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  • Java - abstract class, equals(), and two subclasses

    - by msr
    Hello, I have an abstract class named Xpto and two subclasses that extend it named Person and Car. I have also a class named Test with main() and a method foo() that verifies if two persons or cars (or any object of a class that extends Xpto) are equals. Thus, I redefined equals() in both Person and Car classes. Two persons are equal when they have the same name and two cars are equal when they have the same registration. However, when I call foo() in the Test class I always get "false". I understand why: the equals() is not redefined in Xpto abstract class. So... how can I compare two persons or cars (or any object of a class that extends Xpto) in that foo() method? In summary, this is the code I have: public abstract class Xpto { } public class Person extends Xpto{ protected String name; public Person(String name){ this.name = name; } public boolean equals(Person p){ System.out.println("Person equals()?"); return this.name.compareTo(p.name) == 0 ? true : false; } } public class Car extends Xpto{ protected String registration; public Car(String registration){ this.registration = registration; } public boolean equals(Car car){ System.out.println("Car equals()?"); return this.registration.compareTo(car.registration) == 0 ? true : false; } } public class Teste { public static void foo(Xpto xpto1, Xpto xpto2){ if(xpto1.equals(xpto2)) System.out.println("xpto1.equals(xpto2) -> true"); else System.out.println("xpto1.equals(xpto2) -> false"); } public static void main(String argv[]){ Car c1 = new Car("ABC"); Car c2 = new Car("DEF"); Person p1 = new Person("Manel"); Person p2 = new Person("Manel"); foo(p1,p2); } }

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  • Java Annotations in eclipse Tooltip?

    - by reccles
    Is anyone aware of an eclipse plugin that updates the tooltip on hover over a method/class to include annotation information? There a few libraries we are using that have annotated methods and it would be handy if I could hover over the method and see what has been applied. I realize this would only work with annotations that have been retained but that is good enough.

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  • Java Scripting Engine importing my classes does not work

    - by Ayman
    A code is worth 1000 words of explaining it :-) package jasim; import javax.script.ScriptEngine; import javax.script.ScriptEngineManager; import javax.script.ScriptException; public class JSTest { public static void main(String[] args) throws ScriptException { ScriptEngine jse = new ScriptEngineManager().getEngineByExtension("js"); jse.eval("println(new jasim.JSTest().toString)"); } @Override public String toString() { return "JSTest Object"; } } This code will fail with the below exception: Exception in thread "main" javax.script.ScriptException: sun.org.mozilla.javascript.internal.EcmaError: ReferenceError: "jasim" is not defined. (<Unknown source>#1) in <Unknown source> at line number 1 How do I import my own classes into the ScriptEngine?

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  • Query by datetime in JDOQL / Java / GAE

    - by Jan Kuboschek
    I'm working on a GAE app. I want to query datastore and retrieve all records between startDate and endDate. Each record has a datetime field. I'm using a query similar to this (the below code is something I quickly grabbed - I'm not near my developer machine.): Query query = pm.newQuery(Employee.class); query.setFilter("lastName == lastNameParam"); query.setOrdering("hireDate desc"); query.declareParameters("String lastNameParam"); try { List results = (List) query.execute("Smith"); if (results.iterator().hasNext()) { for (Employee e : results) { // ... } } else { // ... no results ... } } finally { query.closeAll(); } How do I have to format the date to form a correctly working query? How is the datetime stamp stored in datastore? As timestamp? Fully formatted? I can't find ANY information on this. Please help.

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  • Java, Sychronize JTable and ResultSet

    - by rodion
    Hello, I have JTable, And AbstarctDataModel with fill(ResultSet rs) methods. How to correct synchronize cursor of JTable with ResultSet's cursor? Any links? Thanx a lat. P.S. Please, add AbstractTableModel tag -- Canton of Uri's citizen

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  • Cannot get right height of text in java.awt.BufferdImage/Graphics2D

    - by Tommy
    Im creating a servlet that renders a jpg/png with a given text. I want the text to be centered on the rendered image. I can get the width, but the height i'm getting seems to be wrong Font myfont = new Font(Font.SANS_SERIF, Font.BOLD, 400); BufferedImage image = new BufferedImage(500, 500, BufferedImage.TYPE_INT_ARGB); Graphics2D g = image.createGraphics(); g.setFont(myfont); g.setColor(Color.BLACK); FontMetrics fm = g.getFontMetrics(); Integer textwidth = fm.stringWidth(imagetext); Integer textheight = fm.getHeight(); FontRenderContext fr = g.getFontRenderContext(); LineMetrics lm = myfont.getLineMetrics("5", fr ); float ascent = lm.getAscent(); float descent = lm.getDescent(); float height = lm.getHeight(); g.drawString("5", ((imagewidth - textwidth) / 2) , y?); g.dispose(); ImageIO.write(image, "png", outputstream); These are the values I get: textwidth = 222 textheight = 504 ascent = 402 descent = 87 height = 503 Anyone know how to get the exact height om the "5" ? The estimated height should be around 250

