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  • Long primitive or AtomicLong for a counter?

    - by Rich
    Hi I have a need for a counter of type long with the following requirements/facts: Incrementing the counter should take as little time as possible. The counter will only be written to by one thread. Reading from the counter will be done in another thread. The counter will be incremented regularly (as much as a few thousand times per second), but will only be read once every five seconds. Precise accuracy isn't essential, only a rough idea of the size of the counter is good enough. The counter is never cleared, decremented. Based upon these requirements, how would you choose to implement your counter? As a simple long, as a volatile long or using an AtomicLong? Why? At the moment I have a volatile long but was wondering whether another approach would be better. I am also incrementing my long by doing ++counter as opposed to counter++. Is this really any more efficient (as I have been led to believe elsewhere) because there is no assignment being done? Thanks in advance Rich

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  • Why is 1942/4/3 00:00:00 an illegal date in java.util.Calendar?

    - by Aleksi
    Is there something special in the date 3rd of April 1942? For some reason the the hour of day 0 (12:00 am) is illegal for this specific date. The date is accepted when a lenient calendar is used but the hour of day is incremented to 1 (1:00 am). Relevant code java.util.Calendar calendar = java.util.Calendar.getInstance(); calendar.clear(); calendar.setLenient(false); calendar.set(1942, 3, 3, 0, 0, 0); calendar.getTimeInMillis(); Exception java.lang.IllegalArgumentException: HOUR_OF_DAY at java.util.GregorianCalendar.computeTime(Unknown Source) at java.util.Calendar.updateTime(Unknown Source) at java.util.Calendar.getTimeInMillis(Unknown Source) I'd really prefer is the dates were not lenient as I don't want to accept impossible dates.

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  • Third Party Libraries and Technologies very Java Programmer must be aware of?

    - by kunjaan
    I agree that this is a very subjective question but as a student of Java , I get suggested good libraries and technologies for Java by my mentors at work. For example, I was not aware of Google Guice for Dependency Injection, awesomeness of Java Reflection APIs, ORMs like Hibernate or stuffs you could do with libraries like Hadoop. I want to collect and share some of the libraries that exemplifies good java programming (so that beginners like me could code walk and emulate the coding practice), teach unique concepts to Java (for example Dependency Injections or ORM) and/or are really interesting libraries that a student like me would get to do interesting projects on (eg. Hadoop). I redited this question 3 times to make it more specific : ). I am sorry if I am really not clear in my intentions. But some kind of a list of good concepts and third party libraries for Java could really help some of my intern friends here at work. Thank you.

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  • How do I make defensive copy of an object?

    - by kunjaan
    How do I make defensive copies of a Mutable Object which contains a mutable field in an Immutable Object? class ImmutableObject { private final MutableObject immutable_field; ImmutableObject(MutableObject y) { this.immutable_field = y; } MutableObject return_immutable_field() { return immutable_field; } } class MutableObject { public int mutable_field; } The MutableObject does not have a constructor that lets me set the field. The MutableObject's current state should be captured in the Immutable Object and never changed.

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  • Reference to an instance method of a particular object

    - by Andrey
    In the following code, if i try to pass method reference using the class name, works. But passing the reference variable compiler gives an error, i do not understand why? public class User { private String name; public User(String name) { this.name = name; } public void printName() { System.out.println(name); } } public class Main { public static void main(String[] args) { User u1 = new User("AAA"); User u2 = new User("BBB"); User u3 = new User("ZZZ"); List<User> userList = Arrays.asList(u1, u2, u3); userList.forEach(User::printName); // works userList.forEach(u1::printName); // compile error } } Thanks,

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  • Third Party Libraries and Technologies every Java Programmer must be aware of?

    - by kunjaan
    I agree that this is a very subjective question but as a student of Java , I get suggested good libraries and technologies for Java by my mentors at work. For example, I was not aware of Google Guice for Dependency Injection, awesomeness of Java Reflection APIs, ORMs like Hibernate or stuffs you could do with libraries like Hadoop. I want to collect and share some of the libraries that exemplifies good java programming (so that beginners like me could code walk and emulate the coding practice), teach unique concepts to Java (for example Dependency Injections or ORM) and/or are really interesting libraries that a student like me would get to do interesting projects on (eg. Hadoop). I redited this question 3 times to make it more specific : ). I am sorry if I am really not clear in my intentions. But some kind of a list of good concepts and third party libraries for Java could really help some of my intern friends here at work. Thank you.

