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  • alternatyve in php (from java)

    - by Valdas
    I have some problem have class in java. But now need have in php. it's possible rewrite? Code: public class RealityStream { public RealityStream(byte abyte0[]) { m_dstream = null; m_dstream = new DataInputStream(new ByteArrayInputStream(abyte0)); } public int available() throws IOException { return m_dstream.available(); } public float readFloat() throws IOException { byte byte0 = m_dstream.readByte(); byte byte1 = m_dstream.readByte(); byte byte2 = m_dstream.readByte(); byte byte3 = m_dstream.readByte(); int i = (byte3 & 0xff) << 24 | (byte2 & 0xff) << 16 | (byte1 & 0xff) << 8 | byte0 & 0xff; return Float.intBitsToFloat(i); } public int readInt() throws IOException { byte byte0 = m_dstream.readByte(); byte byte1 = m_dstream.readByte(); byte byte2 = m_dstream.readByte(); byte byte3 = m_dstream.readByte(); return (byte3 & 0xff) << 24 | (byte2 & 0xff) << 16 | (byte1 & 0xff) << 8 | byte0 & 0xff; } public int readShort() throws IOException { byte byte0 = m_dstream.readByte(); byte byte1 = m_dstream.readByte(); return byte1 << 8 | byte0 & 0xff; } public int readUnsignedChar() throws IOException { return m_dstream.readUnsignedByte(); } private DataInputStream m_dstream; } very need. very thaks.

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  • Java: design for using many executors services and only few threads

    - by Guillaume
    I need to run in parallel multiple threads to perform some tests. My 'test engine' will have n tests to perform, each one doing k sub-tests. Each test result is stored for a later usage. So I have n*k processes that can be ran concurrently. I'm trying to figure how to use the java concurrent tools efficiently. Right now I have an executor service at test level and n executor service at sub test level. I create my list of Callables for the test level. Each test callable will then create another list of callables for the subtest level. When invoked a test callable will subsequently invoke all subtest callables test 1 subtest a1 subtest ...1 subtest k1 test n subtest a2 subtest ...2 subtest k2 call sequence: test manager create test 1 callable test1 callable create subtest a1 to k1 testn callable create subtest an to kn test manager invoke all test callables test1 callable invoke all subtest a1 to k1 testn callable invoke all subtest an to kn This is working fine, but I have a lot of new treads that are created. I can not share executor service since I need to call 'shutdown' on the executors. My idea to fix this problem is to provide the same fixed size thread pool to each executor service. Do you think it is a good design ? Do I miss something more appropriate/simple for doing this ?

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  • Why is this Java Calendar comparison bad?

    - by joe7pak
    Hello folks. I'm having an inexplicable problem with the Java Calendar class when I'm trying to compare to dates. I'm trying to compare to Calendars and determine if their difference is than 1 day, and do things bases on that difference or not. But it doesn't work. If I do this with the two dates: String currDate = aCurrentUTCCalendar.getTime().toString(); String localDate = aLocalCalendar.getTime().toString(); I get these results: currDate = "Thu Jan 06 05:58:00 MST 2010" localDate = "Tue Jan 05 00:02:00 MST 2010" This is correct. But if I do this: long curr = aCurrentUTCCalendar.getTime().getTime(); long local = aLocalCalendar.getTime().getTime(); I get these results: ( in milliseconds since the epoch ) curr = -125566110120000 local = 1262674920000 Since there is only about a 30 hour different between the two, the magnitudes are vastly different, not to mention that annoying negative sign. This causes problems if I do this: long day = 60 * 60 * 24 * 1000; // 86400000 millis, one day if( local - curr > day ) { // do something } What's wrong? Why are the getTime().toString() calls correct, but the getTime().getTime() calls are vastly different? I'm using jdk 1.6_06 on WinXP. I can't upgrade the JDK for various reasons.

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  • Is it possible to have an enum field in a class persisted with OrmLite?

