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  • Java: Local Enums

    - by bruno conde
    Today, I found myself coding something like this ... public class LocalEnums { public LocalEnums() { } public void foo() { enum LocalEnum { A,B,C }; // .... // class LocalClass { } } } and I was kind of surprised when the compiler reported an error on the local enum: The member enum LocalEnum cannot be local Why can't enums be declared local like classes? I found this very useful in certain situations. In the case I was working, the rest of the code didn't need to know anything about the enum. Is there any structural/design conflict that explains why this is not possible or could this be a future feature of Java?

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  • Concurency problem with Isolation - read-committed

    - by Ratn Deo--Dev
    I have to write a simple demo for amount withdrawl from a joint Bank amount .Andy and Jen holds a joint bank account with number 123 . Suppose they have 100$ in their account .Jen and Andy are operating their account at the same time and both are trying to withdraw 90$ at the time being .My transaction Isolation is set to read-committed and both are able to withdraw money leaving the balance to -(minus)80$ although I have constraint that balance should never be less than 0. I am using hibernate .Is versioning only way to solve this problem or I should go for another Isolation level ?

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  • How does 'binding' in JSF work?

    - by Roman
    I've created custom component which shows chart. Now I need to make binding support for this component i.e. generated chart-image should be available (as array of bytes) to backing bean via binding mechanism. I'd like to know some general info about binding implementation techniques. Any links and examples are welcome as well. Thanks in advance!

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  • How do I access Glassfish V3 Administration Console Website from a remote host

    - by Tom
    I have installed Glassfish v3 on a standalone server running ubuntu-server 9.10. I can open the Admin website if I use a browser running on the server by browsing to: http:// localhost:4848/ I would like to access it from a remote machine by browsing to something like http:// mydomain.com:4848/ The firewall is definitely allowing traffic through on that port (4848) and I can access the application server by browsing to: http:// mydomain.com:8080/ How can I allow remote access to the administration website?

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  • How to get image height and width using java?

    - by Dick Song
    Is there any other way beside using imageIO.read to get image height and width? Because I encounter some issue that will lockup the thread. at com.sun.medialib.codec.jpeg.Decoder.njpeg_decode(Native Method) at com.sun.medialib.codec.jpeg.Decoder.decode(Decoder.java:87) at com.sun.media.imageioimpl.plugins.jpeg.CLibJPEGImageReader.decode(CLibJPEGImageReader.java:73) - locked <0xd96fb668> (a com.sun.media.imageioimpl.plugins.jpeg.CLibJPEGImageReader) at com.sun.media.imageioimpl.plugins.clib.CLibImageReader.getImage(CLibImageReader.java:320) - locked <0xd96fb668> (a com.sun.media.imageioimpl.plugins.jpeg.CLibJPEGImageReader) at com.sun.media.imageioimpl.plugins.clib.CLibImageReader.read(CLibImageReader.java:384) - locked <0xd96fb668> (a com.sun.media.imageioimpl.plugins.jpeg.CLibJPEGImageReader) at javax.imageio.ImageIO.read(ImageIO.java:1400) at javax.imageio.ImageIO.read(ImageIO.java:1322) This error only occurs on sun app server I suspect that it is a sun bug

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  • Is there a DRMAA Java library that works with Torque/PBS?

    - by dondondon
    Does anybody know a Java implementation of the DRMAA-API that is known to work with PBS/Torque cluster software? The background behind this: I would like to submit jobs to a newly set-up linux cluster from java using a DRMAA compliant API. The cluster is managed by PBS/Torque. Torque includes PBS DRMAA 1.0 library for Torque/PBS that contains a DRMA-C binding and provides in libdrmaa.so and .a binaries. I know that Sun grid engine includes a drmaa.jar providing a Java-DRMAA API. In fact I opted to use SGE but it was decided to try PBS first. The theory behind that decision was: 'DRMAA is a standard and therefore a Java API needs only a standards compliant drmaa-c binding.' However, I couldn't find such 'general DRMAA-C-java API' and now assume that this assumption is wrong and that the Java libraries are engine specific. Are we stuck here? Any comments appreciated.

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  • Java2d: Set gradient for a lines

    - by Algorist
    Hi, I am having multiple points in a plane and some hundreds of lines pass through those points. Some points can have more lines passing through them than other points. I want to show some kind of more gradient or brightness associated with lines crowded together. Is this possible to do in java2d. Please refer to this : http://ft.ornl.gov/doku/_media/ft/projects/paraxis.jpg Thank you.

