解决方案:
[title]1、在任务管理器进程里面关掉所有 monitor.exe 进程。[/title]

[title]2、再去删除monitor-workspace整个目录，我的在C:UsersAdministrator.android里面，删除完重新打开成功。[/title]

主要报错代码
!ENTRY org.eclipse.osgi 4 0 2018-07-10 12:15:58.357
!MESSAGE Application error
!STACK 1
java.lang.NullPointerException
at org.eclipse.core.runtime.URIUtil.toURI(URIUtil.java:280)
at org.eclipse.e4.ui.internal.workbench.ResourceHandler.loadMostRecentModel(ResourceHandler.java:127)
at org.eclipse.e4.ui.internal.workbench.swt.E4Application.loadApplicationModel(E4Application.java:370)
at org.eclipse.e4.ui.internal.workbench.swt.E4Application.createE4Workbench(E4Application.java:220)
at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:557)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:543)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at com.android.ide.eclipse.monitor.MonitorApplication.start(MonitorApplication.java:63)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:353)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:180)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:629)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:584)
at org.eclipse.equinox.launcher.Main.run(Main.java:1438)
 
 
参考: https://blog.csdn.net/cswhale/article/details/77679623