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  • Upadate panel's child controls are not causing partial postback, the whole page gets reloaded with a

    - by Akshay
    I have put several buttons and panels in my update panel. I also have a script manager on that page. now when I click on any of the buttons then the functionality is working fine but problem is that the complete page gets reloaded witha a flick, instead of updating the update panel only. I have set the "children as trigger" property of update panel "true". please help.

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  • Why did you stop using Tapestry?

    - by ntownsend
    This question goes out to those who have used Tapestry as a web framework and then either gave it up or switched to something else, or even ported their application from Tapestry to something else. The question is why? What led you to make this change? EDIT: Also, what framework (if any) did you change to?

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  • Returning a href within a string

    - by user701254
    How can I return a href within a string, I can access the start position but not sure how to get last position : Here is what I have so far : String str = "sadf ad fas dfa http:\\www.google.com sdfa sadf as dfas"; int index = str.indexOf("http"); String href = str.substring(index , ???); What should the end index be ? Note, this is targeted at j2me & I need to minimise download footprint so I cannot use regular expressions or third party regular expressions libraries.

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  • Update panel in asp.net

    - by Senthilkumar
    Hi I am using two update panel..in nested way.. can i use like this and also in my project im using clientscript.RegisterScript along with update panel , its not giving any error but , my pop up is not being displayed when i click one item on grid. the pop up is in update panel which is inside (nested).. can anyone help ??? Thank you

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  • User control disapear when added to a Panel

    - by dutt
    I've got a user control class that works fine, drawing, events firing and the works. When i programmaticly add it to a class that extends from Panel it disapears. I've checked around and the line that makes it disapear is the line where i go panel.Controls.Add(myuserControl). Without that line the control works just fine, does anybody know why it won't show after the add? I'm currently doing the painting of the user control by overriding OnPaint, but the panel is using the default painting.

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  • Can't save my picture

    - by mamii
    I want to save the image that I draw, but I always failure is reported. I have tested and tried but I can correct any errors. Therefore, I appeal to you. This store is for me as a "cancer sore". And what is the drawing application without the possibility shranjevnja? sucks: D Question: What is wrong with my code for storage? or anything else? Posts: 09-12 07:30:34.346: E / Panel (8003): IOEception 09-12 07:30:34.346: E / Panel (8003): java.io.IOException: Parent directory of file does not exist: / sdcard/anppp/2012Sep1273034.png 09-12 07:30:34.346: E / Panel (8003): at java.io.File.createNewFile (File.java: 1263) 09-12 07:30:34.346: E / Panel (8003): at aa.bb.cc.Panel.saveapp (Panel.java: 67) 09-12 07:30:34.346: E / Panel (8003): at aa.bb.cc.AndroidPaint.onOptionsItemSelected (AndroidPaint.java: 94) 09-12 07:30:34.346: E / Panel (8003): at android.app.Activity.onMenuItemSelected (Activity.java: 2170) 09-12 07:30:34.346: E / Panel (8003): at com.android.internal.policy.impl.PhoneWindow.onMenuItemSelected (PhoneWindow.java: 730) 09-12 07:30:34.346: E / Panel (8003): at com.android.internal.view.menu.MenuItemImpl.invoke (MenuItemImpl.java: 139) 09-12 07:30:34.346: E / Panel (8003): at com.android.internal.view.menu.MenuBuilder.performItemAction (MenuBuilder.java: 855) 09-12 07:30:34.346: E / Panel (8003): at com.android.internal.view.menu.ExpandedMenuView.invokeItem (ExpandedMenuView.java: 89) 09-12 07:30:34.346: E / Panel (8003): at com.android.internal.view.menu.ExpandedMenuView.onItemClick (ExpandedMenuView.java: 93) 09-12 07:30:34.346: E / Panel (8003): at android.widget.AdapterView.performItemClick (AdapterView.java: 284) 09-12 07:30:34.346: E / Panel (8003): at android.widget.ListView.performItemClick (ListView.java: 3285) 09-12 07:30:34.346: E / Panel (8003): at android.widget.AbsListView $ PerformClick.run (AbsListView.java: 1640) 09-12 07:30:34.346: E / Panel (8003): at android.os.Handler.handleCallback (Handler.java: 587) 09-12 07:30:34.346: E / Panel (8003): at android.os.Handler.dispatchMessage (Handler.java: 92) 09-12 07:30:34.346: E / Panel (8003): at android.os.Looper.loop (Looper.java: 123) 09-12 07:30:34.346: E / Panel (8003): at android.app.ActivityThread.main (ActivityThread.java: 4363) 09-12 07:30:34.346: E / Panel (8003): at java.lang.reflect.Method.invokeNative (Native Method) 09-12 07:30:34.346: E / Panel (8003): at java.lang.reflect.Method.invoke (Method.java: 521) 09-12 07:30:34.346: E / Panel (8003): at com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run (ZygoteInit.java: 860) 09-12 07:30:34.346: E / Panel (8003): at com.android.internal.os.ZygoteInit.main (ZygoteInit.java: 618) 09-12 07:30:34.346: E / Panel (8003): at dalvik.system.NativeStart.main (Native Method) There is code: private Bitmap mBitmap; private Canvas mCanvas; private Bitmap tmpBitmap; private Canvas tmpCanvas; private DrawHandler mDrawHandler; private Canvas tCanvas; private String mImagePath = Environment.getExternalStorageDirectory() + "/anppp"; private File file; public void saveapp() { Calendar currentDate = Calendar.getInstance(); SimpleDateFormat formatter= new SimpleDateFormat("yyyyMMMddHmmss"); String dateNow = formatter.format(currentDate.getTime()); file = new File(mImagePath + "/" + dateNow +".png"); FileOutputStream fos; try { file.createNewFile(); fos = new FileOutputStream(file); tmpBitmap.compress(Bitmap.CompressFormat.PNG, 100, fos); fos.close(); } catch (FileNotFoundException e) { Log.e("Panel", "FileNotFoundException", e); } catch (IOException e) { Log.e("Panel", "IOEception", e); } } That's it .. I do not know what could be wrong ;(

