java-programmer >>Problem about generics and class array

Problem about generics and class array

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- 2
  - Generic file name validation code?I need to validate a file name but it has to work on Windows & Unix!
    
    Does anybody know of java code that does this?
    
    thanks in advance
    
    harry
- 2
  - Ant : how can I use properties to store nested elementHi all,
    
    I have a build script which uses <fileset> nested in <path> to store
    the classpath and then this <path> is used in javac. e.g.
    
    <path id="MY_CLASSPATH">
    <fileset dir="${build.dir.lib}" includes="**/*.*"/>
    <fileset file="${global.lib.j2ee}"/>
    </path>
    
    <javac
    srcdir = "${project.compile.src}"
    destdir = "${project.compile.dest}">
    <classpath>
    <path refid="MY_CLASSPATH"/>
    </classpath>
    </javac>
    
    I just wondering is it possible to store the fileset in the properties
    file so that I can reference it in other place? I want to do a fileset
    instead of writing all the jar file names explicitly.
    e.g.
    In the properties file:
    project.compile.classpath=dir:${build.dir.lib}:file:${global.lib.j2ee}
    (or something like that....)
    
    then in my build.xml:
    <javac
    srcdir = "${project.compile.src}"
    destdir = "${project.compile.dest}">
    classpath = "${project.compile.classpath}">
    </javac>
- 2
  - reading \n from a fileI am reading from a file and storing in String.
    
    I need to separate a word so that part of it goes to next line
    
    abc\nxyd
    
    I am moving this text to button.setText() and this should
    appear on the button as
    
    abc
    xyz
    
    for that I am putting newline escape there.
    
    it is not working. I have tried putting unicode string in
    place of \n that also is not working.
    
    how to do it?
    
    -Rawat
- 3
  - Java Window/GUI HelpOk im trying to create a program in java right now and my knowledge of
    it has proved somewhat .... limited.....
    
    Info:
    Im making a program using javaspaces to simulate an auction over the
    network.
    Requirements:
    1) user can add a lot to the auction
    2) browse current lots on sale
    3) users can withdraw their item from sale.
    
    OK now this has to be done as a GUI which is what is hindering me.
    The only type of GUI work i have done have been fairly static.
    Just a plain window with a few buttons and such which might bring up a
    picture or change some text in a text box or something.
    
    But what im having trouble with now is the whole GUI design and how to
    go about it.
    
    Say i had 3 butons in my window |Add| |Browse| |withdraw|.
    Clicking any of these should change the whole structure of the window
    and i dont know how to do this..
    Itd be a case of clearing half of the window off and redrawing over
    the top of it.
    Unless i went the route of having an extremely simple window with 3
    buttons, clicking each would open up a new window with the desired
    options...
    
    What would be the best way to go about it? and how would i go about
    implementing it? just a few tips are needed :)
    
    Im really not a windows fan... a console app would take an hour or so.
    This is gonna keep me going for aaaaaages :$
    
    I hope im making sense and not babbing too much - 36 hours without
    sleep and a huge abundance of caffeine is warping my mind o.O
- 8
  - CachedRowSet and double column typesHi, there,
    
    I have a CachedRowSet obtained from Sun's CachedRowSetImpl and I'm
    trying to use it with a MySql database. I have a table test that has
    the basic column types. If I use a plain double column type and I have
    to update a row with the double field having the fraction part
    something like 1/3 (i.e. 0.3333....), then the acceptChanges fails with
    the error
    javax.sql.rowset.spi.SyncProviderException: 1 conflicts while
    synchronizing
    If I have a double(12,2) column type or the like (i.e. I limit the
    precision) or if I have a fixed fraction part (something like 0.5,
    let's say), then acceptChanges works fine.
    I havent logged the sqls generated by the acceptChanges of the
    CachedRowSetImpl, but I remember encountering something similar on some
    different software components and what was happening in that case (and
    I suppose it's happen in this case too) is that the sqls generated were
    trying to find the original row using all the fields in the row and not
    only the primary key, as it should be the case, i.e. there was
    something like :
    update test set f1=x1, f2=x2, f3=x3 where f1=y1 and f2=y2 and f3=y3
    Now, since there's that "unlimited" number of digits after the decimal
    point, it wouldnt have found the original record (maybe because there
    was a different number of digits used to represent the same number on
    the MySql server and on the MySql client).
    
