Exception in thread "AWT-EventQueue-0" java.lang.NoClassDefFoundError: javax/servlet/ServletOutputStream
at net.sf.jasperreports.web.util.WebResourceHandlersExtensionRegistryFactory.< clinit>(WebResourceHandlersExtensionRegistryFactory.java:47)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:348)
at net.sf.jasperreports.engine.util.JRClassLoader.loadClassForRealName(JRClass Loader.java:157)
at net.sf.jasperreports.engine.util.JRClassLoader.loadClassForName(JRClassLoad er.java:115)
at net.sf.jasperreports.engine.util.ClassUtils.instantiateClass(ClassUtils.jav a:53)
at net.sf.jasperreports.extensions.DefaultExtensionsRegistry.instantiateRegist ry(DefaultExtensionsRegistry.java:237)
at net.sf.jasperreports.extensions.DefaultExtensionsRegistry.loadRegistries(De faultExtensionsRegistry.java:214)
at net.sf.jasperreports.extensions.DefaultExtensionsRegistry.loadRegistries(De faultExtensionsRegistry.java:162)
at net.sf.jasperreports.extensions.DefaultExtensionsRegistry.getRegistries(Def aultExtensionsRegistry.java:133)
at net.sf.jasperreports.extensions.DefaultExtensionsRegistry.getExtensions(Def aultExtensionsRegistry.java:105)
at net.sf.jasperreports.engine.util.JRStyledTextParser.<clinit>(JRStyledTextPa rser.java:83)
at net.sf.jasperreports.engine.fill.JRBaseFiller.<init>(JRBaseFiller.java:121)
at net.sf.jasperreports.engine.fill.JRVerticalFiller.<init>(JRVerticalFiller.j ava:88)
at net.sf.jasperreports.engine.fill.JRVerticalFiller.<init>(JRVerticalFiller.j ava:103)
at net.sf.jasperreports.engine.fill.JRVerticalFiller.<init>(JRVerticalFiller.j ava:61)
at net.sf.jasperreports.engine.fill.JRFiller.createFiller(JRFiller.java:179)
at net.sf.jasperreports.engine.fill.JRFiller.fill(JRFiller.java:81)
at net.sf.jasperreports.engine.JasperFillManager.fill(JasperFillManager.java:4 46)
at net.sf.jasperreports.engine.JasperFillManager.fill(JasperFillManager.java:2 76)
at net.sf.jasperreports.engine.JasperFillManager.fillReport(JasperFillManager. java:745)
at klinik.stok_obat.blsoActionPerformed(stok_obat.java:414)
at klinik.stok_obat.access$1000(stok_obat.java:19)
at klinik.stok_obat$11.actionPerformed(stok_obat.java:308)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2346 )
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java: 402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListene r.java:252)
at java.awt.Component.processMouseEvent(Component.java:6525)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
at java.awt.Component.processEvent(Component.java:6290)
at java.awt.Container.processEvent(Container.java:2234)
at java.awt.Component.dispatchEventImpl(Component.java:4881)
at java.awt.Container.dispatchEventImpl(Container.java:2292)
at java.awt.Component.dispatchEvent(Component.java:4703)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4898)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4533)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4462)
at java.awt.Container.dispatchEventImpl(Container.java:2278)
at java.awt.Window.dispatchEventImpl(Window.java:2750)
at java.awt.Component.dispatchEvent(Component.java:4703)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.j ava:75)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.j ava:86)
at java.awt.EventQueue$4.run(EventQueue.java:731)
at java.awt.EventQueue$4.run(EventQueue.java:729)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.j ava:75)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.jav a:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:1 16)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.jav a:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
Caused by: java.lang.ClassNotFoundException: javax.servlet.ServletOutputStream
at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)

kalo yg ngalamin kaya ane dan kebetulan ini udah solved di ane berbagi ilmunya ada nih
pertama2 download servlet-api di http://www.java2s.com/Code/Jar/s/Dow...vletapijar.htm
abis itu add jar/folder di library lalu masukin servlet-api yg tadi di download
dan running lg viola it work