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  • How to avoid concurrent execution of a time-consuming task without blocking?

    - by Diego V
    I want to efficiently avoid concurrent execution of a time-consuming task in a heavily multi-threaded environment without making threads wait for a lock when another thread is already running the task. Instead, in that scenario, I want them to gracefully fail (i.e. skip its attempt to execute the task) as fast as possible. To illustrate the idea considerer this unsafe (has race condition!) code: private static boolean running = false; public void launchExpensiveTask() { if (running) return; // Do nothing running = true; try { runExpensiveTask(); } finally { running = false; } } I though about using a variation of Double-Checked Locking (consider that running is a primitive 32-bit field, hence atomic, it could work fine even for Java below 5 without the need of volatile). It could look like this: private static boolean running = false; public void launchExpensiveTask() { if (running) return; // Do nothing synchronized (ThisClass.class) { if (running) return; running = true; try { runExpensiveTask(); } finally { running = false; } } } Maybe I should also use a local copy of the field as well (not sure now, please tell me). But then I realized that anyway I will end with an inner synchronization block, that still could hold a thread with the right timing at monitor entrance until the original executor leaves the critical section (I know the odds usually are minimal but in this case we are thinking in several threads competing for this long-running resource). So, could you think in a better approach?

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  • How to improve the builder pattern?

    - by tangens
    Motivation Recently I searched for a way to initialize a complex object without passing a lot of parameter to the constructor. I tried it with the builder pattern, but I don't like the fact, that I'm not able to check at compile time if I really set all needed values. Traditional builder pattern When I use the builder pattern to create my Complex object, the creation is more "typesafe", because it's easier to see what an argument is used for: new ComplexBuilder() .setFirst( "first" ) .setSecond( "second" ) .setThird( "third" ) ... .build(); But now I have the problem, that I can easily miss an important parameter. I can check for it inside the build() method, but that is only at runtime. At compile time there is nothing that warns me, if I missed something. Enhanced builder pattern Now my idea was to create a builder, that "reminds" me if I missed a needed parameter. My first try looks like this: public class Complex { private String m_first; private String m_second; private String m_third; private Complex() {} public static class ComplexBuilder { private Complex m_complex; public ComplexBuilder() { m_complex = new Complex(); } public Builder2 setFirst( String first ) { m_complex.m_first = first; return new Builder2(); } public class Builder2 { private Builder2() {} Builder3 setSecond( String second ) { m_complex.m_second = second; return new Builder3(); } } public class Builder3 { private Builder3() {} Builder4 setThird( String third ) { m_complex.m_third = third; return new Builder4(); } } public class Builder4 { private Builder4() {} Complex build() { return m_complex; } } } } As you can see, each setter of the builder class returns a different internal builder class. Each internal builder class provides exactly one setter method and the last one provides only a build() method. Now the construction of an object again looks like this: new ComplexBuilder() .setFirst( "first" ) .setSecond( "second" ) .setThird( "third" ) .build(); ...but there is no way to forget a needed parameter. The compiler wouldn't accept it. Optional parameters If I had optional parameters, I would use the last internal builder class Builder4 to set them like a "traditional" builder does, returning itself. Questions Is this a well known pattern? Does it have a special name? Do you see any pitfalls? Do you have any ideas to improve the implementation - in the sense of fewer lines of code?

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  • Averaging initial values for rolling series

    - by Dave Jarvis
    Question Given a maximum sliding window size of 40 (i.e., the set of numbers in the list cannot exceed 40), what is the calculation to ensure a smooth averaging transition as the set size grows from 1 to 40? Problem Description Creating a trend line for a set of data has skewed initial values. The complete set of values is unknown at runtime: they are provided one at a time. It seems like a reverse-weighted average is required so that the initial values are averaged differently. In the image below the leftmost data for the trend line are incorrectly averaged. Current Solution Created a new type of ArrayList subclass that calculates the appropriate values and ensures its size never goes beyond the bounds of the sliding window: /** * A list of Double values that has a maximum capacity enforced by a sliding * window. Can calculate the average of its values. */ public class AveragingList extends ArrayList<Double> { private float slidingWindowSize = 0.0f; /** * The initial capacity is used for the sliding window size. * @param slidingWindowSize */ public AveragingList( int slidingWindowSize ) { super( slidingWindowSize ); setSlidingWindowSize( ( float )slidingWindowSize ); } public boolean add( Double d ) { boolean result = super.add( d ); // Prevent the list from exceeding the maximum sliding window size. // if( size() > getSlidingWindowSize() ) { remove( 0 ); } return result; } /** * Calculate the average. * * @return The average of the values stored in this list. */ public double average() { double result = 0.0; int size = size(); for( Double d: this ) { result += d.doubleValue(); } return (double)result / (double)size; } /** * Changes the maximum number of numbers stored in this list. * * @param slidingWindowSize New maximum number of values to remember. */ public void setSlidingWindowSize( float slidingWindowSize ) { this.slidingWindowSize = slidingWindowSize; } /** * Returns the number used to determine the maximum values this list can * store before it removes the first entry upon adding another value. * @return The maximum number of numbers stored in this list. */ public float getSlidingWindowSize() { return slidingWindowSize; } } Resulting Image Example Input The data comes into the function one value at a time. For example, data points (Data) and calculated averages (Avg) typically look as follows: Data: 17.0 Avg : 17.0 Data: 17.0 Avg : 17.0 Data: 5.0 Avg : 13.0 Data: 5.0 Avg : 11.0  Related Sites The following pages describe moving averages, but typically when all (or sufficient) data is known: http://www.cs.princeton.edu/introcs/15inout/MovingAverage.java.html http://stackoverflow.com/questions/2161815/r-zoo-series-sliding-window-calculation http://taragana.blogspot.com/ http://www.dreamincode.net/forums/index.php?showtopic=92508 http://blogs.sun.com/nickstephen/entry/dtrace_and_moving_rolling_averages

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  • Is there an equivalent to Lisp's "runtime" primitive in Scheme?

    - by Bill the Lizard
    According to SICP section 1.2.6, exercise 1.22: Most Lisp implementations include a primitive called runtime that returns an integer that specifies the amount of time the system has been running (measured, for example, in microseconds). I'm using DrScheme, where runtime doesn't seem to be available, so I'm looking for a good substitute. I found in the PLT-Scheme Reference that there is a current-milliseconds primitive. Does anyone know if there's a timer in Scheme with better resolution?

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  • References between Spring beans when using a NameSpaceHandler

    - by teabot
    I'm trying to use a Spring context namespace to build some existing configuration objects in an application. I have defined a context and pretty much have if working satisfactorily - however, I'd like one bean defined by my namespace to implicitly reference another: Consider the class named 'Node': public Class Node { private String aField; private Node nextNode; public Node(String aField, Node nextNode) { ... } Now in my Spring context I have something like so: <myns:container> <myns:node aField="nodeOne"/> <myns:node aField="nodeTwo"/> </myns:container> Now I'd like nodeOne.getNode() == nodeTwo to be true. So that nodeOne.getNode() and nodeTwo refer to the same bean instance. These are pretty much the relevant parts I have in my AbstractBeanDefinitionParser: public AbstractBeanDefinition parseInternal(Element element, ParserContext parserContext) { ... BeanDefinitionBuilder containerFactory = BeanDefinitionBuilder.rootBeanDefinition(ContainerFactoryBean.class); List<BeanDefinition> containerNodes = Lists.newArrayList(); String previousNodeBeanName; // iterate backwards over the 'node' elements for (int i = nodeElements.size() - 1; i >= 0; --i) { BeanDefinitionBuilder node = BeanDefinitionBuilder.rootBeanDefinition(Node.class); node.setScope(BeanDefinition.SCOPE_SINGLETON); String nodeField = nodeElements.getAttribute("aField"); node.addConstructorArgValue(nodeField); if (previousNodeBeanName != null) { node.addConstructorArgValue(new RuntimeBeanReference(previousNodeBeanName)); } else { node.addConstructorArgValue(null); } BeanDefinition nodeDefinition = node.getBeanDefinition(); previousNodeBeanName = "inner-node-" + nodeField; parserContext.getRegistry().registerBeanDefinition(previousNodeBeanName, nodeDefinition); containerNodes.add(node); } containerFactory.addPropertyValue("nodes", containerNodes); } When the application context is created my Node instances are created and recognized as singletons. Furthermore, the nextNode property is populated with a Node instance with the previous nodes configuration - however, it isn't the same instance. If I output a log message in Node's constructor I see two instances created for each node bean definition. I can think of a few workarounds myself but I'm keen to use the existing model. So can anyone tell me how I can pass these runtime bean references so that I get the correct singleton behaviour for my Node instances?