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  • J2ME linking interfaces.

    - by user554031
    Hey guys, I've been working with J2ME for a short while, however I've been unable to find anything regarding my query. I'm wanting to link interfaces, I.E A to B to C. Similar to a card layout. Information on each interface changes based on the choices the user made previously. For example City - Cinema - Cinema Listings. The eventual target is to create a MIDlet that displays information from a database (I understand a midlet needs to connect to a servlet which connects to the DB). Thanks in advance for you're time.

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  • How do I run compiled java classes with GPU libraries (Jogamp JOCL)?

    - by jam383
    Does anyone know how to run the java code from the command line with dependency on GPU libraries in this case Jogamps JOCL. I have compiled a test program HelloJOCL.java but I get an error during run time. I tried javac -classpath "./lib/jocl.jar:./lib/jocl-natives-macosx-universal.jar:./lib/jocl-natives-linux-i586.jar:./lib/jocl-natives-linux-amd64.jar:./lib/gluegen-rt.jar:./lib/gluegen-rt-natives-linux-amd64.jar:./lib/gluegen-rt-natives-macosx-universal.jar:./lib/gluegen-rt-natives-linux-i586.jar" ./HelloJOCL.java java -classpath "./lib/jocl.jar:./lib/jocl-natives-macosx-universal.jar:./lib/jocl-natives-linux-i586.jar:./lib/jocl-natives-linux-amd64.jar:./lib/gluegen-rt.jar:./lib/gluegen-rt-natives-linux-amd64.jar:./lib/gluegen-rt-natives-macosx-universal.jar:./lib/gluegen-rt-natives-linux-i586.jar:." HelloJOCL but get this error Exception in thread "main" java.lang.NoClassDefFoundError: com/jogamp/opencl/CLContext at java.lang.Class.getDeclaredMethods0(Native Method)

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  • How to make Eclipse compile with Java 1.5 in Mac OS X Leopard (10.5)?

    - by whiskeyspider
    I have been developing in Snow Leopard (10.6). I believe I have some Java6-only API features and I'd like to find these. I moved my project to Leopard (10.5) -- since Snow Leopard does not support Java 1.5 -- but I am so far unable to make Eclipse give compile errors for a Java API call which I know to have been added in 1.6. Here is what I have done: Project properties - Java Compiler - set everything to 1.5. Preferences - Java - Installed JREs - selected JVM 1.5.0. Project properties - Java Build Path - Libraries - says JRE System Library [JVM 1.5.0] What am I missing? Is there another way to find Java API calls added in 1.6 when using Eclipse in Snow Leopard? Thanks.

