最近无意间看源码的时候，有个作者推荐了一款ASM Bytecode outline的插件，说是可以在IDEA上查看JVM的字节码，小弟在本地试了下，发现这个插件会报如下错误：
java.lang.IllegalArgumentException: Argument for @NotNull parameter 'module' of com/intellij/openapi/roots/ModuleRootManager.getInstance must not be null at com.intellij.openapi.roots.ModuleRootManager.$$$reportNull$$$0(ModuleRootManager.java) at com.intellij.openapi.roots.ModuleRootManager.getInstance(ModuleRootManager.java) at com.intellij.openapi.roots.CompilerModuleExtension.getInstance(CompilerModuleExtension.java:20) at org.objectweb.asm.idea.ShowBytecodeOutlineAction.actionPerformed(ShowBytecodeOutlineAction.java:85) at com.intellij.openapi.actionSystem.ex.ActionUtil.lambda$performActionDumbAwareWithCallbacks$4(ActionUtil.java:244) at com.intellij.openapi.actionSystem.ex.ActionUtil.performDumbAwareWithCallbacks(ActionUtil.java:265) at com.intellij.openapi.actionSystem.ex.ActionUtil.performActionDumbAwareWithCallbacks(ActionUtil.java:244) at com.intellij.openapi.actionSystem.impl.ActionMenuItem$ActionTransmitter.lambda$performAction$0(ActionMenuItem.java:277) at com.intellij.openapi.wm.impl.FocusManagerImpl.runOnOwnContext(FocusManagerImpl.java:236) at com.intellij.openapi.wm.impl.IdeFocusManagerImpl.runOnOwnContext(IdeFocusManagerImpl.java:67) at com.intellij.openapi.actionSystem.impl.ActionMenuItem$ActionTransmitter.performAction(ActionMenuItem.java:269) at com.intellij.openapi.actionSystem.impl.ActionMenuItem$ActionTransmitter.actionPerformed(ActionMenuItem.java:284) at java.desktop/javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1967) at com.intellij.openapi.actionSystem.impl.ActionMenuItem.lambda$fireActionPerformed$2(ActionMenuItem.java:111) at com.intellij.openapi.application.TransactionGuardImpl.performUserActivity(TransactionGuardImpl.java:94) at com.intellij.openapi.actionSystem.impl.ActionMenuItem.fireActionPerformed(ActionMenuItem.java:111) at com.intellij.ui.plaf.beg.BegMenuItemUI.doClick(BegMenuItemUI.java:541) at com.intellij.ui.plaf.beg.BegMenuItemUI$MyMenuDragMouseHandler.menuDragMouseReleased(BegMenuItemUI.java:603) at java.desktop/javax.swing.JMenuItem.fireMenuDragMouseReleased(JMenuItem.java:575) at java.desktop/javax.swing.JMenuItem.processMenuDragMouseEvent(JMenuItem.java:472) at java.desktop/javax.swing.JMenuItem.processMouseEvent(JMenuItem.java:417) at java.desktop/javax.swing.MenuSelectionManager.processMouseEvent(MenuSelectionManager.java:342) at com.intellij.ui.plaf.beg.BegMenuItemUI$MyMouseInputHandler.mouseReleased(BegMenuItemUI.java:573) at java.desktop/java.awt.Component.processMouseEvent(Component.java:6654) at java.desktop/javax.swing.JComponent.processMouseEvent(JComponent.java:3345) at java.desktop/java.awt.Component.processEvent(Component.java:6419) at java.desktop/java.awt.Container.processEvent(Container.java:2263) at java.desktop/java.awt.Component.dispatchEventImpl(Component.java:5029) at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2321) at java.desktop/java.awt.Component.dispatchEvent(Component.java:4861) 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:2790) at java.desktop/java.awt.Component.dispatchEvent(Component.java:4861) at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:778) at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:727) at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:721) at java.base/java.security.AccessController.doPrivileged(Native Method) at java.base/java.security.ProtectionDomain$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:751) at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:749) at java.base/java.security.AccessController.doPrivileged(Native Method) at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:85) at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:748) at com.intellij.ide.IdeEventQueue.defaultDispatchEvent(IdeEventQueue.java:891) at com.intellij.ide.IdeEventQueue.dispatchMouseEvent(IdeEventQueue.java:820) at com.intellij.ide.IdeEventQueue._dispatchEvent(IdeEventQueue.java:757) at com.intellij.ide.IdeEventQueue.lambda$dispatchEvent$6(IdeEventQueue.java:447) at com.intellij.openapi.progress.impl.CoreProgressManager.computePrioritized(CoreProgressManager.java:818) at com.intellij.ide.IdeEventQueue.lambda$dispatchEvent$7(IdeEventQueue.java:446) at com.intellij.openapi.application.impl.ApplicationImpl.runIntendedWriteActionOnCurrentThread(ApplicationImpl.java:805) at com.intellij.ide.IdeEventQueue.dispatchEvent(IdeEventQueue.java:498) 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)
大致原因是IDEA编译器缺少某些组件，导致这个ASM Bytecode Outline无法启动成功。因此我在plugin插件市场上搜了下其他的类似插件，发现只有这个ASM Bytecode Viewer可用。
装上之后完美运行。 具体用法是：在complie的class字节码文件上直接右键选择ASM Bytecode Viewer即可展示指令码。