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  • MS Runtime required for app to run, how can I include with setup?

    - by JPJedi
    My application requires access to be installed on the computer or at least the MS Access runtime. Is their a way to include that with the application to check for that component/resource or install it if it isn't? Or would it just be easier to include a link to tell the user where to get the runtime if the error happens? I am using Visual Studio 2008 and the windows form app is written in VB.net. I am currently using click once for the deployment. Thanks

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  • Does Windows 8 RTM Support VB6 (SP6) Runtime files? If so, which ones?

    - by user51047
    Basically, I'm trying to find out which of the following files come packaged with the Windows 8 RTM (that is, the final version). Just to be clear, we're not wanting to know if any of the runtime files (listed below) are or were included with any of the previous versions (Beta, CTP, RS etc) or releases of Windows 8 - we are just interested in this compatibility question as far as Windows 8 RTM (Final Version) is concerned. In addition, if possible, we would also like to know which of the below files (if any) come shipped and registered with the Windows 8 RT (on ARM) version. As far as the ARM version is concerned, you're welcome to base your answer on the latest version of Windows 8 RT (on ARM) that is available at the date and time your answer is posted. (This will also serve to future-proof this question as additional releases or versions of Windows 8 and Windows 8 RT on ARM come out). Here are the list of files (which are basically the VB6 SP6 runtime files): File name Version Size Asycfilt.dll 2.40.4275.1 144 KB (147,728 bytes) Comcat.dll 4.71.1460.1 21.7 KB (22,288 bytes) Msvbvm60.dll 6.0.97.82 1.32 MB (1,386,496 bytes) Oleaut32.dll 2.40.4275.1 584 KB (598,288 bytes) Olepro32.dll 5.0.4275.1 160 KB (164,112 bytes) Stdole2.tlb 2.40.4275.1 17.5 KB (17,920 bytes) Of course, the most important file in there is MSVBVM60.DLL, so if you cannot provide details for all files relating to both Windows Releases, then basing the answer on as many of the files possible would also be useful. Thank you for reading and for your anticipated assistance in putting this question/answer on record.

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  • Optimizing a lot of Scanner.findWithinHorizon(pattern, 0) calls

    - by darvids0n
    I'm building a process which extracts data from 6 csv-style files and two poorly laid out .txt reports and builds output CSVs, and I'm fully aware that there's going to be some overhead searching through all that whitespace thousands of times, but I never anticipated converting about about 50,000 records would take 12 hours. Excerpt of my manual matching code (I know it's horrible that I use lists of tokens like that, but it was the best thing I could think of): public static String lookup(List<String> tokensBefore, List<String> tokensAfter) { String result = null; while(_match(tokensBefore)) { // block until all input is read if(id.hasNext()) { result = id.next(); // capture the next token that matches if(_matchImmediate(tokensAfter)) // try to match tokensAfter to this result return result; } else return null; // end of file; no match } return null; // no matches } private static boolean _match(List<String> tokens) { return _match(tokens, true); } private static boolean _match(List<String> tokens, boolean block) { if(tokens != null && !tokens.isEmpty()) { if(id.findWithinHorizon(tokens.get(0), 0) == null) return false; for(int i = 1; i <= tokens.size(); i++) { if (i == tokens.size()) { // matches all tokens return true; } else if(id.hasNext() && !id.next().matches(tokens.get(i))) { break; // break to blocking behaviour } } } else { return true; // empty list always matches } if(block) return _match(tokens); // loop until we find something or nothing else return false; // return after just one attempted match } private static boolean _matchImmediate(List<String> tokens) { if(tokens != null) { for(int i = 0; i <= tokens.size(); i++) { if (i == tokens.size()) { // matches all tokens return true; } else if(!id.hasNext() || !id.next().matches(tokens.get(i))) { return false; // doesn't match, or end of file } } return false; // we have some serious problems if this ever gets called } else { return true; // empty list always matches } } Basically wondering how I would work in an efficient string search (Boyer-Moore or similar). My Scanner id is scanning a java.util.String, figured buffering it to memory would reduce I/O since the search here is being performed thousands of times on a relatively small file. The performance increase compared to scanning a BufferedReader(FileReader(File)) was probably less than 1%, the process still looks to be taking a LONG time. I've also traced execution and the slowness of my overall conversion process is definitely between the first and last like of the lookup method. In fact, so much so that I ran a shortcut process to count the number of occurrences of various identifiers in the .csv-style files (I use 2 lookup methods, this is just one of them) and the process completed indexing approx 4 different identifiers for 50,000 records in less than a minute. Compared to 12 hours, that's instant. Some notes (updated): I don't necessarily need the pattern-matching behaviour, I only get the first field of a line of text so I need to match line breaks or use Scanner.nextLine(). All ID numbers I need start at position 0 of a line and run through til the first block of whitespace, after which is the name of the corresponding object. I would ideally want to return a String, not an int locating the line number or start position of the result, but if it's faster then it will still work just fine. If an int is being returned, however, then I would now have to seek to that line again just to get the ID; storing the ID of every line that is searched sounds like a way around that. Anything to help me out, even if it saves 1ms per search, will help, so all input is appreciated. Thankyou! Usage scenario 1: I have a list of objects in file A, who in the old-style system have an id number which is not in file A. It is, however, POSSIBLY in another csv-style file (file B) or possibly still in a .txt report (file C) which each also contain a bunch of other information which is not useful here, and so file B needs to be searched through for the object's full name (1 token since it would reside within the second column of any given line), and then the first column should be the ID number. If that doesn't work, we then have to split the search token by whitespace into separate tokens before doing a search of file C for those tokens as well. Generalised code: String field; for (/* each record in file A */) { /* construct the rest of this object from file A info */ // now to find the ID, if we can List<String> objectName = new ArrayList<String>(1); objectName.add(Pattern.quote(thisObject.fullName)); field = lookup(objectSearchToken, objectName); // search file B if(field == null) // not found in file B { lookupReset(false); // initialise scanner to check file C objectName.clear(); // not using the full name String[] tokens = thisObject.fullName.split(id.delimiter().pattern()); for(String s : tokens) objectName.add(Pattern.quote(s)); field = lookup(objectSearchToken, objectName); // search file C lookupReset(true); // back to file B } else { /* found it, file B specific processing here */ } if(field != null) // found it in B or C thisObject.ID = field; } The objectName tokens are all uppercase words with possible hyphens or apostrophes in them, separated by spaces. Much like a person's name. As per a comment, I will pre-compile the regex for my objectSearchToken, which is just [\r\n]+. What's ending up happening in file C is, every single line is being checked, even the 95% of lines which don't contain an ID number and object name at the start. Would it be quicker to use ^[\r\n]+.*(objectname) instead of two separate regexes? It may reduce the number of _match executions. The more general case of that would be, concatenate all tokensBefore with all tokensAfter, and put a .* in the middle. It would need to be matching backwards through the file though, otherwise it would match the correct line but with a huge .* block in the middle with lots of lines. The above situation could be resolved if I could get java.util.Scanner to return the token previous to the current one after a call to findWithinHorizon. I have another usage scenario. Will put it up asap.

