This works for me on CentOS 7 after installing JRE 9.0.4
Make sure to override the GDK_SCALE environment variable if you need to:
env GDK_SCALE=2 /usr/java/jre-9.0.4/bin/java --add-exports=java.desktop/com.sun.java.swing.plaf.windows=ALL-UNNAMED --add-exports=java.desktop/com.apple.laf=ALL-UNNAMED -jar yed.jar
I do get some warnings in my terminal:
WARNING: package com.apple.laf not in java.desktop
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by com.jidesoft.swing.JideTabbedPane (file:/opt/yEd/yed.jar) to field javax.swing.JTabbedPane.visComp
WARNING: Please consider reporting this to the maintainers of com.jidesoft.swing.JideTabbedPane
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release
I haven't tested the full stability of yEd with this new JRE, but I can confirm it opens with the correct Display Scale; only in JRE 9.
David