonitor.oneway(AbstractInactivityMonitor.java:271) at org.apache.activemq.transport.TransportFilter.oneway(TransportFilter.java:85) at org.apache.activemq.transport.WireFormatNegotiator.oneway(WireFormatNegotiator.java:104) at org.apache.activemq.transport.MutexTransport.oneway(MutexTransport.java:68) at org.apache.activemq.broker.TransportConnection.dispatch(TransportConnection.java:1312) at org.apache.activemq.broker.TransportConnection.processDispatch(TransportConnection.java:838) at org.apache.activemq.broker.TransportConnection.iterate(TransportConnection.java:873) at org.apache.activemq.thread.PooledTaskRunner.runTask(PooledTaskRunner.java:129) at org.apache.activemq.thread.PooledTaskRunner$1.run(PooledTaskRunner.java:47) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) at java.lang.Thread.run(Thread.java:662) Due to this keyword InactivityIOException, the first thing comes to my mind is InactivityMonitor, but the strange thing is MaxInactivityDuration=30000: 2013-11-05 13:11:02,672 | DEBUG | Sending: WireFormatInfo { version=9, properties={MaxFrameSize=9223372036854775807, CacheSize=1024, CacheEnabled=true, SizePrefixDisabled=false, MaxInactivityDurationInitalDelay=10000, TcpNoDelayEnabled=true, MaxInactivityDuration=30000, TightEncodingEnabled=true, StackTraceEnabled=true}, magic=[A,c,t,i,v,e,M,Q]} | org.apache.activemq.transport.WireFormatNegotiator | ActiveMQ BrokerService[localhost] Task-2 Moreover, I also didn't see something like this: No message received since last read check for ... or: Channel was inactive for too (30000) long Do a netstat, I see these connections in TIME_WAIT state: tcp 0 0 127.0.0.1:38545 127.0.0.1:61616 TIME_WAIT - tcp 0 0 127.0.0.1:38544 127.0.0.1:61616 TIME_WAIT - tcp 0 0 127.0.0.1:38522 127.0.0.1:61616 TIME_WAIT - Here're the output when running tcpdump: Internet Protocol Version 4, Src: 127.0.0.1 (127.0.0.1), Dst: 127.0.0.1 (127.0.0.1) Version: 4 Header length: 20 bytes Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00: Not-ECT (Not ECN-Capable Transport)) 0000 00.. = Differentiated Services Codepoint: Default (0x00) .... ..00 = Explicit Congestion Notification: Not-ECT (Not ECN-Capable Transport) (0x00) Total Length: 296 Identification: 0x7b6a (31594) Flags: 0x02 (Don't Fragment) 0... .... = Reserved bit: Not set .1.. .... = Don't fragment: Set ..0. .... = More fragments: Not set Fragment offset: 0 Time to live: 64 Protocol: TCP (6) Header checksum: 0xc063 [correct] [Good: True] [Bad: False] Source: 127.0.0.1 (127.0.0.1) Destination: 127.0.0.1 (127.0.0.1) Transmission Control Protocol, Src Port: 61616 (61616), Dst Port: 54669 (54669), Seq: 1, Ack: 2, Len: 244 Source port: 61616 (61616) Destination port: 54669 (54669) [Stream index: 11] Sequence number: 1 (relative sequence number) [Next sequence number: 245 (relative sequence number)] Acknowledgement number: 2 (relative ack number) Header length: 32 bytes Flags: 0x018 (PSH, ACK) 000. .... .... = Reserved: Not set ...0 .... .... = Nonce: Not set .... 0... .... = Congestion Window Reduced (CWR): Not set .... .0.. .... = ECN-Echo: Not set .... ..0. .... = Urgent: Not set .... ...1 .... = Acknowledgement: Set .... .... 1... = Push: Set .... .... .0.. = Reset: Not set .... .... ..0. = Syn: Not set .... .... ...0 = Fin: Not set Window size value: 256 [Calculated window size: 32768] [Window size scaling factor: 128] Checksum: 0xff1c [validation disabled] [Good Checksum: False] [Bad Checksum: False] Options: (12 bytes) No-Operation (NOP) No-Operation (NOP) Timestamps: TSval 2304161892, TSecr 2304161891 Kind: Timestamp (8) Length: 10 Timestamp value: 2304161892 Timestamp echo reply: 2304161891 [SEQ/ACK analysis] [Bytes in flight: 244] Constrained Application Protocol, TID: 240, Length: 244 00.. .... = Version: 0 ..00 .... = Type: Confirmable (0) .... 