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  • .exe is not created when using launch4j and maven

    - by Ismail Sen
    I'm trying to create an exe file for my JAVA project using launch4j and Maven. Here is my pom.xml <build> <pluginManagement> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>3.0</version> <configuration> <source>1.7</source> <target>1.7</target> </configuration> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-jar-plugin</artifactId> <version>2.3.2</version> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-assembly-plugin</artifactId> <version>2.4</version> <configuration> <descriptorRefs> <descriptortRef>jar-with-dependencies</descriptortRef> </descriptorRefs> <archive> <manifest> <mainClass>dev.main.App</mainClass> </manifest> </archive> </configuration> <executions> <execution> <id>make-assembly</id> <phase>package</phase> <goals> <goal>single</goal> </goals> </execution> </executions> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-shade-plugin</artifactId> <version>1.7.1</version> <executions> <execution> <phase>package</phase> <goals> <goal>shade</goal> </goals> </execution> </executions> <configuration> <shadedArtifactAttached>true</shadedArtifactAttached> <shadedClassifierName>shaded</shadedClassifierName> <transformers> <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer"> <mainClass>dev.main.App</mainClass> </transformer> </transformers> </configuration> </plugin> <plugin> <groupId>com.akathist.maven.plugins.launch4j</groupId> <artifactId>launch4j-maven-plugin</artifactId> <version>1.5.1</version> <executions> <execution> <id>l4j-clui</id> <phase>package</phase> <goals> <goal>launch4j</goal> </goals> <configuration> <headerType>console</headerType> <jar>${project.build.directory}/target/App-jar-with-dependencies.jar</jar> <outfile>${project.build.directory}/target/App.exe</outfile> <downloadUrl>http://java.com/download</downloadUrl> <classPath> <mainClass>dev.main.App</mainClass> </classPath> <jre> <minVersion>1.6.0</minVersion> <jdkPreference>preferJre</jdkPreference> </jre> <versionInfo> <fileVersion>1.0.0.0</fileVersion> <txtFileVersion>${project.version}</txtFileVersion> <fileDescription>${project.name}</fileDescription> <copyright>C</copyright> <productVersion>1.0.0.0</productVersion> <txtProductVersion>1.0.0.0</txtProductVersion> <productName>${project.name}</productName> <internalName>AppName</internalName> <originalFilename>App.exe</originalFilename> </versionInfo> </configuration> </execution> </executions> </plugin> </plugins> </pluginManagement> </build> I run : mvn clean compile assembly:single to create my jar app with all Maven dependencies. To create the .exe I do : mvn package but nothing is created under target folder. Am I missing a goal or a configuration ? Ismail

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  • migrating Solaris to RH: network latency issue, tcp window size & other tcp parameters

    - by Bastien
    Hello I have a client/server app (Java) that I'm migrating from Solaris to RH Linux. since I started running it in RH, I noticed some issues related to latency. I managed to isolate the problem that looks like this: client sends 5 messages (32 bytes each) in a row (same application timestamp) to the server. server echos messages. client receives replies and prints round trip time for each msg. in Solaris, all is well: I get ALL 5 replies at the same time, roughly 80ms after having sent original messages (client & server are several thousands miles away from each other: my ping RTT is 80ms, all normal). in RH, first 3 messages are echoed normally (they arrive 80ms after they've been sent), however the following 2 arrive 80ms later (so total 160ms RTT). the pattern is always the same. clearly looked like a TCP problem. on my solaris box, I had previously configured the tcp stack with 2 specific options: disable nagle algorithm globally set tcp_deferred_acks_max to 0 on RH, it's not possible to disable nagle globally, but I disabled it on all of my apps' sockets (TCP_NODELAY). so I started playing with tcpdump (on the server machine), and compared both outputs: SOLARIS: 22 2.085645 client server TCP 56150 > 6006 [PSH, ACK] Seq=111 Ack=106 Win=66672 Len=22 "MSG_1 RCV" 23 2.085680 server client TCP 6006 > 56150 [ACK] Seq=106 Ack=133 Win=50400 Len=0 24 2.085908 client server TCP 56150 > 6006 [PSH, ACK] Seq=133 Ack=106 Win=66672 Len=22 "MSG_2 RCV" 25 2.085925 server client TCP 6006 > 56150 [ACK] Seq=106 Ack=155 Win=50400 Len=0 26 2.086175 client server TCP 56150 > 6006 [PSH, ACK] Seq=155 Ack=106 Win=66672 Len=22 "MSG_3 RCV" 27 2.086192 server client TCP 6006 > 56150 [ACK] Seq=106 Ack=177 Win=50400 Len=0 28 2.086243 server client TCP 6006 > 56150 [PSH, ACK] Seq=106 Ack=177 Win=50400 Len=21 "MSG_1 ECHO" 29 2.086440 client server TCP 56150 > 6006 [PSH, ACK] Seq=177 Ack=106 Win=66672 Len=22 "MSG_4 RCV" 30 2.086454 server client TCP 6006 > 56150 [ACK] Seq=127 Ack=199 Win=50400 Len=0 31 2.086659 server client TCP 6006 > 56150 [PSH, ACK] Seq=127 Ack=199 Win=50400 Len=21 "MSG_2 ECHO" 32 2.086708 client server TCP 56150 > 6006 [PSH, ACK] Seq=199 Ack=106 Win=66672 Len=22 "MSG_5 RCV" 33 2.086721 server client TCP 6006 > 56150 [ACK] Seq=148 Ack=221 Win=50400 Len=0 34 2.086947 server client TCP 6006 > 56150 [PSH, ACK] Seq=148 Ack=221 Win=50400 Len=21 "MSG_3 ECHO" 35 2.087196 server client TCP 6006 > 56150 [PSH, ACK] Seq=169 Ack=221 Win=50400 Len=21 "MSG_4 ECHO" 36 2.087500 server client TCP 6006 > 56150 [PSH, ACK] Seq=190 Ack=221 Win=50400 Len=21 "MSG_5 ECHO" 37 2.165390 client server TCP 56150 > 6006 [ACK] Seq=221 Ack=148 Win=66632 Len=0 38 2.166314 client server TCP 56150 > 6006 [ACK] Seq=221 Ack=190 Win=66588 Len=0 39 2.364135 client server TCP 56150 > 6006 [ACK] Seq=221 Ack=211 Win=66568 Len=0 REDHAT: 17 2.081163 client server TCP 55879 > 6006 [PSH, ACK] Seq=111 Ack=106 Win=66672 Len=22 "MSG_1 RCV" 18 2.081178 server client TCP 6006 > 55879 [ACK] Seq=106 Ack=133 Win=5888 Len=0 19 2.081297 server client TCP 6006 > 55879 [PSH, ACK] Seq=106 Ack=133 Win=5888 Len=21 "MSG_1 ECHO" 20 2.081711 client server TCP 55879 > 6006 [PSH, ACK] Seq=133 Ack=106 Win=66672 Len=22 "MSG_2 RCV" 21 2.081761 client server TCP 55879 > 6006 [PSH, ACK] Seq=155 Ack=106 Win=66672 Len=22 "MSG_3 RCV" 22 2.081846 server client TCP 6006 > 55879 [PSH, ACK] Seq=127 Ack=177 Win=5888 Len=21 "MSG_2 ECHO" 23 2.081995 server client TCP 6006 > 55879 [PSH, ACK] Seq=148 Ack=177 Win=5888 Len=21 "MSG_3 ECHO" 24 2.082011 client server TCP 55879 > 6006 [PSH, ACK] Seq=177 Ack=106 Win=66672 Len=22 "MSG_4 RCV" 25 2.082362 client server TCP 55879 > 6006 [PSH, ACK] Seq=199 Ack=106 Win=66672 Len=22 "MSG_5 RCV" 26 2.082377 server client TCP 6006 > 55879 [ACK] Seq=169 Ack=221 Win=5888 Len=0 27 2.171003 client server TCP 55879 > 6006 [ACK] Seq=221 Ack=148 Win=66632 Len=0 28 2.171019 server client TCP 6006 > 55879 [PSH, ACK] Seq=169 Ack=221 Win=5888 Len=42 "MSG_4 ECHO + MSG_5 ECHO" 29 2.257498 client server TCP 55879 > 6006 [ACK] Seq=221 Ack=211 Win=66568 Len=0 so, I got confirmation things are not working correctly for RH: packet 28 is sent TOO LATE, it looks like the server is waiting for packet 27's ACK before doing anything. seems to me it's the most likely reason... then I realized that the "Win" parameters are different on Solaris & RH dumps: 50400 on Solaris, only 5888 on RH. that's another hint... I read the doc about the slide window & buffer window, and played around with the rcvBuffer & sendBuffer in java on my sockets, but never managed to change this 5888 value to anything else (I checked each time directly with tcpdump). does anybody know how to do this ? I'm having a hard time getting definitive information, as in some cases there's "auto-negotiation" that I might need to bypass, etc... I eventually managed to get only partially rid of my initial problem by setting the "tcp_slow_start_after_idle" parameter to 0 on RH, but it did not change the "win" parameter at all. the same problem was there for the first 4 groups of 5 messages, with TCP retransmission & TCP Dup ACK in tcpdump, then the problem disappeared altogether for all following groups of 5 messages. It doesn't seem like a very clean and/or generic solution to me. I'd really like to reproduce the exact same conditions under both OSes. I'll keep researching, but any help from TCP gurus would be greatly appreciated ! thanks !