    My question - is there a way to tell CachedRowSet how the row
    identification should be done (to say what goes into the "where"
    clause)? Eventually is there a smarter, free implementation of
    CachedRowSet ?
    
    Thanks, Don
    
    PS. See used code and table data bellow.
    
    ---------------------------------
    
    package dbtools;
    
    import com.sun.rowset.CachedRowSetImpl;
    import javax.sql.rowset.CachedRowSet;
    import org.apache.commons.logging.Log;
    import org.apache.commons.logging.LogFactory;
    import java.util.*;
    import java.sql.*;
    
    public class CacheRecSet {
    
    Connection connection = null;
    Random rand = new Random();
    private Log log = LogFactory.getLog(this.getClass());
    
    /** Creates a new instance of CacheRecSet */
    public CacheRecSet() {
    }
    
    protected void setUp() {
    if (connection != null) {
    return;
    }
    
    /*
    // MySql through OBDC
    String uri =
    "jdbc:odbc:mysqlodbcdbstorage;UID=tintin;PWD=tintin";
    
    log.info("Initializing connection from '" + uri + "'");
    
    try {
    // Load the JDBC-ODBC bridge driver
    Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
    } catch (ClassNotFoundException e) {
    log.error("Opening connection",e);
    return;
    }
    
    try {
    connection = DriverManager.getConnection(uri);
    log.info(" Loaded connection from '" + uri + "'");
    } catch (Exception e) {
    log.error("ERROR Opening connection");
    return;
    }
    */
    
    // MySql direct
    String uri =
    "jdbc:mysql://localhost:3306/dbstorage?user=tintin&password=tintin";
    
    log.info("Initializing connection from '" + uri + "'");
    
    try {
    // Load the driver
    Class.forName("org.gjt.mm.mysql.Driver");
    } catch (ClassNotFoundException e) {
    log.error("Opening connection", e);
    }
    // add support for connection pooling
    // Class.forName("org.apache.commons.dbcp.PoolingDriver");
    
    try {
    connection = DriverManager.getConnection(uri);
    log.info(" Loaded connection from '" + uri + "'");
    } catch (Exception e) {
    log.error("Opening connection",e);
    }
    
    /*
    // PostgreSql direct
    String uri =
    "jdbc:postgresql://localhost:5432/dbstorage?user=tintin&password=tintin";
    
    log.info("Initializing connection from '" + uri + "'");
    
    try {
    // Load the driver
    Class.forName("org.postgresql.Driver");
    } catch (ClassNotFoundException e) {
    log.error("Opening connection", e);
    }
    
    try {
    connection = DriverManager.getConnection(uri);
    log.info(" Loaded connection from '" + uri + "'");
    } catch (Exception e) {
    log.error("Opening connection", e);
    }
    */
    }
    
    protected void tearDown() {
    if (connection != null) {
    try {
    connection.close();
    } catch (Exception e) {
    log.error("Closing connection");
    }
    }
    
    connection = null;
    
    }
    
    public void testMulti() {
    if (connection == null) {
    log.error("testMulti - null connection");
    }
    
    log.info("testMulti");
    
