Hi.
You need at least the java runtime environment (JRE).
But you can use a portable Version of Java, without installing it. This will not change any setting of your windows installation and Java will not be available in your browser.
http://portableapps.com/apps/utilities/java_portable

For more info check:
http://stackoverflow.com/questions/1619662/how-can-i-get-the-latest-jre-jdk-as-a-zip-file-rather-than-exe-or-msi-installe