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  • Symbol error in java application using netbeans 6.8 when adding a shared project to library

    - by Malachi
    I have a project which has shared functionality between three other projects and have linked these to existing projects as I normally would using the add project functionality of the libraries folder. This all used to work however when I started up Netbeans yesterday it just wasn't working as in the other projects won't compile even though the projects are linked. It can recognise the packages - just the actual classes themselves were not recognised... and to add to the weirdness some of the classes are getting picked up fine. I have checked the dist folder of the shared project and the Shared.jar file exists. Also I have checked the Jar and the other classes that are not being recognises are there also. Any suggestions? Solution I had to reinstall netbeans to get this solution resolved

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  • Java UTF-8 to ASCII conversion with supplements

    - by bozo
    Hi, we are accepting all sorts of national characters in UTF-8 string on the input, and we need to convert them to ASCII string on the output for some legacy use. (we don't accept Chinese and Japanese chars, only European languages) We have a small utility to get rid of all the diacritics: public static final String toBaseCharacters(final String sText) { if (sText == null || sText.length() == 0) return sText; final char[] chars = sText.toCharArray(); final int iSize = chars.length; final StringBuilder sb = new StringBuilder(iSize); for (int i = 0; i < iSize; i++) { String sLetter = new String(new char[] { chars[i] }); sLetter = Normalizer.normalize(sLetter, Normalizer.Form.NFC); try { byte[] bLetter = sLetter.getBytes("UTF-8"); sb.append((char) bLetter[0]); } catch (UnsupportedEncodingException e) { } } return sb.toString(); } The question is how to replace all the german sharp s (ß, Ð, d) and other characters that get through the above normalization method, with their supplements (in case of ß, supplement would probably be "ss" and in case od Ð supplement would be either "D" or "Dj"). Is there some simple way to do it, without million of .replaceAll() calls? So for example: Ðonardan = Djonardan, Blaß = Blass and so on. We can replace all "problematic" chars with empty space, but would like to avoid this to make the output as similar to the input as possible. Thank you for your answers, Bozo

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  • java BufferedReader specific length returns NUL characters

    - by Bastien
    I have a TCP socket client receiving messages (data) from a server. messages are of the type length (2 bytes) + data (length bytes), delimited by STX & ETX characters. I'm using a bufferedReader to retrieve the two first bytes, decode the length, then read again from the same bufferedReader the appropriate length and put the result in a char array. most of the time, I have no problem, but SOMETIMES (1 out of thousands of messages received), when attempting to read (length) bytes from the reader, I get only part of it, the rest of my array being filled with "NUL" characters. I imagine it's because the buffer has not yet been filled. char[] bufLen = new char[2]; _bufferedReader.read(bufLen); int len = decodeLength(bufLen); char[] _rawMsg = new char[len]; _bufferedReader.read(_rawMsg); return _rawMsg; I solved the problem in several iterative ways: first I tested the last char of my array: if it wasn't ETX I would read chars from the bufferedReader one by one until I would reach ETX, then start over my regular routine. the consequence is that I would basically DROP one message. then, in order to still retrieve that message, I would find the first occurence of the NUL char in my "truncated" message, read & store additional characters one at a time until I reached ETX, and append them to my "truncated" messages, confirming length is ok. it works also, but I'm really thinking there's something I could do better, like checking if the total number of characters I need are available in the buffer before reading it, but can't find the right way to do it... any idea / pointer ? thanks !

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  • some help required while working on java and cigwin together .

    - by Hippo
    Hello .. I am new to java and also cygwin . I do not have in detailed knowledge of both . I need some help.. I simple steps i will try to explain my problem. 1) I am working on tinyOS . its open source OS , used for wireless sensor networks. It provides java libraries to work on communication (PC to sensor) 2) I am working on windows xp environment through cigwin. 3) I am developing an application . THis application requires one java interface called "Serial Forwarder" , which is readily available in libraries provided. Previously i used to start this interface manually (by entering command *"java net.tinyos.sf.SerialForwarder ")*and then my application which uses this interface. But now i want to make my application independent . User need know about this background cygwin commands . 4) So in my java application i used "Runtime.getRuntime().exec( "java net.tinyos.sf.SerialForwarder)" . 5) This i neither giving any error nor starting the interface. Am I going on right way ? When i am using runtime execute command , how can i make sure that this command is called through cigwin interface ? Also .. if i want to write .bat file .. i which i can give commands which will be executed .. how can i make sure that those commands are given through cigwin .. and not through cmd.exe .. Please help . me .

