Use the Best Font Rendering Available

The Linux font rendering issue (JDK-8212071) has been fixed in Java 12 build 30, that fix is backported to JDK 11.0.6. if you use that build or later Java to run NetBeans with you are going to get an excellent Font rendering.

Note: Due to these font rendering issues the Snap package comes with a preset of the awt.useSystemAAFontSettings=on property. It can removed by:

mkdir -p $HOME/snap/netbeans/current/etc/
cp /snap/netbeans/current/netbeans/etc/netbeans.conf $HOME/snap/netbeans/current/etc/
gedit $HOME/snap/netbeans/current/etc/netbeans.conf

Ugly Fonts on Ubuntu with Java 9, 10

For some reason there were a few packages of JDK out where the fontconfig.Ubuntu.properties file was present in the lib directory of the JDK.
That file was used to tune the used typesetting details in the pre-Ubuntu Font era. Having that in place would result to render replacements of possible not installed fonts. So Java displays an ugly user interface.

Solution:

Remove the fontconfig.Ubuntu.properties file from the lib directory of the JDK.

Washed out (reddish blur) Fonts on Linux with Oracle Java 11

For whatever reason Oracle changed the font rendering routines again, and removed the fonts previously delivered with Java in Java 11.

It happens as the anti-aliasing setting is wrongly detected by default.

Start NetBeans (or add the following parameter to netbeans.cfg) with:  -J-Dawt.useSystemAAFontSettings=on

It is also recommended to set the Gnome/KDE hinting level to medium or full.

Ugly Wrong Sized Fonts in Terminal

Sometimes Terminal could really present interesting display experiences.

Solution:

Try the latest NetBeans release since this was fixed via https://github.com/apache/netbeans/pull/6163