0000 = Option Count: 0 Code: Unknown (0) Transaction ID: 240 Payload Content-Type: text/plain (default), Length: 240, offset: 4 Line-based text data: text/plain [truncated] \001ActiveMQ\000\000\000\t\001\000\000\000<DE>\000\000\000\t\000\fMaxFrameSize\006\177<FF><FF><FF><FF> <FF><FF><FF>\000\tCacheSize\005\000\000\004\000\000\fCacheEnabled\001\001\000\022SizePrefixDisabled\001\000\000 MaxInactivityDurationInitalDelay\006\ It is very likely a tcp port check. This is what I see when trying telnet from another host: 2013-11-05 16:12:41,071 | DEBUG | Transport Connection to: tcp://10.8.20.9:46775 failed: java.io.EOFException | org.apache.activemq.broker.TransportConnection.Transport | ActiveMQ Transport: tcp:///10.8.20.9:46775@61616 java.io.EOFException at java.io.DataInputStream.readInt(DataInputStream.java:375) at org.apache.activemq.openwire.OpenWireFormat.unmarshal(OpenWireFormat.java:275) at org.apache.activemq.transport.tcp.TcpTransport.readCommand(TcpTransport.java:229) at org.apache.activemq.transport.tcp.TcpTransport.doRun(TcpTransport.java:221) at org.apache.activemq.transport.tcp.TcpTransport.run(TcpTransport.java:204) at java.lang.Thread.run(Thread.java:662) 2013-11-05 16:12:41,071 | DEBUG | Transport Connection to: tcp://10.8.20.9:46775 failed: org.apache.activemq.transport.InactivityIOException: Cannot send, channel has already failed: tcp://10.8.20.9:46775 | org.apache.activemq.broker.TransportConnection.Transport | Async Exception Handler org.apache.activemq.transport.InactivityIOException: Cannot send, channel has already failed: tcp://10.8.20.9:46775 at org.apache.activemq.transport.AbstractInactivityMonitor.doOnewaySend(AbstractInactivityMonitor.java:282) at org.apache.activemq.transport.AbstractInactivityMonitor.oneway(AbstractInactivityMonitor.java:271) at org.apache.activemq.transport.TransportFilter.oneway(TransportFilter.java:85) at org.apache.activemq.transport.WireFormatNegotiator.oneway(WireFormatNegotiator.java:104) at org.apache.activemq.transport.MutexTransport.oneway(MutexTransport.java:68) at org.apache.activemq.broker.TransportConnection.dispatch(TransportConnection.java:1312) at org.apache.activemq.broker.TransportConnection.processDispatch(TransportConnection.java:838) at org.apache.activemq.broker.TransportConnection.iterate(TransportConnection.java:873) at org.apache.activemq.thread.PooledTaskRunner.runTask(PooledTaskRunner.java:129) at org.apache.activemq.thread.PooledTaskRunner$1.run(PooledTaskRunner.java:47) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) at java.lang.Thread.run(Thread.java:662) 2013-11-05 16:12:41,071 | DEBUG | Unregistering MBean org.apache.activemq:BrokerName=localhost,Type=Connection,ConnectorName=ope nwire,ViewType=address,Name=tcp_//10.8.20.9_46775 | org.apache.activemq.broker.jmx.ManagementContext | ActiveMQ Transport: tcp:/ //10.8.20.9:46775@61616 2013-11-05 16:12:41,073 | DEBUG | Stopping connection: tcp://10.8.20.9:46775 | org.apache.activemq.broker.TransportConnection | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,073 | DEBUG | Stopping transport tcp:///10.8.20.9:46775@61616 | org.apache.activemq.transport.tcp.TcpTranspo rt | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,073 | DEBUG | Initialized TaskRunnerFactory[ActiveMQ Task] using ExecutorService: java.util.concurrent.Threa dPoolExecutor@23cc2a28 | org.apache.activemq.thread.TaskRunnerFactory | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,074 | DEBUG | Closed socket Socket[addr=/10.8.20.9,port=46775,localport=61616] | org.apache.activemq.transpo rt.tcp.TcpTransport | ActiveMQ Task-1 2013-11-05 16:12:41,074 | DEBUG | Forcing shutdown of ExecutorService: java.util.concurrent.ThreadPoolExecutor@23cc2a28 | org.apache.activemq.util.ThreadPoolUtils | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,074 | DEBUG | Stopped transport: tcp://10.8.20.9:46775 | org.apache.activemq.broker.TransportConnection | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,074 | DEBUG | Connection Stopped: tcp://10.8.20.9:46775 | org.apache.activemq.broker.TransportConnection | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,902 | DEBUG | Sending: WireFormatInfo { version=9, properties={MaxFrameSize=9223372036854775807, CacheSize=1024, CacheEnabled=true, SizePrefixDisabled=false, MaxInactivityDurationInitalDelay=10000, TcpNoDelayEnabled=true, MaxInactivityDuration=30000, TightEncodingEnabled=true, StackTraceEnabled=true}, magic=[A,c,t,i,v,e,M,Q]} | org.apache.activemq.transport.WireFormatNegotiator | ActiveMQ BrokerService[localhost] Task-5 So the question is: how can I find out the process that is trying to connect to my ActiveMQ (from localhost) every 2 seconds?