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  • The Next Frontier: Java Embedded @ JavaOne

    - by Kristin Rose
    Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Now more than ever, the Java platform is the best technology for many embedded use cases. Java’s platform independence, high level of functionality, security, and developer productivity, address the key pain points in building embedded solutions... and that’s not just our opinion. Take a look at the new IDC report on Oracle’s stewardship of Java, “Java: Two and a half Years After the Acquisition” (doc #236309, August 2012). Java already powers around 3 billion devices worldwide, with traditional desktops and servers being only a small portion of that, and the ‘Internet of Things‘ is just really starting to explode. It is estimated that within five years, intelligent and connected embedded devices will outnumber desktops and mobile phones combined, and will generate the majority of the traffic on the Internet. Is your platform and services strategy ready for the coming disruptions and opportunities? It should come as no surprise that Oracle is enthusiastically focused on Java for Embedded .  New this year, Oracle is demonstrating its further commitment to the embedded marketplace by offering, for the first time, a dedicated conference focused on the business aspects of embedded Java: Java Embedded @ JavaOne. Co-located with the technically-focused JavaOne conference, Java Embedded @ JavaOne will run for two days in San Francisco targeting C-level executives, architects, business leaders, and decision makers. With 24 inspired business sessions with expert speakers from 18 prominent companies driving the next generation of Java Embedded business solutions (such as Cinterion, ARM, Hitachi and Rockwell Automation), attendees will learn how Java Embedded technologies and solutions can offer compelling value and a clear path forward to business efficiency and agility. You’ll also see how Oracle’s comprehensive technology portfolio can deliver a complete ‘Machine to Machine’ platform, from device to datacenter, resulting in a highly secure, resilient, high-performance and cost-effective solution. Seating is limited and we expect a lot of interest in this new event, so please register now! Note that if you are already attending the Oracle OpenWorld or JavaOne conferences, you can attend this conference for only $100 more. Watch my video below to find out more. I hope to see you there! Judson Althoff SVP of WWA&C Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

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  • Network cabling with multiple patch panels?

    - by dannymcc
    I am in the very early stages of planning a network cabling upgrade in our office, mainly to upgrade the old cables from Cat5 to either 5e or 6. I am also planning on upgrading all of our 10/100 switches to 10/100/1000 switches. I would like to have three small wall mounted cabinets spread around the building, each with a patch panel and switch. These would all lead back to our server room. The question is; should I have two patch panels in each wall cabinet, one with 24 or 48 ports that are connected to a matching patch panel in the server room. The second patch panel would then link to each device in that cabinets area. Then I wouldn't put a switch in the small cabinets. All switching would be done in the server room. Or, should I have one main cable from the server room to each of the cabinets - plugged straight into the switch and the patch panel is for devices in the cabinets area? I hope that makes sense!

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  • Generating Java classes out of XMLSchema.xsd using JAXB