    CachedRowSet crset;
    
    try {
    java.sql.Statement stmt = connection.createStatement();
    ResultSet rs = stmt.executeQuery("SELECT * FROM test where
    RecId = 1"); // for postgresql it doesnt work like this
    //ResultSet rs = stmt.executeQuery("SELECT * FROM test
    where "RecId" = 1"); // for postgresql it works like this
    
    crset = new CachedRowSetImpl();
    crset.populate(rs);
    
    log.info("SIZE = "+crset.size());
    if (crset.size() > 0) {
    crset.first();
    
    double fract = (double)1 / 3;
    //fract = fract/3;
    double dbl = (rand.nextInt(50)*1000) + fract;
    java.util.Date dt = new java.util.Date();
    java.sql.Date dt2 = new java.sql.Date(dt.getTime());
    
    crset.updateInt("Married", 0); // int field (wanted as
    bool...)
    crset.updateString("Name", "coco"); // varchar field
    crset.updateDouble("Salary", dbl); // double fld
    crset.updateDate("DtCreate", dt2); // date field
    String comments = "a test "+dt.toString() + " ===> " +
    rand.nextInt(50);
    crset.updateString("Comments", comments); // blob field
    crset.updateInt("Age", rand.nextInt(50)); // int field
    
    //int [] keys = {1};
    //crset.setKeyColumns(keys);
    
    //crset.setTableName("test"); // when dealing
    PostGreSql, needed to be added as it seems...
    
    crset.updateRow();
    crset.acceptChanges(connection);
    }
    
    rs.close();
    
    } catch (Exception e) {
    log.error("testMulti",e);
    return;
    }
    
    log.info("...OK");
    }
    
    public static void main(String args[]) {
    CacheRecSet instance = new CacheRecSet();
    
    instance.setUp();
    instance.testMulti();
    instance.tearDown();
    }
    
    }
    
    -----------------------------------
    
    CREATE DATABASE IF NOT EXISTS dbstorage;
    USE dbstorage;
    
    DROP TABLE IF EXISTS `test`;
    CREATE TABLE `test` (
    `RecID` int(10) unsigned NOT NULL auto_increment,
    `Married` int(11) default NULL,
    `Name` varchar(200) default NULL,
    `Salary` double(10,2) default NULL,
    `DtCreate` date default NULL,
    `Comments` text,
    `Age` int(10) unsigned default NULL,
    PRIMARY KEY (`RecID`)
    ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
    
    /*!40000 ALTER TABLE `test` DISABLE KEYS */;
    INSERT INTO `test`
    (`RecID`,`Married`,`Name`,`Salary`,`DtCreate`,`Comments`,`Age`) VALUES
    (1,0,'coco',15000.33,'2006-12-24','a test Sun Dec 24 00:20:09 EST 2006
    ===> 25',22),
    (2,1,'0',NULL,NULL,NULL,NULL),
    (3,NULL,'silviu',NULL,NULL,NULL,12);
    /*!40000 ALTER TABLE `test` ENABLE KEYS */;
- 9
  - HTTPConnection - verbose error messagesI have a java application that polls an asp page for the purpose of
    inserting to a data base. I am interested in seeing verbose (ie
    unfriendly HTTP error messages) when there is an internal server error
    (code 500). Below is the code snippet that makes the application's web
    connection and captures the response messages.
    
    String user = "";
    //String user = "Someone";
    
    try{//create url object
    urlWithQueryString =
    "http://www.someaddress.com/lpt/lpt_login.asp?User=" + user +
    "&FName=Alonzo&LName=Garbonzo&timeStamp=20060110_1106";
    System.err.println("urlWithQueryString ln 35: " +
    urlWithQueryString);
    url = new URL(urlWithQueryString);
    }catch(MalformedURLException mURLE){
    System.err.println( "MalformedURLException thrown in WriteToWebDB: ln
    41 " + mURLE.getMessage() );
    System.err.println("");
    return NetworkStatus.NETWORK_CONNECTION_PROBLEM;
    }
    
    try{//open connection. Write data succeeds or fails here
    connection = (HttpURLConnection)url.openConnection();
    inputStream = connection.getInputStream();
    connection.setInstanceFollowRedirects(true);
    }catch(IOException iOE1){
    try{
    System.err.println( "IOException caught in WriteToWebDB: ln 52");
    System.err.println("Connection response code ln 53: " +
    connection.getResponseCode());
    System.err.println("Connection message ln 54: " +
    connection.getResponseMessage());
    System.err.println("Exception message ln 55: " + iOE1.getMessage());
    }catch(IOException iOE){System.err.println("IOException caught ln 56"
    + iOE.getMessage());}
    return NetworkStatus.NETWORK_CONNECTION_PROBLEM;
    }
    
