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callAction giving nullPointerException

General questions regarding the development with JVx.

callAction giving nullPointerException

Postby lucdep » Wed Nov 06, 2019 11:12 am

Hi,

I have following code in my Session

Code: Select all
public DBStorage getVUserSession() throws Exception
   {
      DBStorage dbsVUserSession = (DBStorage)get("vUserSession");
      if (dbsVUserSession == null)
      {
         dbsVUserSession = new DBStorage();
         dbsVUserSession.setWritebackTable("v_user_grup_admi");
         dbsVUserSession.setDBAccess(getDBAccess());
         dbsVUserSession.open();
         put("vUserSession", dbsVUserSession);
      }
      return dbsVUserSession;
   }

public Object getUserEmplName() throws Exception
   {
      DBStorage dbVU = getVUserSession();
      ICondition pFilter = new Equals("USERNAME", TriggerAPI.getCurrentUserName());
      
      IBean rowUserLogin = new Bean();
      rowUserLogin = dbVU.fetchBean(pFilter);
         
      return rowUserLogin.get("EMPL_NAME");
   }


but when I call the method getUserEmplName from a workscreen with

Code: Select all
public void onActivate() throws Throwable
   {
      labelUser.setText(getConnection().callAction("getUserEmplName").toString());
   }


I am getting a NullPointerException

Code: Select all
java.lang.NullPointerException
   at be.moonfox.apps.max.Session.getUserEmplName(Session.java:250)
   at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
   at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
   at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
   at java.base/java.lang.reflect.Method.invoke(Method.java:567)
   at com.sibvisions.util.Reflective.call(Reflective.java:290)
   at com.sibvisions.rad.server.GenericBean.invoke(GenericBean.java:808)
   at com.sibvisions.rad.server.GenericBean.invoke(GenericBean.java:722)
   at com.sibvisions.rad.server.GenericBean.invoke(GenericBean.java:777)
   at com.sibvisions.rad.server.DefaultObjectProvider.invoke(DefaultObjectProvider.java:430)
   at com.sibvisions.visionx.server.VisionXObjectProvider.invoke(Unknown Source)
   at be.moonfox.apps.max.screens.ProductDesign.<null>.getUserEmplName(Unknown Source)
   at com.sibvisions.rad.server.AbstractSession.executeWithSessionContext(AbstractSession.java:770)
   at com.sibvisions.rad.server.AbstractSession.executeIntern(AbstractSession.java:722)
   at com.sibvisions.rad.server.AbstractSession.execute(AbstractSession.java:690)
   at com.sibvisions.rad.server.Server.executeIntern(Server.java:2355)
   at com.sibvisions.rad.server.Server.execute(Server.java:660)
   at com.sibvisions.rad.server.DirectServerConnection.call(DirectServerConnection.java:305)
   at javax.rad.remote.AbstractConnection.callAction(AbstractConnection.java:757)
   at be.moonfox.apps.max.screens.ProductDesignWorkScreen.onActivate(ProductDesignWorkScreen.java:127)
   at com.sibvisions.apps.projx.screens.DataSourceWorkScreen.activate(DataSourceWorkScreen.java:607)
   at com.sibvisions.apps.projx.screens.DataSourceWorkScreen.notifyVisible(DataSourceWorkScreen.java:372)
   at com.sibvisions.apps.projx.ProjX.openContainer(ProjX.java:3505)
   at com.sibvisions.apps.projx.ProjX.openWorkScreen(ProjX.java:2339)
   at com.sibvisions.apps.projx.ProjX.openWorkScreen(ProjX.java:899)
   at javax.rad.application.genui.RemoteWorkScreenApplication.openWorkScreen(RemoteWorkScreenApplication.java:82)
   at com.sibvisions.apps.projx.ProjX.doOpenWorkScreen(ProjX.java:6968)
   at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
   at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
   at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
   at java.base/java.lang.reflect.Method.invoke(Method.java:567)
   at javax.rad.util.EventHandler$ListenerHandler.dispatchEvent(EventHandler.java:1042)
   at javax.rad.util.EventHandler.dispatchEvent(EventHandler.java:608)
   at javax.rad.util.RuntimeEventHandler.dispatchEvent(RuntimeEventHandler.java:73)
   at com.sibvisions.rad.ui.swing.impl.component.SwingAbstractButton.actionPerformed(SwingAbstractButton.java:396)
   at java.desktop/javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1967)
   at java.desktop/javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2308)
   at java.desktop/javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:405)
   at java.desktop/javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:262)
   at java.desktop/javax.swing.AbstractButton.doClick(AbstractButton.java:369)
   at java.desktop/javax.swing.plaf.basic.BasicMenuItemUI.doClick(BasicMenuItemUI.java:1020)
   at java.desktop/javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(BasicMenuItemUI.java:1064)
   at java.desktop/java.awt.Component.processMouseEvent(Component.java:6632)
   at java.desktop/javax.swing.JComponent.processMouseEvent(JComponent.java:3342)
   at java.desktop/java.awt.Component.processEvent(Component.java:6397)
   at java.desktop/java.awt.Container.processEvent(Container.java:2263)
   at java.desktop/java.awt.Component.dispatchEventImpl(Component.java:5008)
   at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2321)
   at java.desktop/java.awt.Component.dispatchEvent(Component.java:4840)
   at java.desktop/java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4918)
   at java.desktop/java.awt.LightweightDispatcher.processMouseEvent(Container.java:4547)
   at java.desktop/java.awt.LightweightDispatcher.dispatchEvent(Container.java:4488)
   at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2307)
   at java.desktop/java.awt.Window.dispatchEventImpl(Window.java:2762)
   at java.desktop/java.awt.Component.dispatchEvent(Component.java:4840)
   at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:772)
   at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:721)
   at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:715)
   at java.base/java.security.AccessController.doPrivileged(AccessController.java:389)
   at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:85)
   at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:95)
   at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:745)
   at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:743)
   at java.base/java.security.AccessController.doPrivileged(AccessController.java:389)
   at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:85)
   at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:742)
   at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203)
   at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124)
   at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113)
   at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109)
   at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
   at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90)



