My corporate web application is using Java applet to access users file system. There is no way for us to replace it with anything else for now.
How do I enable Java in Microsoft Edge?
As other folks have mentioned, Java, ActiveX, Silverlight, Browser Helper Objects (BHOs) and other plugins are not supported in Microsoft Edge. Most modern browsers are moving away from plugins and toward standard HTML5 controls and technologies.
If you must continue to use the Java plugin in a corporate web app, consider adding the site to an Enterprise Mode site list. This will automatically prompt the user to open in IE.