    ********************************************
    
    Below are three examples of server output - the first two have
    defective connection strings to force server error and one is a good
    connection string that inserts to the data base. Note that defective
    string passed from the application returns an error message without
    much information while the defective string passed from a browser
    returns a verbose and detailed error message. Can anyone help in
    discovering a way to recover verbose detailed error messages in the
    java application? Any help is greatly appreciated.
    
    Guy Sussman
    
    ********************************************
    
    Web server output to application connection when String user = ""
    
    urlWithQueryString ln 35:
    http://www.guysussman.com/lpt/lpt_login.asp?User=&FName=Alonzo&LName=Garbonzo&timeStamp=20060110_1106
    IOException caught in WriteToWebDB: ln 52
    Connection response code ln 53: 500
    Connection message ln 54: Internal Server Error
    Exception message ln 55: Server returned HTTP response code: 500 for
    URL:
    http://www.guysussman.com/lpt/lpt_login.asp?User=&FName=Alonzo&LName=Garbonzo&timeStamp=20060110_1106
    
    ********************************************
    
    Web server output to browser connection when String user = ""
    
    Microsoft OLE DB Provider for ODBC Drivers error '80004005'
    [Microsoft][ODBC Microsoft Access Driver] Field 'tbl_test.Usr' cannot
    be a zero-length string.
    /lpt/lpt_login.asp, line 25
    
    ********************************************
    
    Web server output to application connection when String user =
    "Someone"
    
    urlWithQueryString ln 35:
    http://www.guysussman.com/lpt/lpt_login.asp?User=Someone&FName=Alonzo&LName=Garbonzo&timeStamp=20060110_1106
    Http connection status (WriteToWebDB ln.69): OK ResponseCode = 200
    
    ********************************************
- 12
  - JAXB & Excel 2003I downloaded Microsoft Office 2003 Reference Schemas from:
    
    http://www.microsoft.com/downloads/details.aspx?familyid=fe118952-3547-420a-a412-00a2662442d9&displaylang=en
    
    Then I tried to use JAXB on them, specifically excel.xsd and
    excelss.xsd. The first one passes OK, but doesn't contain Worksheet
    element, which is the root element for Excel 2003 documents saved as
    XML. The other schema, excelss.xsd, contains the definition of this
    element, but doesn't pass through JAXB. The output of:
    
    xjc -p generated excelss.xsd
    
    is:
    
    -------------------- cut here ---------------
    parsing a schema...
    [ERROR] Property "Name" is already defined.
    line 219 of file:/C:/xls/office.xsd
    
    [ERROR] The following location is relevant to the above error
    line 204 of file:/C:/xls/office.xsd
    
    [ERROR] Property "Namespaceuri" is already defined.
    line 214 of file:/C:/xls/office.xsd
    
    [ERROR] The following location is relevant to the above error
    line 199 of file:/C:/xls/office.xsd
    
    [ERROR] Property "Url" is already defined.
    line 224 of file:/C:/xls/office.xsd
    
    [ERROR] The following location is relevant to the above error
    line 209 of file:/C:/xls/office.xsd
    
    [ERROR] Property "FullColumns" is already defined.
    line 590 of file:/C:/xls/excelss.xsd
    
    [ERROR] The following location is relevant to the above error
    line 5042 of file:/C:/xls/excel.xsd
    
    [ERROR] Property "FullRows" is already defined.
    line 595 of file:/C:/xls/excelss.xsd
    