    - by htf
    Hello. I'm trying to persist the following class with OrmLite: public class Field { @DatabaseField(id = true) public String name; @DatabaseField(canBeNull = false) public FieldType type; public Field() { } } The FieldType is a public enum. The field, corresponding to the type is string in SQLite (is doesn't support enums). When I try to use it, I get the following exception: INFO [main] (SingleConnectionDataSource.java:244) - Established shared JDBC Connection: org.sqlite.Conn@5224ee Exception in thread "main" org.springframework.beans.factory.BeanInitializationException: Initialization of DAO failed; nested exception is java.lang.IllegalArgumentException: Unknown field class class enums.FieldType for field FieldType:name=type,class=class orm.Field at org.springframework.dao.support.DaoSupport.afterPropertiesSet(DaoSupport.java:51) at orm.FieldDAO.getInstance(FieldDAO.java:17) at orm.Field.fromString(Field.java:23) at orm.Field.main(Field.java:38) Caused by: java.lang.IllegalArgumentException: Unknown field class class enums.FieldType for field FieldType:name=type,class=class orm.Field at com.j256.ormlite.field.FieldType.<init>(FieldType.java:54) at com.j256.ormlite.field.FieldType.createFieldType(FieldType.java:381) at com.j256.ormlite.table.DatabaseTableConfig.fromClass(DatabaseTableConfig.java:82) at com.j256.ormlite.dao.BaseJdbcDao.initDao(BaseJdbcDao.java:116) at org.springframework.dao.support.DaoSupport.afterPropertiesSet(DaoSupport.java:48) ... 3 more So how do I tell OrmLite, values on the Java side are from an enum?

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  • Java "Pool" of longs or Oracle sequence with reusable values

    - by Anthony Accioly
    Several months ago I implemented a solution to choose unique values from a range between 1 and 65535 (16 bits). This range is used to generate unique Route Targets suffixes, which for this customer massive network (it's a huge ISP) are a very disputed resource, so any free index needs to become immediately available to the end user. To tackle this requirement I used a BitSet. Allocate on the RT index with set and deallocate a suffix with clear. The method nextClearBit() can find the next available index. I handle synchronization / concurrency issues manually. This works pretty well for a small range... The entire index is small (around 10k), it is blazing fast and can be easy serialized into a Blob field. The problem is, some new devices can handle RTs of 32 bits (range 1 / 4294967296). Which can't be managed with a BitSet (it would, by itself, consume around 600Mb, plus be limited to int range). Even with this massive range available, the client still wants to free available Route Targets for the end user, mainly because the lowest ones (up to 65535) - which are compatible with old routers - are being heavily disputed. Before I tell the customer that this is impossible and he will have to conform with my reusable index for lower RTs (up to 65550) and use a database sequence for the other ones (which means that when the user frees a Route Target, it will not become available again). Would anyone shed some light? Maybe some kind soul already implemented a high performance number pool for Java (6 if it matters), or I am missing a killer feature of Oracle database (11R2 if it matters)... Wishful thinking. Thank you very much in advance.

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  • What is the most simple way to execute java class every 30 seconds

    - by Gandalf StormCrow
    I've been reading about java/spring/hibernate and worked trough a "dummy" examples so I told my friend to recommend something a bit harder for me, and now I'm stuck.. here is the simplest class I could think of package spring.com.practice; public class Pitcher { private String shout; public String getShout() { return shout; } public void setShout(String shout) { this.shout = shout; } public void voice() { System.out.println(getShout()); } } What is the most simple way to print out something by calling metod voice() from spring beans, and do it repeadatly every 30 seconds lets say, here is what I've got so far : <bean id="simpleTrigger" class="org.springframework.scheduling.quartz.SimpleTriggerBean"> <property name="jobDetail" ref="jobSchedulerDetail" /> <property name="startDelay" value="0" /> <property name="repeatInterval" value="30" /> </bean> <bean class="org.springframework.scheduling.quartz.SchedulerFactoryBean"> <property name="schedulerName" value="pitcherScheduler" /> <property name="triggers"> <list> <ref bean="simpleTrigger" /> </list> </property> </bean> <bean id="pitcher" class="spring.com.practice.Pitcher"> <property name="shout" value="I started executing..."></property> </bean> And yes I'm trying to run this on Jboss 5, I'm building a project with maven.

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  • transmit a java.lang.reflect.Proxy over a network

    - by panzi
    Is there a convenient way to transmit an object including its code (the class) over a network (not just the instance data)? Don't ask me why I want to do this. It's in an assignment. I asked several times if that is really what they meant and the didn't rephrase their answer so I guess they really want us to transmit code (not just the field data) over a network. To be honest I have no clue why we need a Proxy in this assignment anyway, just writing a simple class would do IMO. The assignment says that we should instantiate the proxy on the server and transmit it to the client (and yes, they talk about a java.lang.reflect.Proxy, they name this class). Because there is no class file for a proxy I can't deploy that. I guess I would have to somehow read out the bytecode of the generated Proxy, transmit it to the client and then load it. Which makes absolutely no sense at all, but this seems what they want us to do. I don't get why.