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  • How to connect to bluetoothbee device using j2me?

    - by user1500412
    I developed a simple bluetooth connection application in j2me. I try it on emulator, both server and client can found each other, but when I deploy the application to blackberry mobile phone and connect to a bluetoothbee device it says service search no records. What could it be possibly wrong? is it j2me can not find a service in bluetoothbee? The j2me itself succeed to found the bluetoothbee device, but why it can not find the service? My code is below. What I don't understand is the UUID? how to set UUID for unknown source? since I didn't know the UUID for the bluetoothbee device. class SearchingDevice extends Canvas implements Runnable,CommandListener,DiscoveryListener{ //...... public SearchingDevice(MenuUtama midlet, Display display){ this.display = display; this.midlet = midlet; t = new Thread(this); t.start(); timer = new Timer(); task = new TestTimerTask(); /*--------------------Device List------------------------------*/ select = new Command("Pilih",Command.OK,0); back = new Command("Kembali",Command.BACK,0); btDevice = new List("Pilih Device",Choice.IMPLICIT); btDevice.addCommand(select); btDevice.addCommand(back); btDevice.setCommandListener(this); /*------------------Input Form---------------------------------*/ formInput = new Form("Form Input"); nama = new TextField("Nama","",50,TextField.ANY); umur = new TextField("Umur","",50,TextField.ANY); measure = new Command("Ukur",Command.SCREEN,0); gender = new ChoiceGroup("Jenis Kelamin",Choice.EXCLUSIVE); formInput.addCommand(back); formInput.addCommand(measure); gender.append("Pria", null); gender.append("Wanita", null); formInput.append(nama); formInput.append(umur); formInput.append(gender); formInput.setCommandListener(this); /*---------------------------------------------------------------*/ findDevice(); } /*----------------Gambar screen searching device---------------------------------*/ protected void paint(Graphics g) { g.setColor(0,0,0); g.fillRect(0, 0, getWidth(), getHeight()); g.setColor(255,255,255); g.drawString("Mencari Device", 20, 20, Graphics.TOP|Graphics.LEFT); if(this.counter == 1){ g.setColor(255,115,200); g.fillRect(20, 100, 20, 20); } if(this.counter == 2){ g.setColor(255,115,200); g.fillRect(20, 100, 20, 20); g.setColor(100,255,255); g.fillRect(60, 80, 20, 40); } if(this.counter == 3){ g.setColor(255,115,200); g.fillRect(20, 100, 20, 20); g.setColor(100,255,255); g.fillRect(60, 80, 20, 40); g.setColor(255,115,200); g.fillRect(100, 60, 20, 60); } if(this.counter == 4){ g.setColor(255,115,200); g.fillRect(20, 100, 20, 20); g.setColor(100,255,255); g.fillRect(60, 80, 20, 40); g.setColor(255,115,200); g.fillRect(100, 60, 20, 60); g.setColor(100,255,255); g.fillRect(140, 40, 20, 80); //display.callSerially(this); } } /*--------- Running Searching Screen ----------------------------------------------*/ public void run() { while(run){ this.counter++; if(counter > 4){ this.counter = 1; } try { Thread.sleep(1000); } catch (InterruptedException ex) { System.out.println("interrupt"+ex.getMessage()); } repaint(); } } /*-----------------------------cari device bluetooth yang -------------------*/ public void findDevice(){ try { devices = new java.util.Vector(); local = LocalDevice.getLocalDevice(); agent = local.getDiscoveryAgent(); local.setDiscoverable(DiscoveryAgent.GIAC); agent.startInquiry(DiscoveryAgent.GIAC, this); } catch (BluetoothStateException ex) { System.out.println("find device"+ex.getMessage()); } } /*-----------------------------jika device ditemukan--------------------------*/ public void deviceDiscovered(RemoteDevice rd, DeviceClass dc) { devices.addElement(rd); } /*--------------Selesai tes koneksi ke bluetooth server--------------------------*/ public void inquiryCompleted(int param) { switch(param){ case DiscoveryListener.INQUIRY_COMPLETED: //inquiry completed normally if(devices.size()>0){ //at least one device has been found services = new java.util.Vector(); this.findServices((RemoteDevice)devices.elementAt(0)); this.run = false; do_alert("Inquiry completed",4000); }else{ do_alert("No device found in range",4000); } break; case DiscoveryListener.INQUIRY_ERROR: do_alert("Inquiry error",4000); break; case DiscoveryListener.INQUIRY_TERMINATED: do_alert("Inquiry canceled",4000); break; } } /*-------------------------------Cari service bluetooth server----------------------------*/ public void findServices(RemoteDevice device){ try { // int[] attributes = {0x100,0x101,0x102}; UUID[] uuids = new UUID[1]; //alamat server uuids[0] = new UUID("F0E0D0C0B0A000908070605040302010",false); //uuids[0] = new UUID("8841",true); //menyiapkan device lokal local = LocalDevice.getLocalDevice(); agent = local.getDiscoveryAgent(); //mencari service dari server agent.searchServices(null, uuids, device, this); //server = (StreamConnectionNotifies)Connector.open(url.toString()); } catch (BluetoothStateException ex) { // ex.printStackTrace(); System.out.println("Errorx"+ex.getMessage()); } } /*---------------------------Pencarian service selesai------------------------*/ public void serviceSearchCompleted(int transID, int respCode) { switch(respCode){ case DiscoveryListener.SERVICE_SEARCH_COMPLETED: if(currentDevice == devices.size() - 1){ if(services.size() > 0){ this.run = false; display.setCurrent(btDevice); do_alert("Service found",4000); }else{ do_alert("The service was not found",4000); } }else{ currentDevice++; this.findServices((RemoteDevice)devices.elementAt(currentDevice)); } break; case DiscoveryListener.SERVICE_SEARCH_DEVICE_NOT_REACHABLE: do_alert("Device not Reachable",4000); break; case DiscoveryListener.SERVICE_SEARCH_ERROR: do_alert("Service search error",4000); break; case DiscoveryListener.SERVICE_SEARCH_NO_RECORDS: do_alert("No records return",4000); break; case DiscoveryListener.SERVICE_SEARCH_TERMINATED: do_alert("Inquiry canceled",4000); break; } } public void servicesDiscovered(int i, ServiceRecord[] srs) { for(int x=0; x<srs.length;x++) services.addElement(srs[x]); try { btDevice.append(((RemoteDevice)devices.elementAt(currentDevice)).getFriendlyName(false),null); } catch (IOException ex) { System.out.println("service discover"+ex.getMessage()); } } public void do_alert(String msg, int time_out){ if(display.getCurrent() instanceof Alert){ ((Alert)display.getCurrent()).setString(msg); ((Alert)display.getCurrent()).setTimeout(time_out); }else{ Alert alert = new Alert("Bluetooth"); alert.setString(msg); alert.setTimeout(time_out); display.setCurrent(alert); } } private String getData(){ System.out.println("getData"); String cmd=""; try { ServiceRecord service = (ServiceRecord)services.elementAt(btDevice.getSelectedIndex()); String url = service.getConnectionURL(ServiceRecord.NOAUTHENTICATE_NOENCRYPT, false); conn = (StreamConnection)Connector.open(url); DataInputStream in = conn.openDataInputStream(); int i=0; timer.schedule(task, 15000); char c1; while(time){ //while(((c1 = in.readChar())>0) && (c1 != '\n')){ //while(((c1 = in.readChar())>0) ){ c1 = in.readChar(); cmd = cmd + c1; //System.out.println(c1); // } } System.out.print("cmd"+cmd); if(time == false){ in.close(); conn.close(); } } catch (IOException ex) { System.err.println("Cant read data"+ex); } return cmd; } //timer task fungsinya ketika telah mencapai waktu yg dijadwalkan putus koneksi private static class TestTimerTask extends TimerTask{ public TestTimerTask() { } public void run() { time = false; } } }