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  • What are developer's problems with helpful error messages?

    - by Moo-Juice
    It continue to astounds me that, in this day and age, products that have years of use under their belt, built by teams of professionals, still to this day - fail to provide helpful error messages to the user. In some cases, the addition of just a little piece of extra information could save a user hours of trouble. A program that generates an error, generated it for a reason. It has everything at its disposal to inform the user as much as it can, why something failed. And yet it seems that providing information to aid the user is a low-priority. I think this is a huge failing. One example is from SQL Server. When you try and restore a database that is in use, it quite rightly won't let you. SQL Server knows what processes and applications are accessing it. Why can't it include information about the process(es) that are using the database? I know not everyone passes an Applicatio_Name attribute on their connection string, but even a hint about the machine in question could be helpful. Another candidate, also SQL Server (and mySQL) is the lovely string or binary data would be truncated error message and equivalents. A lot of the time, a simple perusal of the SQL statement that was generated and the table shows which column is the culprit. This isn't always the case, and if the database engine picked up on the error, why can't it save us that time and just tells us which damned column it was? On this example, you could argue that there may be a performance hit to checking it and that this would impede the writer. Fine, I'll buy that. How about, once the database engine knows there is an error, it does a quick comparison after-the-fact, between values that were going to be stored, versus the column lengths. Then display that to the user. ASP.NET's horrid Table Adapters are also guilty. Queries can be executed and one can be given an error message saying that a constraint somewhere is being violated. Thanks for that. Time to compare my data model against the database, because the developers are too lazy to provide even a row number, or example data. (For the record, I'd never use this data-access method by choice, it's just a project I have inherited!). Whenever I throw an exception from my C# or C++ code, I provide everything I have at hand to the user. The decision has been made to throw it, so the more information I can give, the better. Why did my function throw an exception? What was passed in, and what was expected? It takes me just a little longer to put something meaningful in the body of an exception message. Hell, it does nothing but help me whilst I develop, because I know my code throws things that are meaningful. One could argue that complicated exception messages should not be displayed to the user. Whilst I disagree with that, it is an argument that can easily be appeased by having a different level of verbosity depending on your build. Even then, the users of ASP.NET and SQL Server are not your typical users, and would prefer something full of verbosity and yummy information because they can track down their problems faster. Why to developers think it is okay, in this day and age, to provide the bare minimum amount of information when an error occurs? It's 2011 guys, come on.