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  • Object Oriented Database - why most of the companies do not use them

    - by GigaPr
    Hi, I am pretty new to programming(just finished University). I have been thought in the last 4 years about Object Oriented development and the numerous advantages of this approach. My question is Isn't it easier to use a pure Object Oriented database in development applications? Why Object Oriented database are not as much diffuse as relational? From my point of view makes sense to use OO database, the latter will avoid the numerous construction necessary for the mapping of complex objects on the tables.

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  • biginteger calucation prfoblem

    - by murali
    hi i am using the following code but the parameters are not passed to the methods. BigInteger p = BigInteger.valueOf(0); BigInteger u1 = obj.bigi_calc(g1, l); in this g1,l are long values the method is private BigInteger bigi_calc(long g1, long l){ BigInteger cal = BigInteger.valueOf(g1); BigInteger cal1= BigInteger.valueOf(l); for(BigInteger f = BigInteger.ONE;f.compareTo(cal1)>0;f=f.add(BigInteger.ONE)){ //BigInteger p= BigInteger.valueOf(0); p = cal.multiply(cal1); System.out.println("check p"+p); } // System.out.println("check p"+p); return p; } the elipse shows that it may be out of sync.. but the paramerters are not passed to the functions.. can you plz help me to slove this problem

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  • Existing Maven Project on Amazon Beanstalk

    - by Abhishek Ranjan
    I am trying to migrate my existing Maven project to Amazon Beanstalk. Looking at amazon's documentation,i don't see any maven project deployment instructions. I tried to upload the war file generated but the application is not coming up on beanstalk. I would like to know if there is any existing documentation to deploy on beanstalk from maven. I have Spring Data JPA,Spring MVC application,do i need to do specific configuration or move configuration files from within the WAR file.

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  • Does JavaME and/or Proguard reorder assignments?

    - by chrisdew
    This is a simplified example - I have two threads: Can JavaME and/Proguard ever reorder the obX = ... statements, such that thread_B will have a null pointer exception at ob2.someMethod? thread_A: Object ob1 = null; Object ob2 = null; ... ob1 = something1; ob2 = something2; thread_B: if (ob2 != null) { ob1.someMethod(); ... } P.S. I do realise that synchronising these will avoid the issue. Synchronisation has both a performance overhead, and more importantly, a chance to introduce deadlock.

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  • Best practices for caching results of JSP pages?

    - by Spines
    My application has an MVC structure. How should I structure my application to allow for maximum caching? Is it sufficient to only cache the model objects that are passed to the JSP views? Or will there be a significant performance boost from caching the results of the rendering of the JSP views too?

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  • What's a good 2nd level cache for JEE applications?

    - by Hank
    Can anyone recommend a good 2nd level object caching solution for JEE 6 applications, and give background to your recommendation? I'm using JPA 2.0 as persistence provider. I am particularly worried about having to run the cache client as a single-thread / singleton bean. Is that the case? If so, is that an issue? I've good experience using memcached from a PHP webapp, but PHP is of course single-threaded, so that was never an issue...

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  • Generics and Performance question.

    - by Tarmon
    Hey Everyone, I was wondering if anyone could look over a class I wrote, I am receiving generic warnings in Eclipse and I am just wondering if it could be cleaned up at all. All of the warnings I received are surrounded in ** in my code below. The class takes a list of strings in the form of (hh:mm AM/PM) and converts them into HourMinute objects in order to find the first time in the list that comes after the current time. I am also curious about if there are more efficient ways to do this. This works fine but the student in me just wants to find out how I could do this better. public class FindTime { private String[] hourMinuteStringArray; public FindTime(String[] hourMinuteStringArray){ this.hourMinuteStringArray = hourMinuteStringArray; } public int findTime(){ HourMinuteList hourMinuteList = convertHMStringArrayToHMArray(hourMinuteStringArray); Calendar calendar = new GregorianCalendar(); int hour = calendar.get(Calendar.HOUR_OF_DAY); int minute = calendar.get(Calendar.MINUTE); HourMinute now = new HourMinute(hour,minute); int nearestTimeIndex = findNearestTimeIndex(hourMinuteList, now); return nearestTimeIndex; } private int findNearestTimeIndex(HourMinuteList hourMinuteList, HourMinute now){ HourMinute current; int position = 0; Iterator<HourMinute> iterator = **hourMinuteList.iterator()**; while(iterator.hasNext()){ current = (HourMinute) iterator.next(); if(now.compareTo(current) == -1){ return position; } position++; } return position; } private static HourMinuteList convertHMStringArrayToHMArray(String[] times){ FindTime s = new FindTime(new String[1]); HourMinuteList list = s.new HourMinuteList(); String[] splitTime = new String[3]; for(String time : times ){ String[] tempFirst = time.split(":"); String[] tempSecond = tempFirst[1].split(" "); splitTime[0] = tempFirst[0]; splitTime[1] = tempSecond[0]; splitTime[2] = tempSecond[1]; int hour = Integer.parseInt(splitTime[0]); int minute = Integer.parseInt(splitTime[1]); HourMinute hm; if(splitTime[2] == "AM"){ hm = s.new HourMinute(hour,minute); } else if((splitTime[2].equals("PM")) && (hour < 12)){ hm = s.new HourMinute(hour + 12,minute); } else{ hm = s.new HourMinute(hour,minute); } **list.add(hm);** } return list; } class **HourMinuteList** extends **ArrayList** implements RandomAccess{ } class HourMinute implements **Comparable** { int hour; int minute; public HourMinute(int hour, int minute) { setHour(hour); setMinute(minute); } int getMinute() { return this.minute; } String getMinuteString(){ if(this.minute < 10){ return "0" + this.minute; }else{ return "" + this.minute; } } int getHour() { return this.hour; } void setHour(int hour) { this.hour = hour; } void setMinute(int minute) { this.minute = minute; } @Override public int compareTo(Object aThat) { if (aThat instanceof HourMinute) { HourMinute that = (HourMinute) aThat; if (this.getHour() == that.getHour()) { if (this.getMinute() > that.getMinute()) { return 1; } else if (this.getMinute() < that.getMinute()) { return -1; } else { return 0; } } else if (this.getHour() > that.getHour()) { return 1; } else if (this.getHour() < that.getHour()) { return -1; } else { return 0; } } return 0; } } If you have any questions let me know. Thanks, Rob

