Tips: Which are you using java command, JDK's or JRE's?

This is an easy tips. Which are you using java command, JDK's or JRE's? How do you recognize it? Let's type the command below:

> java -server -version
java version "1.7.0_02"
Java(TM) SE Runtime Environment (build 1.7.0_02-b13)
Java HotSpot(TM) 64-Bit Server VM (build 22.0-b10, mixed mode)

If succeed, that is JDK's , and if not, that is JRE's.