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  • How to implement Administrator rights in Java Application?

    - by Yatendra Goel
    I am developing a Data Modeling Software that is implemented in Java. This application converts the textual data (stored in a database) to graphical form so that users can interpret the data in a more efficient form. Now, this application will be accessed by 3 kinds of persons: 1. Managers (who can fill the database with data and they can also view the visual form of the data after entering the data into the database) 2. Viewers (who can only view the visual form of data that has been filled by managers) 3. Administrators (who can create and manage other administrators, managers and viewers) Now, how to implement 3 diff. views of the same application. Note: Managers, Viewers and Administrators can be located in any part of the world and should access the application through internet. One idea that came in my mind is as follows: Step1: Code all the business logic in EJBs so that it can be used in distributed environment (means which can be accessed by several users through internet) Step2: Code 3 Swing GUI Clients: One for administrators, one for managers and one for viewers. These 3 GUI clients can access business logic written in EJBs. Step3: Distribute the clients corresponding to their users. For instance, manager client to managers. =================================QUESTIONS======================================= Q1. Is the above approach is correct? Q2. This is very common functionality that various softwares have. So, Do they implement this kind of functionality through this way or any other way? Q3. If any other approach would be more better, then what is that approach?

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  • regexp in java problem

    - by Staszek28
    Hello! I found some problem while testing my NLP system. I have a java regex "(.\.\s)*Dendryt.*" and for string "v Table of Contents List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . " it just dont stop computing. Its clear that this regex complexity is very high, I will try to refactor it. Have you some suggestions for me for a future regex development ??? Thanks.

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  • Most awkward/misleading method in Java Base API ?

    - by JG
    I was recently trying to convert a string literal into a boolean, when the method "boolean Boolean.getBoolean(String name)" popped out of the auto-complete window. There was also another method ("boolean Boolean.parseBoolean(String s)") appearing right after, which lead me to search to find out what were the differences between these two, as they both seemed to do the same. It turns out that what Boolean.getBoolean(String name) really does is to check if there exists a System property (!) of the given name and if its value is true. I think this is very misleading, as I'm definitely not expecting that a method of Boolean is actually making a call to System.getProperty, and just by looking at the method signature, it sure looks (at least to me) like it should be used to parse a String as a boolean. Sure, the javadoc states it clearly, but I still think the method has a misleading name and is not in the right place. Other primitive type wrappers, such as Integer also have a similar method. Also, it doesn't seem to be a very useful method to belong in the base API, as I think it's not very common to have something like -Darg=true. Maybe it's a good question for a Java position interview: "What is the output of Boolean.getBoolean("true")?". I believe a more appropriate place for those methods would be in the System class, e.g., getPropertyAsBoolean; but again, I still think it's unnecessary to have these methods in the base API. It'd make sense to have these in something like the Properties class, where it's very common to do this kind of type conversions. What do you think of all this ? Also, if there's another "awkward" method that you're aware of, please post it. N.B. I know I can use Boolean.valueOf or Boolean.parseBoolean to convert a string literal into a boolean, but I'm just looking to discuss the API design.

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  • Java Enumeration of Musical Notes

    - by Crupler
    How would you create an enumeration of the musical notes in Java, with each notes having an octave and then a keyed variable? This is what I have so far... public enum Notes { c, cS, d, dS, e, f, fS, g, gS, a, aS, b; int octave; boolean isPlaying; } So when I access the enums in my code I write something like this... Notes.c.octave = 4; Notes.c.isPlaying = true; Now here is my question: How can I have an isPlaying boolean for each note in each octave? Like so: Notes.c.octave.isPlaying = true; Or would I have to go like: public enum Notes { c1, cS1, d1, dS1, e1, f1, fS1, g1, gS1, a1, aS1, b1 c2, cS2, d2, dS2, e2, f2, fS2, g2, gS2, a2, aS2, b2; etc... boolean isPlaying; } Thank you in advance for taking your time to answer this question!