    - by Christian Schulz
    I'm using jaxb to generate java classes out of a xml schema. The schema imports XMLSchema.xsd and its content is used as an element in the document. If I remove the import and the reference to "xsd:schema" respectively then the binding compiler generates successfully the classes. If I do not then it would produce the following errors, which are the same if I would try to generate Java classes from the XMLSchema.xsd only! C:\Users\me"%JAXB%/xjc" -extension -d tmp/uisocketdesc -p uis.jaxb uisocketdesc.xsd -b xml_binding_test.xml -b xml_binding_test_2.xml -b xml_binding_test_3.xml parsing a schema... compiling a schema... [ERROR] A class/interface with the same name "uis.jaxb.ComplexType" is already in use. Use a class customization to resolve this conflict. line 612 of "http://www.w3.org/2001/XMLSchema.xsd" [ERROR] (Relevant to above error) another "ComplexType" is generated from here. line 440 of "http://www.w3.org/2001/XMLSchema.xsd" [ERROR] A class/interface with the same name "uis.jaxb.Attribute" is already in use. Use a class customization to resolve this conflict. line 364 of "http://www.w3.org/2001/XMLSchema.xsd" [ERROR] (Relevant to above error) another "Attribute" is generated from here. line 1020 of "http://www.w3.org/2001/XMLSchema.xsd" [ERROR] A class/interface with the same name "uis.jaxb.SimpleType" is already in use. Use a class customization to resolve this conflict. line 2278 of "http://www.w3.org/2001/XMLSchema.xsd" [ERROR] (Relevant to above error) another "SimpleType" is generated from here. line 2222 of "http://www.w3.org/2001/XMLSchema.xsd" [ERROR] A class/interface with the same name "uis.jaxb.Group" is already in use. Use a class customization to resolve this conflict. line 930 of "http://www.w3.org/2001/XMLSchema.xsd" [ERROR] (Relevant to above error) another "Group" is generated from here. line 727 of "http://www.w3.org/2001/XMLSchema.xsd" [ERROR] A class/interface with the same name "uis.jaxb.AttributeGroup" is already in use. Use a class customization to resolve this conflict. line 1062 of "http://www.w3.org/2001/XMLSchema.xsd" [ERROR] (Relevant to above error) another "AttributeGroup" is generated from here. line 1026 of "http://www.w3.org/2001/XMLSchema.xsd" [ERROR] A class/interface with the same name "uis.jaxb.Element" is already in use. Use a class customization to resolve this conflict. line 721 of "http://www.w3.org/2001/XMLSchema.xsd" [ERROR] (Relevant to above error) another "Element" is generated from here. line 647 of "http://www.w3.org/2001/XMLSchema.xsd" [ERROR] Two declarations cause a collision in the ObjectFactory class. line 1020 of "http://www.w3.org/2001/XMLSchema.xsd" [ERROR] (Related to above error) This is the other declaration. line 364 of "http://www.w3.org/2001/XMLSchema.xsd" [ERROR] Two declarations cause a collision in the ObjectFactory class. line 2278 of "http://www.w3.org/2001/XMLSchema.xsd" [ERROR] (Related to above error) This is the other declaration. line 2222 of "http://www.w3.org/2001/XMLSchema.xsd" [ERROR] Two declarations cause a collision in the ObjectFactory class. line 930 of "http://www.w3.org/2001/XMLSchema.xsd" [ERROR] (Related to above error) This is the other declaration. line 727 of "http://www.w3.org/2001/XMLSchema.xsd" [ERROR] Two declarations cause a collision in the ObjectFactory class. line 440 of "http://www.w3.org/2001/XMLSchema.xsd" [ERROR] (Related to above error) This is the other declaration. line 612 of "http://www.w3.org/2001/XMLSchema.xsd" [ERROR] Two declarations cause a collision in the ObjectFactory class. line 1026 of "http://www.w3.org/2001/XMLSchema.xsd" [ERROR] (Related to above error) This is the other declaration. line 1062 of "http://www.w3.org/2001/XMLSchema.xsd" [ERROR] Two declarations cause a collision in the ObjectFactory class. line 647 of "http://www.w3.org/2001/XMLSchema.xsd" [ERROR] (Related to above error) This is the other declaration. line 721 of "http://www.w3.org/2001/XMLSchema.xsd" Failed to produce code.

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  • terminating java applet thread on page unload

    - by Hammad Tariq
    Hello, I have got a problem here in terminating the threads. The problem is that I am using applet thread to access JS DOM and manipulate innerHTML of a span to right the Thread Name as the innerHTML. It works fine until I keep refreshing the page but if I dont give it a sleep of like 200ms and go to another page which dont have any applet on it, it will give me an error in firebug console: document.getElementById("userName") is null What I am suspecting is, although I send an interrupt on stop and I have also tried the same by setting a flag variable of running in run while loop, the thread executes much faster than the time JVM takes to unload it and I get my page changed in browser but applet is still trying to find an element with id userName. Is that true? Is there any work around of it? Is there any way to know how many threads are running at the moment? Is there any kill all command to send on destroy()? I have searched a lot, seen all the API of java threads and applets, couldn't get this to work. Below is the code: import java.applet.Applet; import netscape.javascript.*; //No need to extend JApplet, since we don't add any components; //we just paint. public class firstApplet extends Applet { /** * */ private static final long serialVersionUID = 1L; firstThread first; boolean running = false; public class firstThread extends Thread{ JSObject win; JSObject doc; firstThread second; public firstThread(JSObject window){ this.win = window; } public void run() { try{ System.out.println("running... "); while (!isInterrupted()){ doc = (JSObject) win.getMember("document"); String userName = Thread.currentThread().getName(); //String userName = "John Doe"; String S = "document.getElementById(\"userName\").innerHTML = \""+userName+"\";"; doc.eval(S); Thread.sleep(5); } }catch(Exception e){ System.out.println("exception in first thread... "); e.printStackTrace(); } } } public void init() { System.out.println("initializing... "); } public void start() { System.out.println("starting... "); JSObject window = JSObject.getWindow(this); first = new firstThread(window); first.start(); running = true; } public void stop() { first.interrupt(); first = null; System.out.println("stopping... "); } public void destroy() { if(first != null){ first = null; } System.out.println("preparing for unloading..."); } } Thanks