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  • Combining HBase and HDFS results in Exception in makeDirOnFileSystem

    - by utrecht
    Introduction An attempt to combine HBase and HDFS results in the following: 2014-06-09 00:15:14,777 WARN org.apache.hadoop.hbase.HBaseFileSystem: Create Dir ectory, retries exhausted 2014-06-09 00:15:14,780 FATAL org.apache.hadoop.hbase.master.HMaster: Unhandled exception. Starting shutdown. java.io.IOException: Exception in makeDirOnFileSystem at org.apache.hadoop.hbase.HBaseFileSystem.makeDirOnFileSystem(HBaseFile System.java:136) at org.apache.hadoop.hbase.master.MasterFileSystem.checkRootDir(MasterFi leSystem.java:428) at org.apache.hadoop.hbase.master.MasterFileSystem.createInitialFileSyst emLayout(MasterFileSystem.java:148) at org.apache.hadoop.hbase.master.MasterFileSystem.<init>(MasterFileSyst em.java:133) at org.apache.hadoop.hbase.master.HMaster.finishInitialization(HMaster.j ava:572) at org.apache.hadoop.hbase.master.HMaster.run(HMaster.java:432) at java.lang.Thread.run(Thread.java:744) Caused by: org.apache.hadoop.security.AccessControlException: Permission denied: user=hbase, access=WRITE, inode="/":vagrant:supergroup:drwxr-xr-x at org.apache.hadoop.hdfs.server.namenode.FSPermissionChecker.check(FSPe rmissionChecker.java:224) at org.apache.hadoop.hdfs.server.namenode.FSPermissionChecker.check(FSPe rmissionChecker.java:204) at org.apache.hadoop.hdfs.server.namenode.FSPermissionChecker.checkPermi ssion(FSPermissionChecker.java:149) at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkPermission(F SNamesystem.java:4891) at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkPermission(F SNamesystem.java:4873) at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkAncestorAcce ss(FSNamesystem.java:4847) at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.mkdirsInternal(FS Namesystem.java:3192) at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.mkdirsInt(FSNames ystem.java:3156) at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.mkdirs(FSNamesyst em.java:3137) at org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.mkdirs(NameN odeRpcServer.java:669) at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolServerSideTra nslatorPB.mkdirs(ClientNamenodeProtocolServerSideTranslatorPB.java:419) at org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos$Cl ientNamenodeProtocol$2.callBlockingMethod(ClientNamenodeProtocolProtos.java:4497 0) at org.apache.hadoop.ipc.ProtobufRpcEngine$Server$ProtoBufRpcInvoker.cal l(ProtobufRpcEngine.java:453) at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:1002) at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1752) at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1748) at java.security.AccessController.doPrivileged(Native Method) at javax.security.auth.Subject.doAs(Subject.java:422) at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInforma tion.java:1438) at org.apache.hadoop.ipc.Server$Handler.run(Server.java:1746) at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstruct orAccessorImpl.java:62) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingC onstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:408) at org.apache.hadoop.ipc.RemoteException.instantiateException(RemoteExce ption.java:90) at org.apache.hadoop.ipc.RemoteException.unwrapRemoteException(RemoteExc eption.java:57) at org.apache.hadoop.hdfs.DFSClient.primitiveMkdir(DFSClient.java:2153) at org.apache.hadoop.hdfs.DFSClient.mkdirs(DFSClient.java:2122) at org.apache.hadoop.hdfs.DistributedFileSystem.mkdirs(DistributedFileSy stem.java:545) at org.apache.hadoop.fs.FileSystem.mkdirs(FileSystem.java:1915) at org.apache.hadoop.hbase.HBaseFileSystem.makeDirOnFileSystem(HBaseFile System.java:129) ... 6 more while configuration and system settings are as follows: [vagrant@localhost hadoop-hdfs]$ hadoop fs -ls hdfs://localhost/ Found 1 items -rw-r--r-- 3 vagrant supergroup 1010827264 2014-06-08 19:01 hdfs://localhost/u buntu-14.04-desktop-amd64.iso [vagrant@localhost hadoop-hdfs]$ /etc/hadoop/conf/core-site.xml <configuration> <property> <name>fs.defaultFS</name> <value>hdfs://localhost:8020</value> </property> </configuration> /etc/hbase/conf/hbase-site.xml <configuration> <property> <name>hbase.rootdir</name> <value>hdfs://localhost:8020/hbase</value> </property> <property> <name>hbase.cluster.distributed</name> <value>true</value> </property> </configuration> /etc/hadoop/conf/hdfs-site.xml <configuration> <property> <name>dfs.name.dir</name> <value>/var/lib/hadoop-hdfs/cache</value> </property> <property> <name>dfs.data.dir</name> <value>/tmp/hellodatanode</value> </property> </configuration> NameNode directory permissions [vagrant@localhost hadoop-hdfs]$ ls -ltr /var/lib/hadoop-hdfs/cache total 8 -rwxrwxrwx. 1 hbase hdfs 15 Jun 8 23:43 in_use.lock drwxrwxrwx. 2 hbase hdfs 4096 Jun 8 23:43 current [vagrant@localhost hadoop-hdfs]$ HMaster is able to start if fs.defaultFS property has been commented in core-site.xml NameNode is listening [vagrant@localhost hadoop-hdfs]$ netstat -nato | grep 50070 tcp 0 0 0.0.0.0:50070 0.0.0.0:* LIST EN off (0.00/0/0) tcp 0 0 33.33.33.33:50070 33.33.33.1:57493 ESTA BLISHED off (0.00/0/0) and accessible by navigating to http://33.33.33.33:50070/dfshealth.jsp. Question How to solve makeDirOnFileSystem exception and let HBase connect to HDFS?