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  • Tab Bar and Nav Controller: Where did I go wrong in my Interface Builder wiring?

    - by editor
    Even if you don't know how I've shot myself in the foot, a story which I've tried to lay out below, if you think I've done a good job showing the parameters of my problem I'd appreciate an upvote so that I might be able to grab some attention for my question. I've been working on an iPhone application in XCode and Interface Builder of the Tab Bar project type. After getting a table view of topics (business sectors) working fine I realized that I would need to add a Navigation Control to allow the user to drill into a subtopics (subsectors) table. As a green Objective-C developer, that was confusing, but I managed to get it working by reading various documentation trying out a few different IB options. My current setup is a Tab Bar Controller with Tab 1 as a Navigation Controller and Tab 2 a plain view with a Table View placed into it. The wiring works: I can log when table rows are selected and I'm ready to push a new View Controller onto the stack so that I can display the subtopics Table View. My problem: For some reason the first tab's Table View is a delegate and dataSource of the second ta. It doesn't make sense to me and I can't figure out why that's the only setup that works. Here is the wiring: Navigation Controller (Sectors) is a delegate of Tab Bar Navigation Bar is a delegate of Navigation Controller (Sectors) View Contoller (Sectors) has a view of Table View Table View (in Navigation Controller (Sectors)) is a delegate of First View Controller (Companies) Table View (in Navigation Controller (Sectors)) is a dataSource outlet of First View Controller (Companies) First View Controller (Companies) First View Contoller (Sectors) has a view of Table View Table View (in First View Controller (Companies)) is not hooked up to a dataSource outlet and is not a delegate When I click the tab buttons and look at the Inspector I see that the first tab is correctly hooked up to my MainWindow.xib and the second tab has selected a nib called SecondView.xib. It's in the File's Owner of MainWindow.xib where I inherit UITableViewDataSource and UITableViewDelegate (and also UITabBarControllerDelegate) in the .h, and in the .m where I implement the delegate methods. Why does this setup only work when the Table View in my first tab (View Controller (Sectors)) is a delegate and dataSource of the second tab? I'm confused: why wouldn't it need to be hooked up to the Navigation Controller-enabled tab in which the Table View is seen (Navigation Controller (Sectors))? The Table View seen on the second tab has neither dataSource and is not a delegate. I'm having trouble getting a pushViewController to fire (self.navigationController is not nil but the new View Controller still doesn't load) and I suspect that I need to work out this IB wiring issue before I can troubleshoot why the Nav Controller won't push a new View Controller onto the stack. if(nil == self.navigationController) { NSLog(@"self.navigationController is nil."); } else { NSLog(@"self.navigationController is not nil."); SectorList *subsectorViewController = [[SectorList alloc] initWithNibName:@"SectorList" bundle:nil]; subsectorViewController.title = @"Subsectors"; [[self navigationController] pushViewController:subsectorViewController animated:YES]; [subsectorViewController release]; }

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  • Create cross platform Java SWT Application

    - by mchr
    I have written a Java GUI using SWT. I package the application using an ANT script (fragment below). <jar destfile="./build/jars/swtgui.jar" filesetmanifest="mergewithoutmain"> <manifest> <attribute name="Main-Class" value="org.swtgui.MainGui" /> <attribute name="Class-Path" value="." /> </manifest> <fileset dir="./build/classes" includes="**/*.class" /> <zipfileset excludes="META-INF/*.SF" src="lib/org.eclipse.swt.win32.win32.x86_3.5.2.v3557f.jar" /> </jar> This produces a single jar which on Windows I can just double click to run my GUI. The downside is that I have had to explicitly package the windows SWT package into my jar. I would like to be able to run my application on other platforms (primarily Linux and OS X). The simplest way to do it would be to create platform specific jars which packaged the appropriate SWT files into separate JARs. Is there a better way to do this? Is it possible to create a single JAR which would run on multiple platforms?

