Make sure that the build.xml is a part of your java project, and does not reside at a location that is external to the project. Enable Ant View by following Window > Show View > Other > Ant > Ant. Open Project Explorer, drag the build.xml into the Ant View.
If you have downloaded and installed Eclipse already, you have very little to do to get started. Eclipse comes pre bundled with the Ant plugin, ready to use. Follow the simple steps, to integrate Ant into Eclipse. Make sure that the build.xml is a part of your java project, and does not reside at a location that is external to the project. Enable Ant View by following Window > Show View > Other > Ant > Ant. Open Project Explorer, drag the build.xml into the Ant View.