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  • Traditional IO vs memory-mapped

    - by Senne
    I'm trying to illustrate the difference in performance between traditional IO and memory mapped files in java to students. I found an example somewhere on internet but not everything is clear to me, I don't even think all steps are nececery. I read a lot about it here and there but I'm not convinced about a correct implementation of neither of them. The code I try to understand is: public class FileCopy{ public static void main(String args[]){ if (args.length < 1){ System.out.println(" Wrong usage!"); System.out.println(" Correct usage is : java FileCopy <large file with full path>"); System.exit(0); } String inFileName = args[0]; File inFile = new File(inFileName); if (inFile.exists() != true){ System.out.println(inFileName + " does not exist!"); System.exit(0); } try{ new FileCopy().memoryMappedCopy(inFileName, inFileName+".new" ); new FileCopy().customBufferedCopy(inFileName, inFileName+".new1"); }catch(FileNotFoundException fne){ fne.printStackTrace(); }catch(IOException ioe){ ioe.printStackTrace(); }catch (Exception e){ e.printStackTrace(); } } public void memoryMappedCopy(String fromFile, String toFile ) throws Exception{ long timeIn = new Date().getTime(); // read input file RandomAccessFile rafIn = new RandomAccessFile(fromFile, "rw"); FileChannel fcIn = rafIn.getChannel(); ByteBuffer byteBuffIn = fcIn.map(FileChannel.MapMode.READ_WRITE, 0,(int) fcIn.size()); fcIn.read(byteBuffIn); byteBuffIn.flip(); RandomAccessFile rafOut = new RandomAccessFile(toFile, "rw"); FileChannel fcOut = rafOut.getChannel(); ByteBuffer writeMap = fcOut.map(FileChannel.MapMode.READ_WRITE,0,(int) fcIn.size()); writeMap.put(byteBuffIn); long timeOut = new Date().getTime(); System.out.println("Memory mapped copy Time for a file of size :" + (int) fcIn.size() +" is "+(timeOut-timeIn)); fcOut.close(); fcIn.close(); } static final int CHUNK_SIZE = 100000; static final char[] inChars = new char[CHUNK_SIZE]; public static void customBufferedCopy(String fromFile, String toFile) throws IOException{ long timeIn = new Date().getTime(); Reader in = new FileReader(fromFile); Writer out = new FileWriter(toFile); while (true) { synchronized (inChars) { int amountRead = in.read(inChars); if (amountRead == -1) { break; } out.write(inChars, 0, amountRead); } } long timeOut = new Date().getTime(); System.out.println("Custom buffered copy Time for a file of size :" + (int) new File(fromFile).length() +" is "+(timeOut-timeIn)); in.close(); out.close(); } } When exactly is it nececary to use RandomAccessFile? Here it is used to read and write in the memoryMappedCopy, is it actually nececary just to copy a file at all? Or is it a part of memorry mapping? In customBufferedCopy, why is synchronized used here? I also found a different example that -should- test the performance between the 2: public class MappedIO { private static int numOfInts = 4000000; private static int numOfUbuffInts = 200000; private abstract static class Tester { private String name; public Tester(String name) { this.name = name; } public long runTest() { System.out.print(name + ": "); try { long startTime = System.currentTimeMillis(); test(); long endTime = System.currentTimeMillis(); return (endTime - startTime); } catch (IOException e) { throw new RuntimeException(e); } } public abstract void test() throws IOException; } private static Tester[] tests = { new Tester("Stream Write") { public void test() throws IOException { DataOutputStream dos = new DataOutputStream( new BufferedOutputStream( new FileOutputStream(new File("temp.tmp")))); for(int i = 0; i < numOfInts; i++) dos.writeInt(i); dos.close(); } }, new Tester("Mapped Write") { public void test() throws IOException { FileChannel fc = new RandomAccessFile("temp.tmp", "rw") .getChannel(); IntBuffer ib = fc.map( FileChannel.MapMode.READ_WRITE, 0, fc.size()) .asIntBuffer(); for(int i = 0; i < numOfInts; i++) ib.put(i); fc.close(); } }, new Tester("Stream Read") { public void test() throws IOException { DataInputStream dis = new DataInputStream( new BufferedInputStream( new FileInputStream("temp.tmp"))); for(int i = 0; i < numOfInts; i++) dis.readInt(); dis.close(); } }, new Tester("Mapped Read") { public void test() throws IOException { FileChannel fc = new FileInputStream( new File("temp.tmp")).getChannel(); IntBuffer ib = fc.map( FileChannel.MapMode.READ_ONLY, 0, fc.size()) .asIntBuffer(); while(ib.hasRemaining()) ib.get(); fc.close(); } }, new Tester("Stream Read/Write") { public void test() throws IOException { RandomAccessFile raf = new RandomAccessFile( new File("temp.tmp"), "rw"); raf.writeInt(1); for(int i = 0; i < numOfUbuffInts; i++) { raf.seek(raf.length() - 4); raf.writeInt(raf.readInt()); } raf.close(); } }, new Tester("Mapped Read/Write") { public void test() throws IOException { FileChannel fc = new RandomAccessFile( new File("temp.tmp"), "rw").getChannel(); IntBuffer ib = fc.map( FileChannel.MapMode.READ_WRITE, 0, fc.size()) .asIntBuffer(); ib.put(0); for(int i = 1; i < numOfUbuffInts; i++) ib.put(ib.get(i - 1)); fc.close(); } } }; public static void main(String[] args) { for(int i = 0; i < tests.length; i++) System.out.println(tests[i].runTest()); } } I more or less see whats going on, my output looks like this: Stream Write: 653 Mapped Write: 51 Stream Read: 651 Mapped Read: 40 Stream Read/Write: 14481 Mapped Read/Write: 6 What is makeing the Stream Read/Write so unbelievably long? And as a read/write test, to me it looks a bit pointless to read the same integer over and over (if I understand well what's going on in the Stream Read/Write) Wouldn't it be better to read int's from the previously written file and just read and write ints on the same place? Is there a better way to illustrate it? I've been breaking my head about a lot of these things for a while and I just can't get the whole picture..

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  • Null-free "maps": Is a callback solution slower than tryGet()?

