When I install the plugin through the Eclipse software installer as per the instructions at https://sourceforge.net/p/eclipsejsonedit/discussion/957258/thread/bc439e53/, I get the following error:
"Cannot complete the install because one or more required items could not be found.
Software being installed: JSON Editor Plugin 0.9.7 (jsonedit-feature.feature.group 0.9.7)
Missing requirement: JSON Editor Validator 0.9.7 (jsonedit-validator 0.9.7) requires 'bundle ch.qos.logback.classic 0.0.0' but it could not be found
Cannot satisfy dependency:
From: JSON Editor Plugin 0.9.7 (jsonedit-feature.feature.group 0.9.7)
To: jsonedit-validator [0.9.7]"
I will research further and report back.
I believe you need to install the plugin:
"Logging with SLF4J and Logback"
This should be available by choosing Help->Install New Software.
Selecting the Eclipse Download URL for your Eclipse version. e.g. for Juno the URL is:
Juno - http://download.eclipse.org/releases/juno/201209280900
then choosing "Logging with SLF4J and Logback" to install.
Hope that helps.