Recently I started to use Eclipse's java compiler, because it is significantly faster than standard javac. I was told that it's faster because it performs incremental compiling. But I'm still a bit unsure about this since I can't find any authoritative documentation about both - eclispse's and sun's - compilers "incremental feature". Is it true that Sun's compiler always compiles every source file and Eclipse's compiler compile only changed files and those that are affected by such a change?

Edit: I'm not using Eclipse autobuild feature but instead I'm setting

```
-Dbuild.compiler=org.eclipse.jdt.core.JDTCompilerAdapter

```

for my ant builds.