If you only use the standard eclipse build system, you end up using the eclipse java compiler:
$ aptitude show libecj-java
Paket: libecj-java
...
Beschreibung: Eclipse Java compiler (library)
This package provides a standalone version of the Eclipse JDT compiler library
which is distributed as part of Eclipse. It passes the JCK (Java Compatibility
Kit) and is compatible with Java 1.3, 1.4, 1.5, 1.6 and 1.7.
Maybe you use external builds in your projects?
If you want or have to use javac on the command line, you have to install an jdk.
If you only use the standard eclipse build system, you end up using the eclipse java compiler:
$ aptitude show libecj-java
Paket: libecj-java
...
Beschreibung: Eclipse Java compiler (library)
This package provides a standalone version of the Eclipse JDT compiler library
which is distributed as part of Eclipse. It passes the JCK (Java Compatibility
Kit) and is compatible with Java 1.3, 1.4, 1.5, 1.6 and 1.7.
Maybe you use external builds in your projects?
If you want or have to use javac on the command line, you have to install an jdk.