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  • Sync version of the project with Java

    - by Alexadar
    I have a problem, I need to sync version of the project. Changes are performed on main project that resides on central Coldfusion server. There are about 30 remote Coldfusion servers, that has to sync with latest version on central server. New synch application will to be done in Java! I have a direct link to each remote location. Mostly Windows OS and Windows tools are used. My idea: The synchronization is performed at the level of synchronization of folders. I would like to avoid the use of SVN and similar tools. My idea is to carry out comparison of folders on the local server (comparison is performed between the old and new versions),with NO communication with remote servers, make the difference between the versions and the same is sent to the remote machines. We will install Tomcat on every remote server. "Sync application" deployed on Tomcat will take care about differences. Remote server will return me an answer, about the success of the sync. Any kind of suggestion or completely new approach on this topic is more than welcome. Thanks Best regards

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  • slowAES encryption and java descryption

    - by amnon
    Hi , I've tried to implement the same steps as discussed in AES .NET but with no success , i can't seem to get java and slowAes to play toghter ... attached is my code i'm sorry i can't add more this is my first time trying to deal with encryption would appreciate any help private static final String ALGORITHM = "AES"; private static final byte[] keyValue = getKeyBytes("12345678901234567890123456789012"); private static final byte[] INIT_VECTOR = new byte[16]; private static IvParameterSpec ivSpec = new IvParameterSpec(INIT_VECTOR); public static void main(String[] args) throws Exception { String encoded = encrypt("watson?"); System.out.println(encoded); } private static Key generateKey() throws Exception { Key key = new SecretKeySpec(keyValue, ALGORITHM); // SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(ALGORITHM); // key = keyFactory.generateSecret(new DESKeySpec(keyValue)); return key; } private static byte[] getKeyBytes(String key) { byte[] hash = DigestUtils.sha(key); byte[] saltedHash = new byte[16]; System.arraycopy(hash, 0, saltedHash, 0, 16); return saltedHash; } public static String encrypt(String valueToEnc) throws Exception { Key key = generateKey(); Cipher c = Cipher.getInstance("AES/CBC/PKCS5Padding"); c.init(Cipher.ENCRYPT_MODE, key,ivSpec); byte[] encValue = c.doFinal(valueToEnc.getBytes()); String encryptedValue = new BASE64Encoder().encode(encValue); return encryptedValue; } public static String decrypt(String encryptedValue) throws Exception { Key key = generateKey(); Cipher c = Cipher.getInstance(ALGORITHM); c.init(Cipher.DECRYPT_MODE, key); byte[] decordedValue = new BASE64Decoder().decodeBuffer(encryptedValue); byte[] decValue = c.doFinal(decordedValue); String decryptedValue = new String(decValue); return decryptedValue; } the bytes returned are different thanks in advance .

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  • How to round a number to n decimal places in Java

    - by Alex Spurling
    What I'd like is a method to convert a double to a string which rounds using the half-up method. I.e. if the decimal to be rounded is a 5, it always rounds up the previous number. This is the standard method of rounding most people expect in most situations. I also would like only significant digits to be displayed. That is there should not be any trailing zeroes. I know one method of doing this is to use the String.format method: String.format("%.5g%n", 0.912385); returns: 0.91239 which is great, however it always displays numbers with 5 decimal places even if they are not significant: String.format("%.5g%n", 0.912300); returns: 0.91230 Another method is to use the DecimalFormatter: DecimalFormat df = new DecimalFormat("#.#####"); df.format(0.912385); returns: 0.91238 However as you can see this uses half-even rounding. That is it will round down if the previous digit is even. What I'd like is this: 0.912385 -> 0.91239 0.912300 -> 0.9123 What is the best way to achieve this in Java?

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  • implementing a Intelligent File Transfer Software in java over TCP/IP

    - by whyjava
    Hello I am working on a proposal where we have to implement a software which can move files between one source to destination.The overall goal of this project is to create intelligent file transfer.This software will have three components :- 1) Broker : Broker is the module that communicates with other brokers, monitors files, moves files, retrieves configurations from the Configuration Manager, supplies process information for the monitor, archives files, writes all process data to log files and escalates issues if necessary 2) Configuration Manager :Configuration Manager is a web-based application used to configure and deploy the configuration to all brokers. 3) Monitor : Monitor is a web-based application used to monitor each Broker in the environment. This project has to be built up in java and protocol for file transfer in tcp/ip. Client does not want to use FTP. File Transfer seems very easy, until there are several processes who are waiting to pick the file up automatically. Several problems arise: How can we guarantee the file is received at the destination? If a file isn’t received the first time, we should try it again (even after a restart or power breakdown) ? How does the receiver knows the file that is received is complete? How can we transfer multiple files synchronously? How can we protect the bandwidth, so file transfer isn’t blocking other processes? How does one interoperate between multiple OS platforms? What about authentication? How can we monitor het workflow? Auditing / logging Archiving Can you please provide answer to some of these? Thanks