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  • Python Forgiveness vs. Permission and Duck Typing

    - by darkfeline
    In Python, I often hear that it is better to "beg forgiveness" (exception catching) instead of "ask permission" (type/condition checking). In regards to enforcing duck typing in Python, is this try: x = foo.bar except AttributeError: pass else: do(x) better or worse than if hasattr(foo, "bar"): do(foo.bar) else: pass in terms of performance, readability, "pythonic", or some other important factor?

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  • Zend - unable to catch exception [closed]

    - by coder3
    This still throw an uncaught exception.. Any insight why this isn't working? protected function login() { $cart = $this->getHelper('GetCurrentCart'); $returnValue = false; if ($this->view->form->isValid($this->_getAllParams())) { $values = $this->view->form->getValues(); try { $this->goreg = $this->goregFactory->create($this->config->goreg->service_url); if ($this->goreg->login($values['username'], $values['password']) && $this->goregSession->isLoggedIn()) { $returnValue = true; } else { echo 'success 1'; } } catch (Exception $e) { echo 'error 1'; } catch (Zend_Exception $e) { echo 'error 2'; } catch (Zend_Http_Client_Exception $e) { echo 'error 3'; } } return $returnValue; }

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  • Why "object reference not set to an instance of an object" doesn't tell us which object?

    - by Saeed Neamati
    We're launching a system, and we sometimes get the famous exception NullReferenceException with the message Object reference not set to an instance of an object. However, in a method where we have almost 20 objects, having a log which says an object is null, is really of no use at all. It's like telling you, when you are the security agent of a seminar, that a man among 100 attendees is a terrorist. That's really of no use to you at all. You should get more information, if you want to detect which man is the threatening man. Likewise, if we want to remove the bug, we do need to know which object is null. Now, something has obsessed my mind for several months, and that is: Why .NET doesn't give us the name, or at least the type of the object reference, which is null?. Can't it understand the type from reflection or any other source? Also, what are the best practices to understand which object is null? Should we always test nullability of objects in these contexts manually and log the result? Is there a better way?

