小编5Yr*_*DBA的帖子

我仍在尝试让JavaFX-samples-2.2.25 DataApp为我工作.我按照它的指示再次从头开始,并没有改变/添加任何东西.我得到以下glassfish服务器错误:

INFO:   EJB5181:Portable JNDI names for EJB CumulativeLiveSalesFacadeREST: [java:global/DataAppServer/CumulativeLiveSalesFacadeREST, java:global/DataAppServer/CumulativeLiveSalesFacadeREST!com.javafx.experiments.dataapp.server.service.CumulativeLiveSalesFacadeREST]
INFO:   EJB5181:Portable JNDI names for EJB RegionFacadeREST: [java:global/DataAppServer/RegionFacadeREST!com.javafx.experiments.dataapp.server.service.RegionFacadeREST, java:global/DataAppServer/RegionFacadeREST]
INFO:   EJB5181:Portable JNDI names for EJB LiveSalesListFacadeREST: [java:global/DataAppServer/LiveSalesListFacadeREST!com.javafx.experiments.dataapp.server.service.LiveSalesListFacadeREST, java:global/DataAppServer/LiveSalesListFacadeREST]
INFO:   WELD-000900 2.0.0 (SP1)
WARNING:   Class 'javax.ejb.PostActivate' not found, interception based on it is not enabled
WARNING:   Class 'javax.ejb.PrePassivate' not found, interception based on it is not enabled
INFO:   WebModule[null] ServletContext.log():Marking servlet ServletAdaptor as unavailable
SEVERE:   WebModule[/DataAppServer]Error loading WebappClassLoader (delegate=true; repositories=WEB-INF/classes/) com.sun.jersey.spi.container.servlet.ServletContainer
java.lang.ClassNotFoundException: com.sun.jersey.spi.container.servlet.ServletContainer
    at org.glassfish.web.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1761)
    at org.glassfish.web.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1611)
    at org.apache.catalina.core.StandardWrapper.loadServletClass(StandardWrapper.java:1533)
    at …

我定义了这样的地图:

private Map<Integer, MyTask> taskMap = new ConcurrentHashMap<Integer, MyTask>();

调用(taskMap为空)然后放置一个任务将返回null,并且由于下面的addedTask.getTaskNameId()调用,logger调用将抛出空指针异常.

MyTask addedTask = taskMap.put(task.getId(), task);
logger.logTask("added task", "TaskMgmtMgr::registerTask()", "added task=" + addedTask.getTaskNameId());

但是我可以在上面的记录器调用之后立即验证是否已成功使用这些语句:

private String getAvailableTaskListStr()
    {
        Collection<MyTask> tasks = taskMap.values();
        if (tasks.isEmpty())
        {
            return "No running task";
        }
        String nameList = "";
        int index = 0;
        for (MyTask task : tasks)
        {
            if (index == 0)
            {
                nameList += task;
            }
            else
            {
                nameList += ", task";
            }
            index++;
        }
        return "TotalTasks in TaskMap is " + …

第一次使用JTree.只是想知道是否可以拥有多个顶级TreeNodes？谢谢

我刚在VS2008中创建了一个ComboBox.我为它准备了四件物品,一件,两件,三件和四件.当我运行它时,默认情况下不显示任何内容.我需要选择一个来显示.如何在没有我选择的情况下默认显示第二项？我尝试在DisplayMember和ValueMeme属性中放一个数字,但它不起作用.

谢谢,

1. 在C++中,我们有值类型(int,long,float,...)和引用类型(class,struct,...).

2. 对于值类型,Array和Vector保存实际值;

3. 对于引用类型,Array和Vector仅保存对这些对象的引用;

4. 因此,当我们将引用类型放入Array和Vector时,我们需要确保这些对象存在足够长的时间(在整个过程中有效)以避免异常/错误;

我的上述陈述是否正确？如果我错了,请纠正我.

public class A { //some fields (may not only primitive types) and methods here}

   public class B {// some fields (may not only primitive types) and methods here, may also have a class A reference }

问题如下:

    public class Test{ 

public static void main(String[] args){ 

A a = new A();//1. it will allocate memory for one object of A and a is the reference points to that space? 

ArrayList<B> bList = new ArrayList<B>(10);//2. it will allocate memory for 10 objects …