[Solved]-Android Device Monitor will not start-eclipse

1. make sure the java_home environment variable refers to the correct java runtime environment location on your c:\ drive.
2. make sure you launch the 64-bit verions of eclipse or android studio.

try to modify your monitor.ini file present in tools/lib/monitor-x86 folder. first of all backup it, then replace the content of this file with

-xms256m
-xmx512m

now rerun monitor.bat. hopefully this will fix your issue.

i was also facing the same problem. i have also tried running android device monitor via monitor.bat but i get the following error in the log file

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:86)
    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(unknown source)
    at sun.reflect.delegatingmethodaccessorimpl.invoke(unknown source)
    at java.lang.reflect.method.invoke(unknown source)
    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)

reference: https://stackoverflow.com/a/25159856/2073920