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  • Java logger that automatically determines caller's class name

    - by alex
    public static Logger getLogger() { final Throwable t = new Throwable(); final StackTraceElement methodCaller = t.getStackTrace()[1]; final Logger logger = Logger.getLogger(methodCaller.getClassName()); logger.setLevel(ResourceManager.LOGLEVEL); return logger; } This method would return a logger that knows the class it's logging for. Any ideas against it?

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  • Java Runtime.freeMemory() returning bizarre results when adding more objects

    - by Sotirios Delimanolis
    For whatever reason, I wanted to see how many objects I could create and populate a LinkedList with. I used Runtime.getRuntime().freeMemory() to get the approximation of free memory in my JVM. I wrote this: public static void main(String[] arg) { Scanner kb = new Scanner(System.in); List<Long> mem = new LinkedList<Long>(); while (true) { System.out.println("Max memory: " + Runtime.getRuntime().maxMemory() + ". Available memory: " + Runtime.getRuntime().freeMemory() + " bytes. Press enter to use more."); String s = kb.nextLine(); if (s.equals("m")) for (int i = 0; i < 1000000; i++) { mem.add(new Long((new Random()).nextLong())); } } } If I write in m, the app adds a million Long objects to the list. You would think the more objects (to which we have references, so can't be gc'ed), the less free memory. Running the code: Max memory: 1897725952. Available memory: 127257696 bytes. m Max memory: 1897725952. Available memory: 108426520 bytes. m Max memory: 1897725952. Available memory: 139873296 bytes. m Max memory: 1897725952. Available memory: 210632232 bytes. m Max memory: 1897725952. Available memory: 137268792 bytes. m Max memory: 1897725952. Available memory: 239504784 bytes. m Max memory: 1897725952. Available memory: 169507792 bytes. m Max memory: 1897725952. Available memory: 259686128 bytes. m Max memory: 1897725952. Available memory: 189293488 bytes. m Max memory: 1897725952. Available memory: 387686544 bytes. The available memory fluctuates. How does this happen? Is the GC cleaning up other things (what other things are there on the heap to really clean up?), is the freeMemory() method returning an approximation that's way off? Am I missing something or am I crazy?

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  • JAVA: Build XML document using XPath expressions

    - by snoe
    I know this isn't really what XPath is for but if I have a HashMap of XPath expressions to values how would I go about building an XML document. I've found dom-4j's DocumentHelper.makeElement(branch, xpath) except it is incapable of creating attributes or indexing. Surely a library exists that can do this? Map xMap = new HashMap(); xMap.put("root/entity/@att", "fooattrib"); xMap.put("root/array[0]/ele/@att", "barattrib"); xMap.put("root/array[0]/ele", "barelement"); xMap.put("root/array[1]/ele", "zoobelement"); would result in: <root> <entity att="fooattrib"/> <array><ele att="barattrib">barelement</ele></array> <array><ele>zoobelement</ele></array> </root>

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  • How to synchronize java code

    - by Milan
    I have the next code: Process p = Runtime.getRuntime().exec(args); and I want my program to wait for the Runtime.getRuntime().exec(args); to finish cause it last 2-3sec and then to continue. Ideas?

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  • Regex help -- cleaning up whitespace -- Java

    - by FarmBoy
    I'm trying to view the text of HTML files in a reasonable way. After I remove all of the markup and retain only the visible text, I obtain a String that looks something like this: \n\n\n\n \n\n\n \n\n \n Title here \n\n\n \n\n \n\n Menu Item 1 \n\n \n\n Menu Item 2 \n\n\n \n\n you get the point. I would like to use String.replaceAll(String regex, String regex) to replace any whitespace substring that contains more than two occurances of \n with "\n\n". Any ideas?

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  • java applet communication port

    - by udhaya
    Communication ports: Change a given class in an applet in that way, that browser-defined proxy-configuration files can be used for applet communication with serve(upload method). i.e browser communicate via port 8080 or via ssl(443) - applet should also communicate by this port automatically. In the given method port 80 is hardcoded. -- please give some code or program for this..

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  • Java - How to get current year?

    - by Yatendra Goel
    I want to know the current Date and Time. The code Calendar.getInstance(); represents a date and time of the system on which the program is running and the system date can be wrong. So Is there any way by which I can get correct current date and time irrespective of the date and time of the system on which program is running?

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  • java.sql.SQLException: Parameter index out of range (3 > number of parameters, which is 2)

    - by sam
    @WebMethod(operationName = "SearchOR") public SearchOR getSearchOR (@WebParam(name = "comp") String comp, @WebParam(name = "name") String name) { //TODO write your implementation code here: SearchOR ack = null; try{ String simpleProc = "{ call getuser_info_or(?,?)}"; CallableStatement cs = con.prepareCall(simpleProc); cs.setString(1, comp); cs.setString(2, name); ResultSet rs = cs.executeQuery(); System.out.print("2"); /* int i = 0, j = 0; if (rs.last()) { i = rs.getRow(); ack = new SearchOR[i]; rs.beforeFirst(); }*/ while (rs.next()) { // ack[j] = new SearchOR(rs.getString(1), rs.getString(2)); // j++; ve.add(rs.getString(1)); ve.add(rs.getString(2)); }}catch ( Exception e) { e.printStackTrace(); System.out.print(e); } return ack; } I am getting error at portion i have made bold.It is pointing to that location.My Query is here: DELIMITER $$ DROP PROCEDURE IF EXISTS discoverdb.getuser_info_or$$ MySQL returned an empty result set (i.e. zero rows). CREATE PROCEDURE discoverdb.getuser_info_or ( IN comp VARCHAR(100), IN name VARCHAR(100), OUT Login VARCHAR(100), OUT email VARCHAR(100) ) BEGIN SELECT sLogin, sEmail INTO Login, email FROM ad_user WHERE company = comp OR sName=name; END $$ MySQL returned an empty result set (i.e. zero rows). DELIMITER ;