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  • Is JavaEE really portable?

    - by Bozho
    I'm just implementing a JavaEE assignment I was given on an interview. I have some prior experience with EJB, but nothing related to JMS and MDBs. So here's what I find through the numerous examples: application servers bind their topics and queues to different JNDI names - for example topic/queue, jms the activationConfig property is required on JBoss, while in the Sun tutorial it is not. after starting my application, jboss warns me that my topic isn't bound (it isn't actually - I haven't bound it, but I expect it to be bound automatically - in fact, in an example for JBoss 4.0 automatic binding does seem to happen). A suggested solution is to map it in some jboss files or even use jboss-specific annotations. This might be just JBoss, but since it is certified to implement to spec, it appears the spec doesn't specify these these things. And there all the alleged portability vanishes. So I wonder - how come it is claimed that JavaEE is portable and you can take an ear and deploy it on another application server and it magically runs, if such extremely basic things don't appear to be portable at all. P.S. sorry for the rant, but I'm assume I might be doing/getting something wrong, so state your opinions.

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  • Making change recursively: How do I modify my algorithm to print all combinations?

    - by cb
    I have an algorithm that recursively makes change in the following manner: public static int makeChange(int amount, int currentCoin) { //if amount = zero, we are at the bottom of a successful recursion if (amount == 0){ //return 1 to add this successful solution return 1; //check to see if we went too far }else if(amount < 0){ //don't count this try if we went too far return 0; //if we have exhausted our list of coin values }else if(currentCoin < 0){ return 0; }else{ int firstWay = makeChange(amount, currentCoin-1); int secondWay = makeChange(amount - availableCoins[currentCoin], currentCoin); return firstWay + secondWay; } } However, I'd like to add the capability to store or print each combination as they successfully return. I'm having a bit of a hard time wrapping my head around how to do this. The original algorithm was pretty easy, but now I am frustrated. Any suggestions? CB

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  • Java2d: Translate the axes

    - by Algorist
    Hi, I am developing an application using Java2d. The weird thing I noticed is, the original is at the top left corner and x and y axis increases from there. Is there a way to move the origin bottom left? Thank you.

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  • Recommendations for an in memory database vs thread safe data structures

    - by yx
    TLDR: What are the pros/cons of using an in-memory database vs locks and concurrent data structures? I am currently working on an application that has many (possibly remote) displays that collect live data from multiple data sources and renders them on screen in real time. One of the other developers have suggested the use of an in memory database instead of doing it the standard way our other systems behaves, which is to use concurrent hashmaps, queues, arrays, and other objects to store the graphical objects and handling them safely with locks if necessary. His argument is that the DB will lessen the need to worry about concurrency since it will handle read/write locks automatically, and also the DB will offer an easier way to structure the data into as many tables as we need instead of having create hashmaps of hashmaps of lists, etc and keeping track of it all. I do not have much DB experience myself so I am asking fellow SO users what experiences they have had and what are the pros & cons of inserting the DB into the system?

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