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  • Real-time graphing in Java

    - by thodinc
    I have an application which updates a variable about between 5 to 50 times a second and I am looking for some way of drawing a continuous XY plot of this change in real-time. Though JFreeChart is not recommended for such a high update rate, many users still say that it works for them. I've tried using this demo and modified it to display a random variable, but it seems to use up 100% CPU usage all the time. Even if I ignore that, I do not want to be restricted to JFreeChart's ui class for constructing forms (though I'm not sure what its capabilities are exactly). Would it be possible to integrate it with Java's "forms" and drop-down menus? (as are available in VB) Otherwise, are there any alternatives I could look into? EDIT: I'm new to Swing, so I've put together a code just to test the functionality of JFreeChart with it (while avoiding the use of the ApplicationFrame class of JFree since I'm not sure how that will work with Swing's combo boxes and buttons). Right now, the graph is being updated immediately and CPU usage is high. Would it be possible to buffer the value with new Millisecond() and update it maybe twice a second? Also, can I add other components to the rest of the JFrame without disrupting JFreeChart? How would I do that? frame.getContentPane().add(new Button("Click")) seems to overwrite the graph. package graphtest; import java.util.Random; import javax.swing.JFrame; import org.jfree.chart.ChartFactory; import org.jfree.chart.ChartPanel; import org.jfree.chart.JFreeChart; import org.jfree.chart.axis.ValueAxis; import org.jfree.chart.plot.XYPlot; import org.jfree.data.time.Millisecond; import org.jfree.data.time.TimeSeries; import org.jfree.data.time.TimeSeriesCollection; public class Main { static TimeSeries ts = new TimeSeries("data", Millisecond.class); public static void main(String[] args) throws InterruptedException { gen myGen = new gen(); new Thread(myGen).start(); TimeSeriesCollection dataset = new TimeSeriesCollection(ts); JFreeChart chart = ChartFactory.createTimeSeriesChart( "GraphTest", "Time", "Value", dataset, true, true, false ); final XYPlot plot = chart.getXYPlot(); ValueAxis axis = plot.getDomainAxis(); axis.setAutoRange(true); axis.setFixedAutoRange(60000.0); JFrame frame = new JFrame("GraphTest"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); ChartPanel label = new ChartPanel(chart); frame.getContentPane().add(label); //Suppose I add combo boxes and buttons here later frame.pack(); frame.setVisible(true); } static class gen implements Runnable { private Random randGen = new Random(); public void run() { while(true) { int num = randGen.nextInt(1000); System.out.println(num); ts.addOrUpdate(new Millisecond(), num); try { Thread.sleep(20); } catch (InterruptedException ex) { System.out.println(ex); } } } } }

