"Hotswap" or "Hotswapping" refers to dynamically replacing a class implementation during the runtime of an application.
JRebel is a plug-in for the Java Virtual Machine (JVM) that enables instant reloading of changes made to a Java class file.
|Much more powerful||
"It is worth mentioning that there is a commercial product named jrebel that is much more powerful than jvm hotswap"
from question "Java files do not reflect changes made in Dynamic Web Project in Eclipse EE"