try run it from command to get the start logs, i.e.,
<ORACLE_HOME>/jdeveloper/jdev/bin/jdev
I got error:
Oracle JDeveloper 12c Development Build 12.2.1.0.0
Copyright (c) 1997, 2015, Oracle and/or its affiliates. All rights reserved.
java.lang.RuntimeException: Exception in org.eclipse.osgi.framework.internal.core.SystemBundleActivator.start() of bundle org.eclipse.osgi.
at org.eclipse.osgi.framework.internal.core.InternalSystemBundle.resume(InternalSystemBundle.java:233)
at org.eclipse.osgi.framework.internal.core.Framework.launch(Framework.java:656)
Now you have delete the system_cache folder located /Users/<user>/.jdeveloper/system12.1.3.0.41.140521.1008/system_cache
And jdeveloper start again