    [ERROR] The following location is relevant to the above error
    line 5047 of file:/C:/xls/excel.xsd
    
    [ERROR] Property "DefaultColumnWidth" is already defined.
    line 555 of file:/C:/xls/excelss.xsd
    
    [ERROR] The following location is relevant to the above error
    line 5057 of file:/C:/xls/excel.xsd
    
    [ERROR] Property "DefaultRowHeight" is already defined.
    line 560 of file:/C:/xls/excelss.xsd
    
    [ERROR] The following location is relevant to the above error
    line 5052 of file:/C:/xls/excel.xsd
    
    [ERROR] Property "Fill" is already defined.
    line 374 of file:/C:/xls/office.xsd
    
    [ERROR] The following location is relevant to the above error
    line 405 of file:/C:/xls/office.xsd
    
    [ERROR] Property "Colors" is already defined.
    line 422 of file:/C:/xls/office.xsd
    
    [ERROR] The following location is relevant to the above error
    line 429 of file:/C:/xls/office.xsd
    
    [ERROR] Property "Path" is already defined.
    line 597 of file:/C:/xls/vml.xsd
    
    [ERROR] The following location is relevant to the above error
    line 616 of file:/C:/xls/vml.xsd
    
    [ERROR] Property "Opacity2" is already defined.
    line 288 of file:/C:/xls/vml.xsd
    
    [ERROR] The following location is relevant to the above error
    line 316 of file:/C:/xls/vml.xsd
    
    [ERROR] Property "Title" is already defined.
    line 292 of file:/C:/xls/vml.xsd
    
    [ERROR] The following location is relevant to the above error
    line 314 of file:/C:/xls/vml.xsd
    
    [ERROR] Property "Path" is already defined.
    line 745 of file:/C:/xls/vml.xsd
    
    [ERROR] The following location is relevant to the above error
    line 771 of file:/C:/xls/vml.xsd
    
    [ERROR] Property "Path" is already defined.
    line 531 of file:/C:/xls/vml.xsd
    
    [ERROR] The following location is relevant to the above error
    line 551 of file:/C:/xls/vml.xsd
    
    [ERROR] Property "Wrapcoords" is already defined.
    line 44 of file:/C:/xls/vml.xsd
    
    [ERROR] The following location is relevant to the above error
    line 46 of file:/C:/xls/vml.xsd
    
    [ERROR] Property "Path" is already defined.
    line 647 of file:/C:/xls/vml.xsd
    
    [ERROR] The following location is relevant to the above error
    line 663 of file:/C:/xls/vml.xsd
    
    [ERROR] Property "Spid" is already defined.
    line 664 of file:/C:/xls/vml.xsd
    
    [ERROR] The following location is relevant to the above error
    line 666 of file:/C:/xls/vml.xsd
    
    [ERROR] Property "Path" is already defined.
    line 681 of file:/C:/xls/vml.xsd
    
    [ERROR] The following location is relevant to the above error
    line 701 of file:/C:/xls/vml.xsd
    
    [ERROR] Property "Path" is already defined.
    line 623 of file:/C:/xls/vml.xsd
    
    [ERROR] The following location is relevant to the above error
    line 640 of file:/C:/xls/vml.xsd
    
    [ERROR] Property "Path" is already defined.
    line 569 of file:/C:/xls/vml.xsd
    
    [ERROR] The following location is relevant to the above error
    line 590 of file:/C:/xls/vml.xsd
    
    [ERROR] Property "Fill" is already defined.
    line 198 of file:/C:/xls/vml.xsd
    
    [ERROR] The following location is relevant to the above error
    line 207 of file:/C:/xls/vml.xsd
    
    [ERROR] Property "Path" is already defined.
    line 711 of file:/C:/xls/vml.xsd
    
    [ERROR] The following location is relevant to the above error
    line 729 of file:/C:/xls/vml.xsd
    
    Failed to parse a schema.
    -------------------- cut here ---------------
    
    Any ideas?
- 12
  - Newbie Question: Eclipse RCP - three questionsHi all,
    
    I'm trying to develop Eclipse RCP database based application and I've faced
    following problems.
    