Any idea where this goes wrong?


Luc
lucdep
 
Posts: 52
Joined: Wed Oct 10, 2018 12:01 pm

Re: callAction giving nullPointerException

Postby johnit » Wed Nov 06, 2019 12:11 pm

I'm not sure if someone here can help you with debugging your code? Your question is not JVx specific and more a general development question?

The line number:
Code: Select all
at be.moonfox.apps.max.Session.getUserEmplName(Session.java:250)

doesn't match with your code snippet.

But as usual: If you have a NPE in line 250, there is a null object in this line.

What I see is that you create a bean for fetchBean?

Code: Select all
IBean rowUserLogin = new Bean();
rowUserLogin = dbVU.fetchBean(pFilter);

Its not necessary to do more than this:

Code: Select all
IBean rowUserLogin = dbVU.fetchBean(pFilter);


It's possible that fetchBean returns null if no user was found.

I would write the method a little bit different:

Code: Select all
IBean bean = getVUserSession().fetchBean(new Equals("USERNAME", TriggerAPI.getCurrentUserName()));
         
if (bean == null)
{
  //or return en empty string?
  throw new IllegalArgumentException("User was not found in User-Session list!");
}
else
{
  return rowUserLogin.get("EMPL_NAME");
}

And also your client code is not null aware:

[code]
Object result = getConnection().callAction("getUserEmplName");

if (result != null)
{
  labelUser.setText(result.toString());
}
else
{
  ???
}


Are you sure that the user-info should be set on Activate - every time? Isn't it good enough to retrieve the user-info only once after login?

But sure, it's you application and your business logic ;-)
johnit
 
Posts: 37
Joined: Fri Nov 16, 2012 5:58 pm

Re: callAction giving nullPointerException

Postby lucdep » Wed Nov 06, 2019 7:16 pm

Thanks for your reply. Things are working now.

Regards,

Luc
lucdep
 
Posts: 52
Joined: Wed Oct 10, 2018 12:01 pm


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