    - by David Moles
    In comments to "How to implement List, Set, and Map in null free design?", Steven Sudit and I got into a discussion about using a callback, with handlers for "found" and "not found" situations, vs. a tryGet() method, taking an out parameter and returning a boolean indicating whether the out parameter had been populated. Steven maintained that the callback approach was more complex and almost certain to be slower; I maintained that the complexity was no greater and the performance at worst the same. But code speaks louder than words, so I thought I'd implement both and see what I got. The original question was fairly theoretical with regard to language ("And for argument sake, let's say this language don't even have null") -- I've used Java here because that's what I've got handy. Java doesn't have out parameters, but it doesn't have first-class functions either, so style-wise, it should suck equally for both approaches. (Digression: As far as complexity goes: I like the callback design because it inherently forces the user of the API to handle both cases, whereas the tryGet() design requires callers to perform their own boilerplate conditional check, which they could forget or get wrong. But having now implemented both, I can see why the tryGet() design looks simpler, at least in the short term.) First, the callback example: class CallbackMap<K, V> { private final Map<K, V> backingMap; public CallbackMap(Map<K, V> backingMap) { this.backingMap = backingMap; } void lookup(K key, Callback<K, V> handler) { V val = backingMap.get(key); if (val == null) { handler.handleMissing(key); } else { handler.handleFound(key, val); } } } interface Callback<K, V> { void handleFound(K key, V value); void handleMissing(K key); } class CallbackExample { private final Map<String, String> map; private final List<String> found; private final List<String> missing; private Callback<String, String> handler; public CallbackExample(Map<String, String> map) { this.map = map; found = new ArrayList<String>(map.size()); missing = new ArrayList<String>(map.size()); handler = new Callback<String, String>() { public void handleFound(String key, String value) { found.add(key + ": " + value); } public void handleMissing(String key) { missing.add(key); } }; } void test() { CallbackMap<String, String> cbMap = new CallbackMap<String, String>(map); for (int i = 0, count = map.size(); i < count; i++) { String key = "key" + i; cbMap.lookup(key, handler); } System.out.println(found.size() + " found"); System.out.println(missing.size() + " missing"); } } Now, the tryGet() example -- as best I understand the pattern (and I might well be wrong): class TryGetMap<K, V> { private final Map<K, V> backingMap; public TryGetMap(Map<K, V> backingMap) { this.backingMap = backingMap; } boolean tryGet(K key, OutParameter<V> valueParam) { V val = backingMap.get(key); if (val == null) { return false; } valueParam.value = val; return true; } } class OutParameter<V> { V value; } class TryGetExample { private final Map<String, String> map; private final List<String> found; private final List<String> missing; public TryGetExample(Map<String, String> map) { this.map = map; found = new ArrayList<String>(map.size()); missing = new ArrayList<String>(map.size()); } void test() { TryGetMap<String, String> tgMap = new TryGetMap<String, String>(map); for (int i = 0, count = map.size(); i < count; i++) { String key = "key" + i; OutParameter<String> out = new OutParameter<String>(); if (tgMap.tryGet(key, out)) { found.add(key + ": " + out.value); } else { missing.add(key); } } System.out.println(found.size() + " found"); System.out.println(missing.size() + " missing"); } } And finally, the performance test code: public static void main(String[] args) { int size = 200000; Map<String, String> map = new HashMap<String, String>(); for (int i = 0; i < size; i++) { String val = (i % 5 == 0) ? null : "value" + i; map.put("key" + i, val); } long totalCallback = 0; long totalTryGet = 0; int iterations = 20; for (int i = 0; i < iterations; i++) { { TryGetExample tryGet = new TryGetExample(map); long tryGetStart = System.currentTimeMillis(); tryGet.test(); totalTryGet += (System.currentTimeMillis() - tryGetStart); } System.gc(); { CallbackExample callback = new CallbackExample(map); long callbackStart = System.currentTimeMillis(); callback.test(); totalCallback += (System.currentTimeMillis() - callbackStart); } System.gc(); } System.out.println("Avg. callback: " + (totalCallback / iterations)); System.out.println("Avg. tryGet(): " + (totalTryGet / iterations)); } On my first attempt, I got 50% worse performance for callback than for tryGet(), which really surprised me. But, on a hunch, I added some garbage collection, and the performance penalty vanished. This fits with my instinct, which is that we're basically talking about taking the same number of method calls, conditional checks, etc. and rearranging them. But then, I wrote the code, so I might well have written a suboptimal or subconsicously penalized tryGet() implementation. Thoughts?

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  • How to convert this procedural programming to object-oriented programming?

    - by manus91
    I have a source code that is needed to be converted by creating classes, objects and methods. So far, I've just done by converting the initial main into a separate class. But I don't know what to do with constructor and which variables are supposed to be private. This is the code : import java.util.*; public class Card{ private static void shuffle(int[][] cards){ List<Integer> randoms = new ArrayList<Integer>(); Random randomizer = new Random(); for(int i = 0; i < 8;) { int r = randomizer.nextInt(8)+1; if(!randoms.contains(r)) { randoms.add(r); i++; } } List<Integer> clonedList = new ArrayList<Integer>(); clonedList.addAll(randoms); Collections.shuffle(clonedList); randoms.addAll(clonedList); Collections.shuffle(randoms); int i=0; for(int r=0; r < 4; r++){ for(int c=0; c < 4; c++){ cards[r][c] = randoms.get(i); i++; } } } public static void play() throws InterruptedException { int ans = 1; int preview; int r1,c1,r2,c2; int[][] cards = new int[4][4]; boolean[][] cardstatus = new boolean[4][4]; boolean gameover = false; int moves; Scanner input = new Scanner(System.in); do{ moves = 0; shuffle(cards); System.out.print("Enter the time(0 to 5) in seconds for the preview of the answer : "); preview = input.nextInt(); while((preview<0) || (preview>5)){ System.out.print("Invalid time!! Re-enter time(0 - 5) : "); preview = input.nextInt(); } preview = 1000*preview; System.out.println(" "); for (int i =0; i<4;i++){ for (int j=0;j<4;j++){ System.out.print(cards[i][j]); System.out.print(" "); } System.out.println(""); System.out.println(""); } Thread.sleep(preview); for(int b=0;b<25;b++){ System.out.println(" "); } for(int r=0;r<4;r++){ for(int c=0;c<4;c++){ System.out.print("*"); System.out.print(" "); cardstatus[r][c] = false; } System.out.println(""); System.out.println(" "); } System.out.println(""); do{ do{ System.out.print("Please insert the first card row : "); r1 = input.nextInt(); while((r1<1) || (r1>4)){ System.out.print("Invalid coordinate!! Re-enter first card row : "); r1 = input.nextInt(); } System.out.print("Please insert the first card column : "); c1 = input.nextInt(); while((c1<1) || (c1>4)){ System.out.print("Invalid coordinate!! Re-enter first card column : "); c1 = input.nextInt(); } if(cardstatus[r1-1][c1-1] == true){ System.out.println("The card is already flipped!! Select another card."); System.out.println(""); } }while(cardstatus[r1-1][c1-1] != false); do{ System.out.print("Please insert the second card row : "); r2 = input.nextInt(); while((r2<1) || (r2>4)){ System.out.print("Invalid coordinate!! Re-enter second card row : "); r2 = input.nextInt(); } System.out.print("Please insert the second card column : "); c2 = input.nextInt(); while((c2<1) || (c2>4)){ System.out.print("Invalid coordinate!! Re-enter second card column : "); c2 = input.nextInt(); } if(cardstatus[r2-1][c2-1] == true){ System.out.println("The card is already flipped!! Select another card."); } if((r1==r2)&&(c1==c2)){ System.out.println("You can't select the same card twice!!"); continue; } }while(cardstatus[r2-1][c2-1] != false); r1--; c1--; r2--; c2--; System.out.println(""); System.out.println(""); System.out.println(""); for(int r=0;r<4;r++){ for(int c=0;c<4;c++){ if((r==r1)&&(c==c1)){ System.out.print(cards[r][c]); System.out.print(" "); } else if((r==r2)&&(c==c2)){ System.out.print(cards[r][c]); System.out.print(" "); } else if(cardstatus[r][c] == true){ System.out.print(cards[r][c]); System.out.print(" "); } else{ System.out.print("*"); System.out.print(" "); } } System.out.println(" "); System.out.println(" "); } System.out.println(""); if(cards[r1][c1] == cards[r2][c2]){ System.out.println("Cards Matched!!"); cardstatus[r1][c1] = true; cardstatus[r2][c2] = true; } else{ System.out.println("No cards match!!"); } Thread.sleep(2000); for(int b=0;b<25;b++){ System.out.println(""); } for(int r=0;r<4;r++){ for(int c=0;c<4;c++){ if(cardstatus[r][c] == true){ System.out.print(cards[r][c]); System.out.print(" "); } else{ System.out.print("*"); System.out.print(" "); } } System.out.println(""); System.out.println(" "); } System.out.println(""); System.out.println(""); System.out.println(""); gameover = true; for(int r=0;r<4;r++){ for( int c=0;c<4;c++){ if(cardstatus[r][c]==false){ gameover = false; break; } } if(gameover==false){ break; } } moves++; }while(gameover != true); System.out.println("Congratulations, you won!!"); System.out.println("It required " + moves + " moves to finish it."); System.out.println(""); System.out.print("Would you like to play again? (1=Yes / 0=No) : "); ans = input.nextInt(); }while(ans == 1); } } The main class is: import java.util.*; public class PlayCard{ public static void main(String[] args) throws InterruptedException{ Card game = new Card(); game.play(); } } Should I simplify the Card class by creating other classes? Through this code, my javadoc has no constructtor. So i need help on this!

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  • How can I update a Jtextarea once? (mysql side-?)

