Hi, I came across the same problem: Domain.getSchedulerParameters() throws a NullPointerException systematically. getSchedulerParameters The culprit is the org.libvirt.jna.virSchedParameterValue class which should inherit from jna.Union instead of Structure: public class virSchedParameterValue extends Union { ... } Regards, Frederic On 12/14/2009 04:22 AM, Marc Gonzalez Mateo wrote: OK, let's see if Bryan has an idea/solution about this. Thanks guys! MARC El 11/12/2009, a las 14:29, Daniel Veillard escribió: On Fri, Dec 11, 2009 at 02:01:36PM +0100, Marc Gonzalez Mateo wrote: Hi everyvody, I'm developing a new API based on libvirt. I'm currently stucked using getSchedulerParameters, always is returning a nullpointerexception, no matter which Xen Domain I'm passing to the function. Enclosing both the code and the error console: public int getCPUPriority(String name) { int res=-1; try { Domain d = getDomain(name); SchedParameter[] pars = d.getSchedulerParameters(); Hum, it seems Domain.getSchedulerParameters() does SchedParameter[] returnValue = new SchedParameter[0]; and public static SchedParameter create(virSchedParameter vParam) { SchedParameter returnValue = null; switch (vParam.type) { case (1): and the create method getting there gets a null pointer as the initialization argument, which it first dereference ... so not surprizing looking at the code, maybe Bryan has an idea of what is going on there, I'm a bit lost in this initialization process ... Daniel for (SchedParameter pri : pars) { if (pri.field=="weight") res=Integer.parseInt(pri.getValueAsString()); } } catch (LibvirtException e) { log.error(" Error: getting CPU priority of \""+name+"\"." + e.getClass()); e.printStackTrace(); } return res; } Dec 11, 2009 1:04:18 PM net.emotivecloud.virtmonitor.VirtMonitor getCPUCapacity SEVERE: Error: getting CPU capacity of "XenTest". java.lang.NullPointerException at org.libvirt.SchedParameter.create(Unknown Source) at org.libvirt.Domain.getSchedulerParameters(Unknown Source) at net.emotivecloud.virtmonitor.VirtMonitor.getCPUCapacity(VirtMonitor.java:462) at net.emotivecloud.virtmonitor.VirtMonitor.main(VirtMonitor.java:763) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:616) at org.codehaus.mojo.exec.ExecJavaMojo$1.run(ExecJavaMojo.java:283) at java.lang.Thread.run(Thread.java:636) Any ideas? Thanks in advance, Marc Gonzalez Mateo -- Libvir-list mailing list Libvir-list redhat com https://www.redhat.com/mailman/listinfo/libvir-list -- Daniel Veillard | libxml Gnome XML XSLT toolkit http://xmlsoft.org/ daniel veillard com | Rpmfind RPM search engine http://rpmfind.net/ http://veillard.com/ | virtualization library http://libvirt.org/ Frederic Dang Tran