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  • Are there any serialization frameworks for java

    - by Grofit
    I know there is simple, which seems to be a decent enough XML serializer and i know there is Jaxb which seems to do the job as well. However im after something a bit more generic, so I could serialize my model to Xml, Json, Binary etc. So the models are just dumb objects that just get thrown into some sort of serialization factory and then the relevant output is spat out... I dont see any reason why you couldn't do this with reflection, so for a REALLY simple solution get the relevent public properties, cut off the get or set and make that the element name... i.e getPersonName() would become <PersonName>xxxx</PersonName> or PersonName:XXXXX

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  • Using Java Reflections to retrieve member classes

    - by darkie15
    Hi All, I am using .getDeclaredClasses() method to retrieve all the classes that have been defined in object. However, I am not able to retrieve anonymous classes defined in the class. Here is the code sample that I am testing: public class TempCodes { public static void main(String[] args) { Ball b = new Ball() { public void hit() { System.out.println("You hit it!"); } }; b.hit(); } interface Ball { void hit(); } } and this is what my code does: memClass = className.getDeclaredClasses(); if (memClass .length > 0) { for (int index = 0 ; index < memClass .length ; index++) { System.out.println("\t\t\t" + memClass [index]); } } Can anyone help me understand how to retrieve the anonymous class? Regards, darkie

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  • MIDP Java implementation of SQLite DB

    - by Ram
    Are there any MIDP implementation of SQLite db available for use of sqlite db within a MIDlet, rather than using RMS. Of course, there are Floggy and OpenBaseMovil, however they are based on RMS, but are there any implementations that allows to perform operations in an sqlite db file?

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  • how to unescape XML in java

    - by Bas Hendriks
    Hi, I need to unescape a xml string containing escaped XML tags: &lt; &gt; &amp; etc... I did find some libs that can perform this task, but i'd rather use a single method that can perform this task. Can someone help? cheers, Bas Hendriks

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  • Multidimensional Array with different types in java

    - by Christian
    I want to store a data structure thats a table with one column Strings and another column of Ints. List<Entry<String, Integer>> li = new LinkedList<Entry<String, Integer>>(); would do the job for a list but I would rather have the performance of an array. I tried Entry<String, Integer>[] = new Entry<String, Integer>[10]; but that doesn't seem to work.

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  • Java: repetition, overuse -- problem?

    - by HH
    I try to be as minimalist as possible. Repetition is a problem. I hate it. When is it really a problem? what is static-overuse? what is field-method overuse? what is class-overuse? are there more types of overuse? Problem A: when it is too much to use of static? private static class Data { private static String fileContent; private static SizeSequence lineMap; private static File fileThing; private static char type; private static boolean binary; private static String name; private static String path; } private static class Print { //<1st LINE, LEFT_SIDE, 2nd LINE, RIGHT_SIDE> private Integer[] printPositions=new Integer[4]; private static String fingerPrint; private static String formatPrint; } Problem B: when it is too much to get field data with private methods? public Stack<Integer> getPositions(){return positions;} public Integer[] getPrintPositions(){return printPositions;} private Stack<String> getPrintViews(){return printViews;} private Stack<String> getPrintViewsPerFile(){return printViewsPerFile;} public String getPrintView(){return printView;} public String getFingerPrint(){return fingerPrint;} public String getFormatPrint(){return formatPrint;} public String getFileContent(){return fileContent;} public SizeSequence getLineMap(){return lineMap;} public File getFile(){return fileThing;} public boolean getBinary(){return binary;} public char getType(){return type;} public String getPath(){return path;} public FileObject getData(){return fObj;} public String getSearchTerm(){return searchTerm;} Related interface overuse overuse of static in a Game

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  • Changing volume in Java when using JLayer.

    - by Penchant
    I'm using JLayer to play an inputstream of mp3 data from the internet. How do i change the volume of the output? I'm using this code to play it: URL u = new URL(s); URLConnection conn = u.openConnection(); conn.setConnectTimeout(Searcher.timeoutms); conn.setReadTimeout(Searcher.timeoutms); bitstream = new Bitstream(conn.getInputStream()/*new FileInputStream(quick_file)*/); System.out.println(bitstream); decoder = new Decoder(); decoder.setEqualizer(equalizer); audio = FactoryRegistry.systemRegistry().createAudioDevice(); audio.open(decoder); for(int i = quick_positions[0]; i > 0; i--){ Header h = bitstream.readFrame(); if (h == null){ return; } bitstream.closeFrame();

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  • Java add leading zeros to a number....