    - by user1294196
    Ok what I've been trying to do is figure out how to make it so when I press the search button on my program the code that is currently just being printed to the console will print to the text area I have. I can't figure out how to do this and I've searched google and still found no answer. And while I'm at it if anyone could help me figure out how to send this same line of information to a mysql database that would help greatly. package GTE; import java.awt.EventQueue; public class GTE { private JFrame frmGte; public String hashq = "..."; public String twtresults; public int refresh = 1; public static void main(String[] args) { java.awt.EventQueue.invokeLater(new Runnable() { public void run() { try { GTE window = new GTE(); window.frmGte.setVisible(true); } catch (Exception e) {} } }); } /** * Create the application. * @throws IOException * @throws FontFormatException */ public GTE(){ try { initialize(); } catch (FontFormatException e) {} catch (IOException e) {} } /** * Initialize the contents of the frame. * @throws IOException * @throws FontFormatException */ private void initialize() throws FontFormatException, IOException { frmGte = new JFrame(); frmGte.setResizable(false); frmGte.setTitle("GTE"); frmGte.setBounds(100, 100, 450, 390); frmGte.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); GridBagLayout gridBagLayout = new GridBagLayout(); gridBagLayout.columnWidths = new int[]{434, 0}; gridBagLayout.rowHeights = new int[]{21, 0, 0, 0, 0, 0, 0, 0, 0}; gridBagLayout.columnWeights = new double[]{0.0, Double.MIN_VALUE}; gridBagLayout.rowWeights = new double[]{0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, Double.MIN_VALUE}; frmGte.getContentPane().setLayout(gridBagLayout); JLabel GTETitle = new JLabel("Personal Tweet Extractor"); InputStream is = this.getClass().getResourceAsStream("ultraviolentbb_reg.ttf"); Font GTEFont = Font.createFont(Font.TRUETYPE_FONT,is); Font f = GTEFont.deriveFont(24f); GTETitle.setFont(f); GTETitle.setHorizontalAlignment(SwingConstants.CENTER); GridBagConstraints gbc_GTETitle = new GridBagConstraints(); gbc_GTETitle.insets = new Insets(0, 0, 5, 0); gbc_GTETitle.anchor = GridBagConstraints.NORTH; gbc_GTETitle.fill = GridBagConstraints.HORIZONTAL; gbc_GTETitle.gridx = 0; gbc_GTETitle.gridy = 0; frmGte.getContentPane().add(GTETitle, gbc_GTETitle); Label label_2 = new Label("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~"); GridBagConstraints gbc_label_2 = new GridBagConstraints(); gbc_label_2.insets = new Insets(0, 0, 5, 0); gbc_label_2.gridx = 0; gbc_label_2.gridy = 1; frmGte.getContentPane().add(label_2, gbc_label_2); JLabel SearchTweets = new JLabel("Search For Tweets With" + hashq + ":"); GridBagConstraints gbc_SearchTweets = new GridBagConstraints(); gbc_SearchTweets.insets = new Insets(0, 0, 5, 0); gbc_SearchTweets.gridx = 0; gbc_SearchTweets.gridy = 2; frmGte.getContentPane().add(SearchTweets, gbc_SearchTweets); JLabel label = new JLabel("#"); GridBagConstraints gbc_label = new GridBagConstraints(); gbc_label.insets = new Insets(0, 0, 5, 0); gbc_label.gridx = 0; gbc_label.gridy = 3; frmGte.getContentPane().add(label, gbc_label); JButton Search = new JButton("Start Search"); Search.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent evt) { TS(hashq); GTE.this.refresh = 0; try { nulll dialog = new nulll(); dialog.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE); dialog.setVisible(true); } catch (Exception e) {} } public void TS(String hashtag){ Twitter twitter = new TwitterFactory().getInstance(); try { System.out.println(hashtag); QueryResult result = twitter.search(new Query("#" + hashtag)); List<Tweet> tweets = result.getTweets(); for (Tweet tweet : tweets) { System.out.println("@" + tweet.getFromUser() + " : " + tweet.getText()); GTE.this.twtresults = ("@" + tweet.getFromUser() + " : " + tweet.getText()); } } catch (TwitterException te) { te.printStackTrace(); System.out.println("Failed to search tweets: " + te.getMessage()); System.exit(-1); } } }); TextField textField = new TextField(); textField.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent evt) { GTE.this.hashq = evt.getActionCommand(); } }); GridBagConstraints gbc_textField = new GridBagConstraints(); gbc_textField.ipadx = 99; gbc_textField.insets = new Insets(0, 0, 5, 0); gbc_textField.gridx = 0; gbc_textField.gridy = 4; frmGte.getContentPane().add(textField, gbc_textField); GridBagConstraints gbc_Search = new GridBagConstraints(); gbc_Search.insets = new Insets(0, 0, 5, 0); gbc_Search.gridx = 0; gbc_Search.gridy = 5; frmGte.getContentPane().add(Search, gbc_Search); Label label_1 = new Label("Search Results For Tweets With"); GridBagConstraints gbc_label_1 = new GridBagConstraints(); gbc_label_1.insets = new Insets(0, 0, 5, 0); gbc_label_1.gridx = 0; gbc_label_1.gridy = 6; frmGte.getContentPane().add(label_1, gbc_label_1); TextArea textArea = new TextArea(); textArea.setText(twtresults); textArea.setEditable(false); GridBagConstraints gbc_textArea = new GridBagConstraints(); gbc_textArea.gridx = 0; gbc_textArea.gridy = 7; frmGte.getContentPane().add(textArea, gbc_textArea); JMenuBar menuBar = new JMenuBar(); frmGte.setJMenuBar(menuBar); JMenu Filemenu = new JMenu("File"); menuBar.add(Filemenu); JMenuItem Exititem = new JMenuItem("Exit"); Exititem.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent evt) { System.exit(0); } }); Filemenu.add(Exititem); JMenu Helpmenu = new JMenu("Help"); menuBar.add(Helpmenu); JMenuItem Aboutitem = new JMenuItem("About"); Helpmenu.add(Aboutitem); } }

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  • In agile environment, how is bug tracking and iteration tracking consolidated.

    - by DXM
    This topic stemmed from my other question about management-imposed waterfall-like schedule. From the responses in the other thread, I gathered this much about what is generally advised: Each story should be completed with no bugs. Story is not closed until all bugs have been addressed. No news there and I think we can all agree with this. If at a later date QA (or worse yet a customer) finds a bug, the report goes into a bug tracking database and also becomes a story which should be prioritized just like all other work. Does this sum up general handling of bugs in agile environment? If yes, the part I'm curious about is how do teams handle tracking in two different systems? (unless most teams don't have different systems). I've read a lot of advice (including Joel's blog) on software development in general and specifically on importance of a good bug tracking tool. At the same time when you read books on agile methodology, none of them seem to cover this topic because in "pure" agile, you finish iteration with no bugs. Feels like there's a hole there somewhere. So how do real teams operate? To track iterations you'd use (whiteboard, Rally...), to track bugs you'd use something from another set of products (if you are lucky enough, you might even get stuck with HP Quality Center). Should there be 2 separate systems? If they are separate, do teams spend time creating import/sync functionality between them? What have you done in your company? Is bug tracking software even used? Or do you just go straight to creating a story?

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  • Web Development Environment: How to distribute edited hosts files over bunch of mac machines?

    - by Alex Reds
    I am doing some research to prepare some web development environment for our small(10ppl and growing) new office. User Case: For each new web project usually we create new alias on an Apache server someproject.companywebsite From my understanding in order to see this website locally for all the rest of our team(including mangers and directors) they will need to edit hosts file (e.g. "192.168.1.10 someproject.companywebsite"), and like that each time for a new project(can be 2-5 each week) Solution: And I looking for a solution how to edit this hosts file only once and distribute it over all mac machines in our network at once or much more flawlessly than poking around with each machine every time over and over again. Is that possible? Or that a very wrong way of doing that? Perhaps we better set up own local dns server and point to it our router? Though own dns server a bit concerns me because of might be some network interruption and others lags, if you know what I mean. Or perhaps there are another workflows for that? What's the best way for such things? So I'll be so grateful to hear some advices from experienced admins. I couldn't find that info on internet, so if you know where to read about it, point me in a right direction. Thank you in advance Alex

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  • Should we hire a new developer now, or wait until the code is refactored to make it suitable for a team environment?