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  • using java Calendar

    - by owca
    I have a simple task. There are two classes : Ticket and Date. Ticket contains event, event place and event date which is a Date object. I also need to provide a move() method for Date object, so I used Calendar and Calendar's add(). Everything looks fine apart of the output. I constantly get 5,2,1 as the date's day,month,year. Lines with asterix return proper date. The code : Ticket class : public class Ticket { private String what; private String where; private Date when; public Ticket(String s1, String s2, Data d){ this.what = s1; this.where = s2; this.when = d; } *public Date giveDate(){ System.out.println("when in giveDate() "+this.when); return this.when; } public String toString(){ return "what: "+this.what+"\n"+"where: "+this.where+"\n"+"when: "+this.when; } } Date class: import java.util.Calendar; import java.util.GregorianCalendar; public class Date { public int day; public int month; public int year; public Date(int x, int y, int z){ *System.out.println("x: "+x); *System.out.println("y: "+y); *System.out.println("z: "+z); this.day = x; this.month = y; this.year = z; *System.out.println("this.day: "+this.day); *System.out.println("this.month: "+this.month); *System.out.println("this.year: "+this.year); } public Date move(int p){ *System.out.println("before_change: "+this.day+","+this.month+","+this.year); Calendar gc = new GregorianCalendar(this.year, this.month, this.day); System.out.println("before_adding: "+gc.DAY_OF_MONTH+","+gc.MONTH+","+gc.YEAR); gc.add(Calendar.DAY_OF_YEAR, p); System.out.println("after_adding: "+gc.DAY_OF_MONTH+","+gc.MONTH+","+gc.YEAR); this.year = gc.YEAR; this.day = gc.DAY_OF_MONTH; this.month = gc.MONTH; return this; } @Override public String toString(){ return this.day+","+this.month+","+this.year; } } Main for testing : public class Main { public static void main(String[] args) { Date date1=new Date(30,4,2002); Ticket event1=new Ticket("Peter Gabriel's gig", "London",date1 ); Ticket event2=new Ticket("Diana Kroll's concert", "Glasgow",date1 ); Date date2=event2.giveDate(); date2.move(30); Ticket event3=new Ticket("X's B-day", "some place",date2 ); System.out.println(date1); System.out.println(event1); System.out.println(event2); System.out.println(event3); } } And here's my output. I just can't get it where 5,2,1 come from :/ x: 30 y: 4 z: 2002 this.day: 30 this.month: 4 this.year: 2002 when in giveDate() 6,12,2004 before_change: 6,12,2004 before_adding: 5,2,1 after_adding: 5,2,1 5,2,1 what: Peter Gabriel's gig where: London when: 5,2,1 (...)

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  • Android: Use XML Layout for List Cell rather than Java Code Layout (Widgets)

    - by Stephen Finucane
    Hi, I'm in the process of making a music app and I'm currently working on the library functionality. I'm having some problems, however, in working with a list view (In particular, the cells). I'm trying to move from a simple textview layout in each cell that's created within java to one that uses an XML file for layout (Hence keeping the Java file mostly semantic) This is my original code for the cell layout: public View getView(int position, View convertView, ViewGroup parent) { String id = null; TextView tv = new TextView(mContext.getApplicationContext()); if (convertView == null) { music_column_index = musiccursor.getColumnIndexOrThrow(MediaStore.Audio.Media.TITLE); musiccursor.moveToPosition(position); id = musiccursor.getString(music_column_index); music_column_index = musiccursor.getColumnIndexOrThrow(MediaStore.Audio.Media.DISPLAY_NAME); musiccursor.moveToPosition(position); id += "\n" + musiccursor.getString(music_column_index); music_column_index = musiccursor.getColumnIndexOrThrow(MediaStore.Audio.Albums.ALBUM); musiccursor.moveToPosition(position); id += "\n" + musiccursor.getString(music_column_index); tv.setText(id); } else tv = (TextView) convertView; return tv; } And my new version: public View getView(int position, View convertView, ViewGroup parent) { View cellLayout = findViewById(R.id.albums_list_cell); ImageView album_art = (ImageView) findViewById(R.id.album_cover); TextView album_title = (TextView) findViewById(R.id.album_title); TextView artist_title = (TextView) findViewById(R.id.artist_title); if (convertView == null) { music_column_index = musiccursor.getColumnIndexOrThrow(MediaStore.Audio.Albums.ALBUM); musiccursor.moveToPosition(position); album_title.setText(musiccursor.getString(music_column_index)); //music_column_index = musiccursor.getColumnIndexOrThrow(MediaStore.Audio.Media.DISPLAY_NAME); //musiccursor.moveToPosition(position); music_column_index = musiccursor.getColumnIndexOrThrow(MediaStore.Audio.Media.TITLE); musiccursor.moveToPosition(position); artist_title.setText(musiccursor.getString(music_column_index)); } else{ cellLayout = (TextView) convertView; } return cellLayout; } The initialisation (done in the on create file): musiclist = (ListView) findViewById(R.id.PhoneMusicList); musiclist.setAdapter(new MusicAdapter(this)); musiclist.setOnItemClickListener(musicgridlistener); And the respective XML files: (main) <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent"> <ListView android:id="@+id/PhoneMusicList" android:layout_width="fill_parent" android:layout_height="fill_parent" /> <TextView android:id="@android:id/empty" android:layout_width="wrap_content" android:layout_height="0dip" android:layout_weight="1.0" android:text="@string/no_list_data" /> </LinearLayout> (albums_list_cell) <?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/albums_list_cell" android:layout_width="wrap_content" android:layout_height="wrap_content"> <ImageView android:id="@+id/album_cover" android:layout_alignParentLeft="true" android:layout_alignParentTop="true" android:layout_width="50dip" android:layout_height="50dip" /> <TextView android:id="@+id/album_title" android:layout_toRightOf="@+id/album_cover" android:layout_alignParentTop="true" android:layout_width="wrap_content" android:layout_height="wrap_content" /> <TextView android:id="@+id/artist_title" android:layout_toRightOf="@+id/album_cover" android:layout_below="@+id/album_title" android:layout_width="wrap_content" android:layout_height="15dip" /> </RelativeLayout> In theory (based on the tiny bit of Android I've done so far) this should work..it doesn't though. Logcat gives me a null pointer exception at line 96 of the faulty code, which is the album_title.setText line. It could be a problem with my casting but Google tells me this is ok :D Thanks for any help and let me know if you need more info!

