mvn compiler:compile works, mvn compile not - maven

Question

I have a project with a maven pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>Minimal-J</groupId>
<artifactId>Minimal-J</artifactId>
<version>0.1-SNAPSHOT</version>
<name>Minimal-J</name>
<dependencies>
<dependency>
<groupId>org.apache.derby</groupId>
<artifactId>derby</artifactId>
<version>10.8.2.2</version>
</dependency>
<dependency>
<groupId>org.apache.derby</groupId>
<artifactId>derbyclient</artifactId>
<version>10.8.2.2</version>
</dependency>
<dependency>
<groupId>com.vaadin</groupId>
<artifactId>vaadin</artifactId>
<version>6.7.6</version>
</dependency>
<dependency>
<groupId>org.apache.lucene</groupId>
<artifactId>lucene-core</artifactId>
<version>3.4.0</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.8.2</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>com.miglayout</groupId>
<artifactId>miglayout</artifactId>
<version>3.7.4</version>
</dependency>
<dependency>
<groupId>commons-dbutils</groupId>
<artifactId>commons-dbutils</artifactId>
<version>1.4</version>
</dependency>
<dependency>
<groupId>org.json</groupId>
<artifactId>json</artifactId>
<version>20090211</version>
</dependency>
<dependency>
<groupId>com.google.gwt</groupId>
<artifactId>gwt-user</artifactId>
<version>2.3.0</version>
</dependency>
<dependency>
<groupId>com.google.gwt</groupId>
<artifactId>gwt-dev</artifactId>
<version>2.3.0</version>
<scope>provided</scope>
</dependency>
</dependencies>
<packaging>pom</packaging>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
</project>
if I execute
mvn compiler:compile
all 189 of my java classes are compiled
[INFO] Scanning for projects...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building Minimal-J 0.1-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] --- maven-compiler-plugin:2.4:compile (default-cli) # Minimal-J ---
[INFO] Compiling 189 source files to C:\projects\open-ech\workspace\minimal-j\MinimalJ\target\classes
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 4.386s
[INFO] Finished at: Fri May 11 11:50:54 CEST 2012
[INFO] Final Memory: 13M/37M
[INFO] ------------------------------------------------------------------------
if I simply type
mvn compile
Nothing seems to be done:
[INFO] Scanning for projects...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building Minimal-J 0.1-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 0.120s
[INFO] Finished at: Fri May 11 11:53:36 CEST 2012
[INFO] Final Memory: 1M/15M
[INFO] ------------------------------------------------------------------------
In a other project everything works fine.
Where could I possibly have configured something wrong to trigger this behaviour?

Answer 1

It's because of pom packaging. By invoking mvn compiler:compile you run compile goal outside Maven's default lifecycle and that basically compile sources in src/main/java. And by mvn compile you run lifecycle up to compile phase and the actual goals executed in every single phase depend on project's packaging type then. pom-type project does nothing in compile phase, because - in fact - there is nothing to compile with just POM.
I suppose your intention was to have jar packaging and changing that should help.