    - by user69514
    I need to return a string in the form xxx-xxxx where xxx is a number and xxxx is another number, however when i have leading zeros they disappear. I'm trying number formatter, but it's not working. public String toString(){ NumberFormat nf3 = new DecimalFormat("#000"); NumberFormat nf4 = new DecimalFormat("#0000"); if( areaCode != 0) return nf3.format(areaCode) + "-" + nf3.format(exchangeCode) + "-" + nf4.format(number); else return exchangeCode + "-" + number; } } I figured it out: public String toString(){ NumberFormat nf3 = new DecimalFormat("000"); NumberFormat nf4 = new DecimalFormat("0000"); if( areaCode != 0) //myFormat.format(new Integer(someValue)); return nf3.format(new Integer(areaCode)) + "-" + nf3.format(new Integer(exchangeCode)) + "-" + nf4.format(new Integer(number)); else return nf3.format(new Integer(exchangeCode)) + "-" + nf4.format(new Integer(number)); }

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  • Java regex return after first match

    - by user216915
    hi how do i return after the first match of regular expression? (does the Matcher.find() method do that? ) say I have a string "abcdefgeee". I want to ask the regex engine stop finding immediately after it finds the first match of "e" for example. I am writing a method to return true/false if the pattern is found and i don't want to find the whole string for "e". (I am looking for a regex solution ) thanks

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  • Java JSTL / EL: nesting

    - by NoozNooz42
    I really don't know how to name this question, it's great if anyone with 2K+ rep can edit this title to better reflect my question (the fact that I can't name this easily is probably why I can't Google the solution). I've got this, which is working: <c:choose> <c:when test="${sometest}"> Hello, world! </c:when> <c:otherwise> <fmt:message key="${page.title}" /> </c:otherwise> </c:choose> And I want to change it to this: <c:choose> <c:when test="${sometest}"> <c:set var="somevar" scope="page" value="Hello, world!"/> </c:when> <c:otherwise> <c:set var="somevar" scope="page" value="<fmt:message key="${page.title}">" </c:otherwise> </c:choose But of course the following line ain't correct: <c:set var="somevar" scope="page" value="<fmt:message key="${page.title}">" How can I assign to the somevar variable the string resulting from a call?

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  • compact Number formatting behavior in Java (automatically switch between decimal and scientific notation)

    - by kostmo
    I am looking for a way to format a floating point number dynamically in either standard decimal format or scientific notation, depending on the value of the number. For moderate magnitudes, the number should be formatted as a decimal with trailing zeros suppressed. If the floating point number is equal to an integral value, the decimal point should also be suppressed. For extreme magnitudes (very small or very large), the number should be expressed in scientific notation. Alternately stated, if the number of characters in the expression as standard decimal notation exceeds a certain threshold, switch to scientific notation. I should have control over the maximum number of digits of precision, but I don't want trailing zeros appended to express the minimum precision; all trailing zeros should be suppressed. Basically, it should optimize for compactness and readability. 2.80000 - 2.8 765.000000 - 765 0.0073943162953 - 0.00739432 (limit digits of precision—to 6 in this case) 0.0000073943162953 - 7.39432E-6 (switch to scientific notation if the magnitude is small enough—less than 1E-5 in this case) 7394316295300000 - 7.39432E+6 (switch to scientific notation if the magnitude is large enough—for example, when greater than 1E+10) 0.0000073900000000 - 7.39E-6 (strip trailing zeros from significand in scientific notation) 0.000007299998344 - 7.3E-6 (rounding from the 6-digit precision limit causes this number to have trailing zeros which are stripped) Here's what I've found so far: The .toString() method of the Number class does most of what I want, except it doesn't upconvert to integer representation when possible, and it will not express large integral magnitudes in scientific notation. Also, I'm not sure how to adjust the precision. The "%G" format string to the String.format(...) function allows me to express numbers in scientific notation with adjustable precision, but does not strip trailing zeros. I'm wondering if there's already some library function out there that meets these criteria. I guess the only stumbling block for writing this myself is having to strip the trailing zeros from the significand in scientific notation produced by %G.

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  • Creating a java library

    - by Albinoswordfish
    This may be a silly question, but right now I have a rather large class that I want to use as a library. Where somebody can simply add this jar file to their classpath. And then simply do an import statement at the top, then he or she can start using this class. Is there anything special I need to do or can I simply just use the jar file built?

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  • Ignore certificate errors when requesting a URL in Java

    - by Ryan Elkins
    I'm trying to print a URL (without having a browser involved at all) but the URL is currently throwing the following: javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target I'm calling the URL using a JEditorPane's setPage method, which just takes a URL as a parameter. Assuming I can't change anything server side and I still need to get to this resource, how would I go about ignoring the certificate error (or something else that gets me to my goal)? Accessing this URL via a browser tells me the site is untrusted and asks me if I want to proceed.

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