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  • Java NullPointerException In the constructor's class

    - by AndreaF
    I have made a Java class where I have defined a constructor and some methods but I get a NullPointer Exception, and I don't know how I could fix It. public class Job { String idJob; int time; int timeRun; Job j1; List<Job> startBeforeStart; List<Job> restricted; Job(String idJob, int time){ this.idJob=idJob; this.time=time; } public boolean isRestricted() { return restricted.size() != 0; } public void startsBeforeStartOf(Job job){ startBeforeStart.add(job); job.restricted.add(this); } public void startsAfterStartOf(Job job){ job.startsBeforeStartOf(this); } public void checkRestrictions(){ if (!isRestricted()){ System.out.println("+\n"); } else{ Iterator<Job> itR = restricted.iterator(); while(itR.hasNext()){ Job j1 = itR.next(); if(time>timeRun){ System.out.println("-\n"); time--; } else { restricted.remove(j1); } } } } @Override public boolean equals(Object obj) { return obj instanceof Job && ((Job) obj).idJob.equals(idJob); } public void run() { timeRun++; } } PS Looking in a forum a user says that to fix the error I should make an ArrayList inside the constructor (without modify the received parameters that should remain String id and int time), but I haven't understand what He mean.

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  • Transferring HashMap between client and server using Sockets (JAVA)

    - by sar
    I am working on a JAVA project in which there are multiple terminals. These terminals act as client and servers. For example if there are 3 terminals A,B and C.Then at any given point in time one of them say A, will be a client making broadcast request. The other two terminals, B and C, will reply. I am using sockets to make them communicate. Once the reply is received from all the other terminals A will check the pool of channels to see if any one of the channel is free. It takes up the free channel and making it availabilty false. The channelpool is implemented using HashMAp: HashMap channelpool = new HashMap(); channelpool = 1=true, 2=true, 3=false, 4=true, 5=true, 6=true, 7=true, 8=true, 9=true, 10=true So initially all the channels are true, any terminal can take any channel. But once the channel is taken it is set to false for the period of use and then reset to true. Now this Hashmap has to be shared among the distributed terminals. Also it should be kept up to date. I can not used a shared resource among the terminals to store the HashMap.Can someone tell me an easy way to transfer the HashMap between the terminals. I will appreciate if someone could point me to a website which discusses this.

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  • Sorting arrays in java

    - by user360706
    Write a static method in Java : public static void sortByFour (int[] arr) That receives as a paramater an array full of non-negative numbers (zero or positive) and sorts the array in the following way : In the beginning of the array all the numbers that devide by four without a remainder will appear. After them all the numbers in the array that devide by 4 with a remainder of 1 will appear. After them all the numbers in the array that devide by 4 with a remainder of 2 will appear. In the end of the array all the rest numbers (those who divide by 4 with the remainder 3) will appear. (The order of the numbers in each group doesn't matter) The method must be the most efficient it can. This is what I wrote but unfortunately it doesn't work well... :( public static void swap( int[] arr, int left, int right ) { int temp = arr[left]; arr[left] = arr[right]; arr[right] = temp; } public static void sortByFour( int[] arr ) { int left = 0; int right = ( arr.length - 1 ); int mid = ( arr.length / 2 ); while ( left < right ) { if ( ( arr[left] % 4 ) > ( arr[right] % 4 ) ) { swap( arr, left, right ); right--; } if ( ( arr[left] % 4 ) == ( arr[right] % 4 ) ) left++; else left++; } } Can someone please help me by fixing my code so that it will work well or rewriting it?