    First :
    I don't know where can I create and dispose the ImageRegistry ?
    Class WorkbenchAdvisor doesn't seem to be right place to do this, I couldn't
    find the method
    like initializeImageRegistry.
    
    Second:
    Where should I keep for example the database connections or references to
    the beans
    shared among different parts of the application especially further plugins ?
    
    Third:
    Is there any example of the real database driven RCP application with source
    code available
    or at least an article describing this topic ?
    
    Thank's in advance
    
    --
    Marcin Misiewicz
- 12
  - Preparing a StringHello
    I am preparing xpath queries for xml parsing.
    
    To make each xpath query i have to add variables and join more Strings.
    I was wondering if there is any way i can create java string same as
    SqlPrepareStatement
    somthing like
    String p = "my name is ?"
    
    public void foo("joe"){
    //add name in string p so that
    //p = "my name is joe"
    }
    
    any help
    thanks
    Pinto
- 14
  - need Java book for a C# / C C++ proficient programmer?hi,
    
    I've never cared for Java before but now i feel like learning it. I'm
    an MCP and a pretty experienced programmer. Also, i plan to take the
    SCJP and maybe the SCMAD exams.
    
    Is there a java book out that is for a programmer?? I already have a
    copy of Hebert S. java reference, that would be my last option. Also,
    i would want the books to somewhat cover the exams I plan to do.
    
    Thanks so much
    Gideon
- 14
  - linux-jdk 1.6.0 ("mustang")Hello!
    
    I would like to know if somebody had good experience running jdk 1.6.0
    "mustang" on 6.0?
    
    P.S. Sorry for short question 8)
    
    --
    NEVE-RIPE, will build world for food
    Ukrainian FreeBSD User Group
    http://uafug.org.ua/
- 14
  - Add pps or flash or dat to java app.Do any one knows how 2 add pps or flash or video to java application?If
    u know plz sent me a sample sourse code to my mail with needed
    libraries.
    <email***@***.com>
- 14
  - IE7 BetaI can not get JAVA to run in IE7 Beta. Actually, it didn't run under IE6
    either. I've exhausted my limited knowledge already. Any advice? Links?
- 14
  - Printing questionsHello!
    
    I'm trying to develop an application to print PDF files, using JPedal.
    Two questions:
    
    1) I'd like users can specify printing properties, like size,
    margins... following an example on JPedal site I tryed:
    
    // new attribute set
    PrintRequestAttributeSet aset = new HashPrintRequestAttributeSet();
    
    // dialog
    printJob.printDialog(aset);
    
    // read dialog properties
    PageRanges r = (PageRanges)aset.get(PageRanges.class);
    PageFormat pf = (PageFormat)aset.get(PageFormat.class);
    
    but it doesn't work... :(
    Is there a way to set those parameters via code? I need to set margins
    to 0,0,0,0...
    
    2) I'd like to improve the quality of printed docs... I think it uses
    a very low quality to render my PDF (like 72dpi or so), is there a way
    to increase dpi? In a PDFProducer for TFax I was able to do that
    passing a bigger BufferedImage to Jpedal, is there a way to do the
    same thing here (without redifining the print() method)?
    Thanks!
- 16
  - negative dns caching problem *resolved* (was Re: JDK 1.5.0 patchsetAfter months of fighting with this, today I stumbled upon the answer. It
    was a java command line test case that led me to it.
    
    >From the command line, FreeBSD's JDK does -exactly- what it is supposed to
    with negative caching. My test case involved restarting BIND, adding a
    firewall rule for a host's name servers, having Java try to resolve the
    name (and of course fail), having Java wait while removing the firewall
    rule and having Java try again to resolve the name. All the while I was
    watching network traffic with tcpdump.
    
