Using a build tool (such as Ant) gives you the ability to do everything you need to in one go. For example, I have an ant build file which:
compiles all the source files in my project "java" directory and creates a "jar" file of the classes.compiles all the source files in my project "loadable" directory and places the class files in a "classes" directorycompiles and runs a complete unit test suite against the classes compiled above.runs a bunch of XML files through an XSLT styleheet to generate nicely decorated HTMLbuilds a complte "war" file from the jar file, loadable classes, generated HTML files, a "web.xml" file and some other resource files.copies the "war" file to a directory monitored by a local test webserverrestarts the test server if necessaryruns an acceptance test suite against the deployed applicationtransfers the "war" file to a remote server by FTPlogs in to the remote server using telnet and restarts its webserver. I can do all this just by typing "ant deploy". If any of the steps fail, the whole process stops with a sensible error message.
Can your IDE do this, or would you have to do most of it manually?