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  • Can not issue data manipulation statements with executeQuery in java

    - by user225269
    I'm trying to insert records in mysql database using java, What do I place in this code so that I could insert records: String id; String name; String school; String gender; String lang; Scanner inputs = new Scanner(System.in); System.out.println("Input id:"); id=inputs.next(); System.out.println("Input name:"); name=inputs.next(); System.out.println("Input school:"); school= inputs.next(); System.out.println("Input gender:"); gender= inputs.next(); System.out.println("Input lang:"); lang=inputs.next(); Class.forName("com.mysql.jdbc.Driver"); Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/employee_record", "root", "MyPassword"); PreparedStatement statement = con.prepareStatement("insert into employee values('id', 'name', 'school', 'gender', 'lang');"); statement.executeUpdate();

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  • Combining Java hashcodes into a "master" hashcode

    - by Nick Wiggill
    I have a vector class with hashCode() implemented. It wasn't written by me, but uses 2 prime numbers by which to multiply the 2 vector components before XORing them. Here it is: /*class Vector2f*/ ... public int hashCode() { return 997 * ((int)x) ^ 991 * ((int)y); //large primes! } ...As this is from an established Java library, I know that it works just fine. Then I have a Boundary class, which holds 2 vectors, "start" and "end" (representing the endpoints of a line). The values of these 2 vectors are what characterize the boundary. /*class Boundary*/ ... public int hashCode() { return 1013 * (start.hashCode()) ^ 1009 * (end.hashCode()); } Here I have attempted to create a good hashCode() for the unique 2-tuple of vectors (start & end) constituting this boundary. My question: Is this hashCode() implementation going to work? (Note that I have used 2 different prime numbers in the latter hashCode() implementation; I don't know if this is necessary but better to be safe than sorry when trying to avoid common factors, I guess -- since I presume this is why primes are popular for hashing functions.)

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  • Java - problems iterating through an ArrayList

    - by cc0
    Ok so I have an ArrayList (arrBok), which is full of book objects (the code is in Norwegian, so pay no attention to that please). I want to make a public method which iterates through all the objects in the arraylist. When I execute the code, it just seems to run in an infinite loop, not producing any return values. Here is the relevant (I hope, because there are a couple of other classes involved) part of the code; public String listAll() { itr = arrBok.iterator(); while (itr.hasNext()) { i++; } return "lol"; } This code does nothing useful, but I just want to see if it can iterate through it successfully. What I have tried so far; Tested if the bokArr (arraylist) is empty, which it's not. It has 4 objects inside of it. Return the toString() method of the itr, with the following result; java.util.AbstractList$Itr@173a10f // <-- not sure if this would be relevant to anything return itr.next().toString(); <-- // which seems to return the first object in the array, does that make sense?

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  • Project Euler, Problem 10 java solution now working

    - by Dennis S
    Hi, I'm trying to find the sum of the prime numbers < 2'000'000. This is my solution in java but I can't seem get the correct answer. Please give some input on what could be wrong and general advice on the code is appreciated. Printing 'sum' gives: 1308111344, which is incorrect. /* The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17. Find the sum of all the primes below two million. */ class Helper{ public void run(){ Integer sum = 0; for(int i = 2; i < 2000000; i++){ if(isPrime(i)) sum += i; } System.out.println(sum); } private boolean isPrime(int nr){ if(nr == 2) return true; else if(nr == 1) return false; if(nr % 2 == 0) return false; for(int i = 3; i < Math.sqrt(nr); i += 2){ if(nr % i == 0) return false; } return true; } } class Problem{ public static void main(String[] args){ Helper p = new Helper(); p.run(); } }

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  • Java reflection appropriateness

    - by jsn
    This may be a fairly subjective question, but maybe not. My application contains a bunch of forms that are displayed to the user at different times. Each form is a class of its own. Typically the user clicks a button, which launches a new form. I have a convenience function that builds these buttons, you call it like this: buildButton( "button text", new SelectionAdapter() { @Override public void widgetSelected( SelectionEvent e ) { showForm( new TasksForm( args... ) ); } } ); I do this dozens of times, and it's really cumbersome having to make a SelectionAdapter every time. Really all I need for the button to know is what class to instantiate when it's clicked and what arguments to give the constructor, so I built a function that I call like this instead: buildButton( "button text", TasksForm.class, args... ); Where args is an arbitrary list of objects that you could use to instantiate TasksForm normally. It uses reflection to get a constructor from the class, match the argument list, and build an instance when it needs to. Most of the time I don't have to pass any arguments to the constructor at all. The downside is obviously that if I'm passing a bad set of arguments, it can't detect that at compilation time, so if it fails, a dialog is displayed at runtime. But it won't normally fail, and it'll be easy to debug if it does. I think this is much cleaner because I come from languages where the use of function and class literals is pretty common. But if you're a normal Java programmer, would seeing this freak you out, or would you appreciate not having to scan a zillion SelectionAdapters?

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