    - by w0051977
    I support and develop a large system that uses various technologies e.g. c++,.net,vb6 etc. I am a sole developer. I am debating whether now is the right time to approach my manager (who is not a developer) to ask if another developer can be recruited. I don't have any experience working in software teams. I have always been a sole developer. The concerns I have are: There is still a lot to do. Training another developer would take time and distract me from my duties. The company does not invest heavily in tools e.g. source control The code in this system needs to be refactored to introduce concepts such as interfaces, polymorphism etc, which are supported by methodologies such as Agile (I inherited the system about 12 months ago). I am gradually trying to refactor the code. I believe I have two options: Approach my manager now Wait until I have had time to refactor the code so it is more suitable for a team environment. Which option is best? I am hoping to hear from other developers who have been in my situation.

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  • Change font size in ListView - Android/Eclipse

    - by Soren
    How can I change the font size in a ListView element? In my main.xml file, I have tried several different values in for android:textSize (pt,px,sp,dp) and nothing seems to change it. Here is what I have currently for the in my main.xml: <ListView xmlns:android="http://schemas.android.com/apk/res/android" android:id="@android:id/list" android:textColor="#ffffff" android:background="#000080" android:layout_width="fill_parent" android:layout_height="wrap_content" android:clickable="true" android:dividerHeight="1px" android:layout_marginTop="5px" android:textSize="8px"/> Here is my Java: package com.SorenWinslow.TriumphHistory; import android.app.ListActivity; import android.os.Bundle; import android.widget.ArrayAdapter; public class TriumphHistory extends ListActivity { String[] HistoryList; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); ArrayAdapter<String> adapter; HistoryList = getResources().getStringArray(R.array.history); adapter = new ArrayAdapter<String> (this,android.R.layout.simple_list_item_1,HistoryList); setListAdapter(adapter); } }

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  • faster implementation of sum ( for Codility test )

    - by Oscar Reyes
    How can the following simple implementation of sum be faster? private long sum( int [] a, int begin, int end ) { if( a == null ) { return 0; } long r = 0; for( int i = begin ; i < end ; i++ ) { r+= a[i]; } return r; } EDIT Background is in order. Reading latest entry on coding horror, I came to this site: http://codility.com which has this interesting programming test. Anyway, I got 60 out of 100 in my submission, and basically ( I think ) is because this implementation of sum, because those parts where I failed are the performance parts. I'm getting TIME_OUT_ERROR's So, I was wondering if an optimization in the algorithm is possible. So, no built in functions or assembly would be allowed. This my be done in C, C++, C#, Java or pretty much in any other. EDIT As usual, mmyers was right. I did profile the code and I saw most of the time was spent on that function, but I didn't understand why. So what I did was to throw away my implementation and start with a new one. This time I've got an optimal solution [ according to San Jacinto O(n) -see comments to MSN below - ] This time I've got 81% on Codility which I think is good enough. The problem is that I didn't take the 30 mins. but around 2 hrs. but I guess that leaves me still as a good programmer, for I could work on the problem until I found an optimal solution: Here's my result. I never understood what is those "combinations of..." nor how to test "extreme_first"

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  • codility challenge, test case OK , Evaluation report Wrong Answer

    - by Hussein Fawzy
    the aluminium 2014 gives me wrong answer [3 , 9 , -6 , 7 ,-3 , 9 , -6 , -10] got 25 expected 28 but when i repeated the challenge with the same code and make case test it gives me the correct answer Your test case [3, 9, -6, 7, -3, 9, -6, -10] : NO RUNTIME ERRORS (returned value: 28) what is the wrong with it ??? the challenge :- A non-empty zero-indexed array A consisting of N integers is given. A pair of integers (P, Q), such that 0 = P = Q < N, is called a slice of array A. The sum of a slice (P, Q) is the total of A[P] + A[P+1] + ... + A[Q]. The maximum sum is the maximum sum of any slice of A. For example, consider array A such that: A[0] = 3 A[1] = 2 A[2] = -6 A[3] = 3 A[4] = 1 For example (0, 1) is a slice of A that has sum A[0] + A[1] = 5. This is the maximum sum of A. You can perform a single swap operation in array A. This operation takes two indices I and J, such that 0 = I = J < N, and exchanges the values of A[I] and A[J]. To goal is to find the maximum sum you can achieve after performing a single swap. For example, after swapping elements 2 and 4, you will get the following array A: A[0] = 3 A[1] = 2 A[2] = 1 A[3] = 3 A[4] = -6 After that, (0, 3) is a slice of A that has the sum A[0] + A[1] + A[2] + A[3] = 9. This is the maximum sum of A after a single swap. Write a function: class Solution { public int solution(int[] A); } that, given a non-empty zero-indexed array A of N integers, returns the maximum sum of any slice of A after a single swap operation. For example, given: A[0] = 3 A[1] = 2 A[2] = -6 A[3] = 3 A[4] = 1 the function should return 9, as explained above. and my code is :- import java.math.*; class Solution { public int solution(int[] A) { if(A.length == 1) return A[0]; else if (A.length==2) return A[0]+A[1]; else{ int finalMaxSum = A[0]; for (int l=0 ; l<A.length ; l++){ for (int k = l+1 ; k<A.length ; k++ ){ int [] newA = A; int temp = newA[l]; newA [l] = newA[k]; newA[k]=temp; int maxSum = newA[0]; int current_max = newA[0]; for(int i = 1; i < newA.length; i++) { current_max = Math.max(A[i], current_max + newA[i]); maxSum = Math.max(maxSum, current_max); } finalMaxSum = Math.max(finalMaxSum , maxSum); } } return finalMaxSum; } } } i don't know what's the wrong with it ??

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  • Merge method in MergeSort Algorithm .

    - by Tony
    I've seen many mergeSort implementations .Here is the version in Data Structures and Algorithms in Java (2nd Edition) by Robert Lafore : private void recMergeSort(long[] workSpace, int lowerBound,int upperBound) { if(lowerBound == upperBound) // if range is 1, return; // no use sorting else { // find midpoint int mid = (lowerBound+upperBound) / 2; // sort low half recMergeSort(workSpace, lowerBound, mid); // sort high half recMergeSort(workSpace, mid+1, upperBound); // merge them merge(workSpace, lowerBound, mid+1, upperBound); } // end else } // end recMergeSort() private void merge(long[] workSpace, int lowPtr, int highPtr, int upperBound) { int j = 0; // workspace index int lowerBound = lowPtr; int mid = highPtr-1; int n = upperBound-lowerBound+1; // # of items while(lowPtr <= mid && highPtr <= upperBound) if( theArray[lowPtr] < theArray[highPtr] ) workSpace[j++] = theArray[lowPtr++]; else workSpace[j++] = theArray[highPtr++]; while(lowPtr <= mid) workSpace[j++] = theArray[lowPtr++]; while(highPtr <= upperBound) workSpace[j++] = theArray[highPtr++]; for(j=0; j<n; j++) theArray[lowerBound+j] = workSpace[j]; } // end merge() One interesting thing about merge method is that , almost all the implementations didn't pass the lowerBound parameter to merge method . lowerBound is calculated in the merge . This is strange , since lowerPtr = mid + 1 ; lowerBound = lowerPtr -1 ; that means lowerBound = mid ; Why the author didn't pass mid to merge like merge(workSpace, lowerBound,mid, mid+1, upperBound); ? I think there must be a reason , otherwise I can't understand why an algorithm older than half a center ,and have all coincident in the such little detail.

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  • Retrieve GWT radiobutton value in servlet

    - by Florian d'Erfurth
    Hi, I'm having a headache figuring how to retrieve the gwt Radio Buttons values in the server side. Here is my UiBinder form: <g:FormPanel ui:field="form"><g:VerticalPanel ui:field="fruitPanel"> <g:RadioButton name="fruit">apple</g:RadioButton> <g:RadioButton name="fruit">banana</g:RadioButton> <g:SubmitButton>Submit</g:SubmitButton> ... Here is how i initialize the form: form.setAction("/submit"); form.setMethod(FormPanel.METHOD_POST); So i though i would have to do this on the servlet: fruit = req.getParameter("fruit") But of course this doesn't work, parameter fruit doesn't exist :/ Edit: Ok i get parameter fruit but it's always "on" I also did try to add the radio button in java with: RadioButton rb0 = new RadioButton("fruit", "apple"); RadioButton rb1 = new RadioButton("fruit", "banana"); fruitPanel.add(rb0); fruitPanel.add(rb1); So how should i do?

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