SWT chart GTK3 not available error

[YuGen Xu]

Hello

in ubuntu 20.04, GTK version 3.24.30,

I use

the https://github.com/jzy3d/jzy3d-api/blob/master/jzy3d-native-jogl-swt/src/main/java/org/jzy3d/demos/SurfaceDemoSWT.java

example

 but I get a GTK not available error

java.lang.ExceptionInInitializerError
at com.jogamp.newt.swt.NewtCanvasSWT.<init>(NewtCanvasSWT.java:135)
at org.jzy3d.chart.factories.CanvasNewtSWT.<init>(CanvasNewtSWT.java:60)
at org.jzy3d.chart.factories.SWTPainterFactory.newCanvas(SWTPainterFactory.java:63)
at org.jzy3d.chart.Chart.<init>(Chart.java:106)
at org.jzy3d.chart.factories.SWTChart.<init>(SWTChart.java:12)
at org.jzy3d.chart.factories.SWTChartFactory.newChart(SWTChartFactory.java:47)
at org.jzy3d.chart.factories.ChartFactory.newChart(ChartFactory.java:70)

Caused by: com.jogamp.nativewindow.NativeWindowException: com.jogamp.common.JogampRuntimeException: org.eclipse.swt.internal.gtk3.GTK3 not available
at com.jogamp.nativewindow.swt.SWTAccessor.<clinit>(SWTAccessor.java:295)
... 111 more
Caused by: com.jogamp.common.JogampRuntimeException: org.eclipse.swt.internal.gtk3.GTK3 not available
at com.jogamp.common.util.ReflectionUtil.getClass(ReflectionUtil.java:174)
at com.jogamp.nativewindow.swt.SWTAccessor.<clinit>(SWTAccessor.java:278)
... 111 more

My jzy3d version is 2.2.1 (jzy3d-native-jogl-swt is 2.0.0)

how to fix this error?