    Exactly as it is supposed to, the JDK tried again and succeeded after I
    removed the firewall rule.
    
    So this meant that it had to be something to do with Tomcat or
    commons-daemon/jsvc.
    
    On a whim, I removed the entry for Tomcat's native libraries, and it
    started to work correctly.
    
    Then I did an ldd against libtcnative, and found that I had compiled it
    with gcc 4.2.1. Knowing that there are problems with gcc 4.2, I
    recompiled with gcc 3.4.6. It continues to work correctly.
    
    So this turned out to be a multi-pronged problem. Earlier I was building
    a version of the JDK that somehow never read java.security, and that
    required wiping out the work directory entirely and bootstrapping off the
    Diablo JDK. Then, something about compiling the Tomcat native libraries
    with gcc 4.2.1 was apparently creating this bad behaviour situation.
    
    So if you're using Tomcat, and you want to use the Tomcat native
    libraries, do not compile them with gcc 4.2. In fact, you probably will
    want to make sure you compile them with the same major.minor version of
    gcc you used to compile libapr just to be safe. The Tomcat native library
    IS capable of screwing your DNS resolution.
    
    Nick
    
    On Sun, 28 Oct 2007, Nick Johnson wrote:
    
    > Sadly, this does NOT correct the eternal negative caching problem. That
    > problem still remains, even though I've configured the JDK not to cache
    > negative results at all.
    >
    > I can do a tcpdump and see that the JDK makes no attempt whatsoever to
    > query a host again after it has previously timed out. Nothing I've tried
    > to fix the problem has had any effect.
    >
    > Nick
    >
    > On Fri, 26 Oct 2007, Nick Johnson wrote:
    >
    > > It remains to be seen whether this will resolve the problems I've been
    > > having with InetAddress caching, but I am hopeful that it will.
    >
    >
    
    --
    "Courage isn't just a matter of not being frightened, you know. It's being
    afraid and doing what you have to do anyway."
    Doctor Who - Planet of the Daleks
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Message

Kaiser S.

Posted: 2007-5-3 20:29:00

Top

java-programmer, Problem about generics and class array Can somebody explains why the last line of code doesn't compile ?

public class TestClassArray {
private static class A {
}
private static class B extends A {
}

Class[] rawClasses = { B.class }; // warning

Class<?>[] wildcardsClasses = { B.class };

// error : Cannot create a generic array of Class<? extends
TestClassArray.A>
Class<? extends A>[] upperBoundClasses = { B.class };
}

Ingo R. Homann

Posted: 2007-5-3 21:20:00

Top

java-programmer >> Problem about generics and class array Hi usual suspect, ;-)

Kaiser S. wrote:
> Can somebody explains why the last line of code doesn't compile ?
>
> Class<? extends A>[] upperBoundClasses = { B.class };

Because Generic Arrays are not allowed. (Read the fine error message ;-)

Ciao,
Ingo

Kaiser S.

Posted: 2007-5-3 21:43:00

Top

java-programmer >> Problem about generics and class array >> Can somebody explains why the last line of code doesn't compile ?
>>
>> Class<? extends A>[] upperBoundClasses = { B.class };
>
> Because Generic Arrays are not allowed. (Read the fine error message ;-)

Damned! Thx for your help :)

Ingo R. Homann

Posted: 2007-5-3 21:48:00

Top

java-programmer >> Problem about generics and class array Hi, Mr. Spacey ;-)

Kaiser S. wrote:
>>> Can somebody explains why the last line of code doesn't compile ?
>>>
>>> Class<? extends A>[] upperBoundClasses = { B.class };
>>
>> Because Generic Arrays are not allowed. (Read the fine error message ;-)
>
> Damned! Thx for your help :)

Note that a

List<Class<? extends A>>

is perfectly OK!

Ciao,
Ingo

Index ‹ java-programmer

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