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  • Java Synchronized List Deadlock

    - by portoalet
    From Effective Java 2nd edition item 67 page 266-268: The background thread calls s.removeObserver, which attempts to lock observers, but it can’t acquire the lock, because the main thread already has the lock. All the while, the main thread is waiting for the background thread to finish removing the observer, which explains the deadlock. I am trying to find out which threads deadlock in the main method by using ThreadMXBean (http://stackoverflow.com/questions/1102359/programmatic-deadlock-detection-in-java) , but why does it not return the deadlocked threads? I used a new Thread to run the ThreadMXBean detection. public class ObservableSet<E> extends ForwardingSet<E> { public ObservableSet(Set<E> set) { super(set); } private final List<SetObserver<E>> observers = new ArrayList<SetObserver<E>>(); public void addObserver(SetObserver<E> observer) { synchronized(observers) { observers.add(observer); } } public boolean removeObserver(SetObserver<E> observer) { synchronized(observers) { return observers.remove(observer); } } private void notifyElementAdded(E element) { synchronized(observers) { for (SetObserver<E> observer : observers) observer.added(this, element); } } @Override public boolean add(E element) { boolean added = super.add(element); if (added) notifyElementAdded(element); return added; } @Override public boolean addAll(Collection<? extends E> c) { boolean result = false; for (E element : c) result|=add(element); //callsnotifyElementAdded return result; } public static void main(String[] args) { ObservableSet<Integer> set = new ObservableSet<Integer>(new HashSet<Integer>()); final ThreadMXBean threadMxBean = ManagementFactory.getThreadMXBean(); Thread t = new Thread(new Runnable() { @Override public void run() { while( true ) { long [] threadIds = threadMxBean.findDeadlockedThreads(); if( threadIds != null) { ThreadInfo[] infos = threadMxBean.getThreadInfo(threadIds); for( ThreadInfo threadInfo : infos) { StackTraceElement[] stacks = threadInfo.getStackTrace(); for( StackTraceElement stack : stacks ) { System.out.println(stack.toString()); } } } try { System.out.println("Sleeping.."); TimeUnit.MILLISECONDS.sleep(1000); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } }); t.start(); set.addObserver(new SetObserver<Integer>() { public void added(ObservableSet<Integer> s, Integer e) { ExecutorService executor = Executors.newSingleThreadExecutor(); final SetObserver<Integer> observer = this; try { executor.submit(new Runnable() { public void run() { s.removeObserver(observer); } }).get(); } catch (ExecutionException ex) { throw new AssertionError(ex.getCause()); } catch (InterruptedException ex) { throw new AssertionError(ex.getCause()); } finally { executor.shutdown(); } } }); for (int i = 0; i < 100; i++) set.add(i); } } public interface SetObserver<E> { // Invoked when an element is added to the observable set void added(ObservableSet<E> set, E element); } // ForwardingSet<E> simply wraps another Set and forwards all operations to it.

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