Ubuntu’s Eclipse package also depends on GCJ. If you wish to avoid this dependency, simply download the appropriate binary distribution from the Eclipse download site, extract to the location of your choice, and run Eclipse.

Before using Eclipse, be sure you have Sun’s JRE installed and configured as the default JRE.

Here’s how I installed Ant on Ubuntu without GCJ. Be sure to check out (easier) alternatives suggested in the comments, below.

1. Download the current .tar.bz2 distribution of Ant from http://www.ibiblio.org/pub/mirrors/apache/ant/binaries/.
2. Unpack archive using tar.

tar -xjvf apache-ant-*-bin.tar.bz2

3. Move the unpacked directory to /usr/local/ant.
4. Change that directory’s owner to root.

chown -R root:root /usr/local/ant

5. Add the following lines to /etc/bash.bashrc.

export ANT_HOME=/usr/local/ant
export PATH=${PATH}:${ANT_HOME}/bin

From a new shell, run ant. You should see the following:

Buildfile: build.xml does not exist!
Build failed

Yes, it’s a failure message. But it means Ant is working as expected.