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  • Java Hibernate id auto increment

    - by vinise
    Hy I'v a little problem with hibernate on netbeans. I've a table with an Auto increment id : CREATE TABLE "DVD" ( "DVD_ID" INT not null primary key GENERATED ALWAYS AS IDENTITY (START WITH 1, INCREMENT BY 1), "TITLE" VARCHAR(150), "COM" LONG VARCHAR, "COVER" VARCHAR(150) ); But this auto increment is not properly detected with Reverse Engineering. I get a map file with this : <id name="dvdId" type="int"> <column name="DVD_ID" /> <generator class="assigned" /> </id> i've looked on google and on this site ... foud some stuf but i'm still stuck.. i've tried to add insert="false" update="false" on the map file but i get back : Caused by: org.xml.sax.SAXParseException: Attribute "insert" must be declared for element type "id". Anny help will be pleased Vincent

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  • How to solve following issue in java?

    - by lakshmi
    Im getting following error while running the query. org.hibernate.hql.ast.QuerySyntaxException: expecting CLOSE, found 'LIMIT' near line 1, column 194 [from com.claystone.db.Gpsdata where id.mobileunitid = '2090818044' and gpsdate in (select id.gpsdate from com.claystone.db.Gpsdata where id.mobileunitid = '2090818044' ORDER BY id.gpsdate DESC LIMIT 1 ) and gpsstatus='true'] This is my Query.Please give the suggession what is the mistake in this query? data=session.createQuery[from com.claystone.db.Gpsdata where id.mobileunitid = '2090818044' and gpsdate in (select id.gpsdate from com.claystone.db.Gpsdata where id.mobileunitid = '2090818044' ORDER BY id.gpsdate DESC LIMIT 1 ) and gpsstatus='true']

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  • java servlet:response.sendRedirect() not giving illegal state exception if called after commit of re

    - by sahil garg
    after commit of response as here redirect statement should give exception but it is not doing so if this redirect statemnet is in if block.but it does give exception in case it is out of if block.i have shown same statement(with marked stars ) at two places below.can u please tell me reason for it. protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub synchronized (noOfRequests) { noOfRequests++; } PrintWriter pw=null; response.setContentType("text/html"); response.setHeader("foo","bar"); //response is commited because of above statement pw=response.getWriter(); pw.print("hello : "+noOfRequests); //if i remove below statement this same statement is present in if block.so statement in if block should also give exception as this one do, but its not doing so.why? ***response.sendRedirect("http://localhost:8625/ServletPrc/login% 20page.html"); if(true) { //same statement as above ***response.sendRedirect("http://localhost:8625/ServletPrc/login%20page.html"); } else{ request.setAttribute("noOfReq", noOfRequests); request.setAttribute("name", new Name().getName()); request.setAttribute("GmailId",this.getServletConfig().getInitParameter("GmailId") ); request.setAttribute("YahooId",this.getServletConfig().getInitParameter("YahooId") ); RequestDispatcher view1=request.getRequestDispatcher("HomePage.jsp"); view1.forward(request, response); } }

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  • Timeout with GAE Java

    - by user242153
    Hi, I am having some issues with an app I have deployed on GAE. Specifically, I am intermittently running into the DeadlineExceededException where the server is not responding within the 30 seconds required. What is odd is that the code is not overly complex, it should run in milliseconds. My guess is that the delay is in dealing with the persistence manager and accessing the datastore. 2 questions: 1) What is the best way to track where all of the CPU time on the server is being used up? Log files do not seem helpful and to make things more complicated the code runs very fast when I am running it locally 2) Any tips / best practices in dealing with the 30 second exception? What are the biggest drivers of this? Datastore? HTTP requests / responses? Thanks

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  • NullPointerException Java help

    - by KP65
    Hello guys. I've been tearing my hair out the past few hours trying to solve this problem. Every time I click on a JButton which should open a JFrame(And it does), i get a stacktrace saying I have a null point exception at these bits of code: In class A i have: aButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { B instanceofB = new B(userSession.getBalance()); }); and Class B super.getSomeBtn().setVisible(false); This is where the stacktrace says the errors are in the two above sections. I have a line exactly the same as the one above in Class B and it works fine? Really stuck here!

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  • Searching a 2D array for a range of values in java

    - by Paige O
    I have a 2^n size int array and I want to check if an element exists that is greater than 0. If the element exists, I want to divide the array by 4 and check if the coordinates of the found element are in the 1st, 2nd, 3rd or 4th quadrant of the array. For example, logically if the element exists in the first quadrant it would look something like this: If array[][] 0 && the row of that coordinate is in the range 0-(grid.length/2-1) && the column of that coordinate is in the range 0-(grid.length/2-1) then do something. I'm really not sure how to check the row and column index of the found element and store those coordinates to use in my if statement. Help!

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  • Java HashMap with Int Array

    - by Sunil
    Hello I am using this code to check that array is present in the HashMap. public class Test { public static void main(String[]arg) { HashMap<int[],String> map= new HashMap<int[],String>(); map.put(new int[]{1,2}, "sun"); System.out.println(map.containsKey((new int[]{1,2}))); } } But this prints False. How can I check that array is present in the HashMap. Thanks in advance.

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