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  • Gilda Garretón, a Java Developer and Parallelism Computing Researcher

    - by Yolande
    In a new interview titled “Gilda Garretón, a Java Developer and Parallelism Computing Research,” Garretón shares her first-hand experience developing with Java and Java 7 for very large-scale integration (VLSI) of computer-aided design (CAD). Garretón gives an insightful overview of how Java is contributing to the parallelism development and to the Electric VLSI Design Systems, an open source VLSI CAD application used as a research platform for new CAD algorithms as well as the research flow for hardware test chips.  Garretón considers that parallelism programming is hard and complex, yet important developments are taking place.  "With the addition of the concurrent package in Java SE 6 and the Fork/Join feature in Java SE 7, developers have a chance to rely more on existing frameworks and dedicate more time to the essence of their parallel algorithms." Read the full article here  

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  • What are the ways to start making actual/real-world programs using Java/C++ to excel my Programming Skills?

    - by Umer Hassan
    The programming that we learn at university is not that vast, like those are really small exercises to build our logic, but everyone knows that this will not be the scenario when I'll get out in the market as a professional programmer, I really want to make real life programs which would actual make some impacts and will be useful. Tell me in the light of your experience that how should I start making those programs and polish my self as a professional programmer, if there are any sources available for it then kindly also recommend me those.

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  • OpenGL: Attempt to allocate a texture to big for the current hardware

    - by AnonymousMan
    I'm getting the following error: java.io.IOException: Attempt to allocate a texture to big for the current hardware at org.newdawn.slick.opengl.InternalTextureLoader.getTexture(InternalTextureLoader.java:320) at org.newdawn.slick.opengl.InternalTextureLoader.getTexture(InternalTextureLoader.java:254) at org.newdawn.slick.opengl.InternalTextureLoader.getTexture(InternalTextureLoader.java:200) at org.newdawn.slick.opengl.TextureLoader.getTexture(TextureLoader.java:64) at org.newdawn.slick.opengl.TextureLoader.getTexture(TextureLoader.java:24) The image I'm trying to use is 128x128. System.out.println(GL11.glGetInteger(GL11.GL_MAX_TEXTURE_SIZE)); I get: 32. 32??!! My graphics card is AMD Radeon HD 7970M with 2048 MB GDDR5 RAM, I can run all the latest games in 1080p and 60fps with no problem, and those textures sure as hell doesn't look like they are 32x32 pixels to me! How can I fix this? -- Edit: Here's the chaos code I use to init OpenGL: Display.setDisplayMode(new DisplayMode(500,500)); Display.create(); if (!GLContext.getCapabilities().OpenGL11) { throw new Exception("OpenGL 1.1 not supported."); } Display.setTitle("Game"); glMatrixMode(GL_PROJECTION); glLoadIdentity(); GLU.gluPerspective(45, 1, 0.1f, 5000); Mouse.setGrabbed(true); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glEnable(GL_TEXTURE_2D); glClearColor(0, 0, 0, 0); glEnable(GL_DEPTH_TEST); glDepthFunc(GL_LEQUAL); glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); glEnable(GL_BLEND); glEnable(GL_POINT_SMOOTH); glEnable(GL_LINE_SMOOTH); glEnable(GL_POLYGON_SMOOTH); glEnable(GL_POLYGON_OFFSET_FILL); glShadeModel(GL_SMOOTH); Display is a LWJGL thing, it makes the OpenGL context and the window. Anyway, I don't think there's anything in the init code that can help me but you never know...

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  • What is the best way to go about testing that we handle failures appropriately?

    - by Earlz
    we're working on error handling in an application. We try to have fairly good automated test coverage. One big problem though is that we don't really know of a way to test some of our error handling. For instance, we need to test that whenever there is an uncaught exception, a message is sent to our server with exception information. The big problem with this is that we strive to never have an uncaught exception(and instead have descriptive error messages). So, how do we test something what we never want to actually happen?

