Developing code needs debugging. Java has very good facilities to debug code during development. JVM supports debuggers via the Java Platform Debugger Architecture. This lets you execute code in debug mode, and JVM will accept external debugger tools to attach to it via a network, or it will try to attach to a debugger depending on command-line options. JDK contains a client, the jdb tool, which contains a debugger; however, it is so cumbersome to use when compared to the graphical client built into the IDEs that I have never heard of anyone using it for real work.
To start a Java program in debug mode so that JVM will accept a debugger client to attach the options to it, execute the following command:
-Xagentlib:jdwp=transport=dt_socket,server=y,suspend=y,address=7896 ...
