java.lang.NoClassDefFoundError: java.awt.Container

I have had the same problem installing SoapUI software and this command works for me:

$ ./soapUI-x32-4.6.0.sh -J-Djava.awt.headless=true

My system:

Linux 3.10-2-amd64 #1 SMP Debian 3.10.7-1 (2013-08-17) x86_64 GNU/Linux

And my JVM version:

$ java -version
    java version "1.6.0_30"
    Java(TM) SE Runtime Environment (build 1.6.0_30-b12)
    Java HotSpot(TM) 64-Bit Server VM (build 20.5-b03, mixed mode)

On ubuntu 14.04 the answer given by Hayden didn't work for me as the package doesn't exist.

This did work though:

apt-get install libxtst6:i386

i.e. it needs the 32 bit version of libxtst