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  • Java 7 Adoption at 79%

    - by Henrik Stahl
    According to a recent blog post from the cloud hosting company Jelastic, Java 7 adoption on their platform is now at 79%. While this is a single data point and should not be read too broadly, it does match other indicators we have that Java 7 is picking up, such as uptake among Oracle middleware customers, download statistics and online activity. The spike in adoption in April coincided with the release of JDK 7 Update 4. This is in line with our expectations since that release added Mac OS X support as well as java.com moving to Java 7 as the default download for end-users; two events that marked the maturity of Java 7 to the community. Since the original release of Java 7, Oracle has shipped 7 update releases, added ports to Mac OSX and Linux/ARM and expanded JavaFX to all common desktop platforms.

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  • Is Java viable for serious game development?

    - by tehtros
    Ever since I was a little kid, my dream has been to develop games. Well, now that I am older, more mature, and have some programming experience, I would like to start. However, I would like to turn this into a career. The problem, is that my language of choice is Java. Now, I am not intending this to be a Java vs. C++ question, but rather, is Java an acceptable language for serious game development, instead of lower level languages like C++. By serious, I mean high quality graphics, and being able to play a game with said high quality graphics, without much lag on decent computers. Also, eventually, possible making it to consoles. I have scoured the internet, but there are not very many resources for Java game development, not nearly as many as C++. In fact, most engines are written in C++. Once, I tried to play a made with jMonkeyEngine. The game was terribly slow, to the point where my computer froze. I had no other Java applications running and nothing too resource intensive. Keep in mind, that my computer can play most modern 3D games with ease. So, I am really serious about game development, is Java still a viable choice? I have tried multiple times to learn C++, but I don't really like the language. I don't really know why, but usually, whenever I try to learn, I can never grasp the topics. Also, my most of my friends know Java, and one is even anti-C++, saying that no one knows how to use it right. Then, he goes to say that "there is no right way to use C++, that it can not be used correctly. The nature of the language prevents good code." Also, if I continue to learn and improve Java now, and it turns out that later I am required to learn C++, will making the switch be difficult? So, in short, can Java be taken serious, for serious game development. This includes heavy graphics, fast game play without lag, and possibly, and easy switch to consoles?

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  • A good substitute for ASMX web service methods, but not a general handler

    - by Saeed Neamati
    The best thing I like about ASP.NET MVC, is that you can directly call a server method (called action), from the client. This is so convenient, and so straightforward, that I really like to implement such a model in ASP.NET WebForms too. However, in ASP.NET WebForms, to call a server method from the client, you should either use Page Methods, or Web Services, both of which use SOAP as their communication protocol (though JSON can also be used). There is also another substitution, which is using Generic Handlers. The problem with them however is that, a separate Generic Handler should be written for each server method. In other words, each Generic Handler works like a simple method. Is there anyway else to imitate MVC model in ASP.NET WebForms? Please note that I can't change to MVC platform right now, cause the project at our hand is a big project and we don't have required resources and time to change our platform. What we seek, is a simple MVC model implementation for our AJAX calls. A problem that we have with Web Services, is the known problem of SoapException, and we're not interested in creating custom SoapExctensions.

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  • Java regex patterns - compile time constants or instance members?

    - by KepaniHaole
    Currently, I have a couple of singleton objects where I'm doing matching on regular expressions, and my Patterns are defined like so: class Foobar { private final Pattern firstPattern = Pattern.compile("some regex"); private final Pattern secondPattern = Pattern.compile("some other regex"); // more Patterns, etc. private Foobar() {} public static Foobar create() { /* singleton stuff */ } } But I was told by someone the other day that this is bad style, and Patterns should always be defined at the class level, and look something like this instead: class Foobar { private static final Pattern FIRST_PATTERN = Pattern.compile("some regex"); private static final Pattern SECOND_PATTERN = Pattern.compile("some other regex"); // more Patterns, etc. private Foobar() {} public static Foobar create() { /* singleton stuff */ } } The lifetime of this particular object isn't that long, and my main reason for using the first approach is because it doesn't make sense to me to hold on to the Patterns once the object gets GC'd. Any suggestions / thoughts?

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