Maven - Why after "mvn clean" I need to execute "Maven Update Project" before "mvn package"?

Question

I'm making some tests and I would like to understand why after execute the command mvn clean I need to execute "Maven > Update Project" before run mvn package, otherwise I get a compilation error in one of my dependencies during the packaging.

It looks like my project doesn't compile correctly my project before running "Maven > Update Project", but I'm not sure. Is this normal?

• I'm using Eclipse and run the commands {mvn clean} and {mvn package} via "Run as > Maven Build".

Here is my 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>com.project</groupId>
    <artifactId>myProject</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>war</packaging>

    <properties>
        <jmockit.version>0.0.1</jmockit.version>
    </properties>

    <build>
        <testSourceDirectory>src/test/java/junit</testSourceDirectory>
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <excludes>
                    <exclude>**/*.java</exclude>
                </excludes>
            </resource>
        </resources>

        <testResources>
            <testResource>
                <directory>src/test/java/selenium</directory>
                <excludes>
                    <exclude>**/*.java</exclude>
                </excludes>
            </testResource>
        </testResources>

        <pluginManagement>
            <plugins>
                <!-- Need Java 5, which is the default since v2.3 of the maven-compiler-plugin. -->
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-compiler-plugin</artifactId>
                    <version>2.5.1</version>
                </plugin>
            </plugins>
        </pluginManagement>

        <plugins>
            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.6</source>
                    <target>1.6</target>
                </configuration>
            </plugin>
            <plugin>
                <artifactId>maven-war-plugin</artifactId>
                <version>2.2</version>
                <configuration>
                    <failOnMissingWebXml>false</failOnMissingWebXml>
                    <warSourceExcludes>src/main/resources/conf_development</warSourceExcludes>
                    <webResources>
                        <resource>
                            <directory>src/main/resources/conf_production</directory>
                            <targetPath>WEB-INF/classes/</targetPath>
                            <includes>
                                <include>**/*</include>
                            </includes>
                        </resource>
                        <resource>
                            <directory>src/main/resources/conf</directory>
                            <targetPath>WEB-INF/classes/</targetPath>
                            <includes>
                                <include>**/*</include>
                            </includes>
                        </resource>
                    </webResources>
                </configuration>
            </plugin>

            <plugin>
                <artifactId>maven-surefire-plugin</artifactId>
                <configuration>
                    <argLine>
                        -javaagent:"${settings.localRepository}"/mockit/jmockit/${jmockit.version}/jmockit-${jmockit.version}.jar
                    </argLine>
                </configuration>
            </plugin>
        </plugins>
    </build>


<dependencies>
    <dependency>
        <groupId>asm</groupId>
        <artifactId>asm</artifactId>
        <version>1.5.3</version>
    </dependency>
    <dependency>
        <groupId>bouncycastle</groupId>
        <artifactId>bcprov-jdk14</artifactId>
        <version>140</version>
    </dependency>
    <dependency>
        <groupId>c3p0</groupId>
        <artifactId>c3p0</artifactId>
        <version>0.9.1</version>
    </dependency>
    <dependency>
        <groupId>c3p0</groupId>
        <artifactId>c3p0-oracle-thin-extras</artifactId>
        <version>0.9.0.2</version>
    </dependency>
    <dependency>
        <groupId>commons-betwixt</groupId>
        <artifactId>commons-betwixt</artifactId>
        <version>0.7</version>
    </dependency>
    <dependency>
        <groupId>com.google.code.gson</groupId>
        <artifactId>gson</artifactId>
        <version>1.4</version>
    </dependency>
    <dependency>
        <groupId>org.apache.commons</groupId>
        <artifactId>commons-email</artifactId>
        <version>1.2</version>
    </dependency>
    <dependency>
        <groupId>net.sf.ehcache</groupId>
        <artifactId>ehcache-core</artifactId>
        <version>2.4.2</version>
    </dependency>
    <dependency>
        <groupId>com.googlecode.ehcache-spring-annotations</groupId>
        <artifactId>ehcache-spring-annotations</artifactId>
        <version>1.1.3</version>
    </dependency>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-annotations</artifactId>
        <version>3.4.0.GA</version>
    </dependency>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-entitymanager</artifactId>
        <version>3.4.0.GA</version>
    </dependency>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-core</artifactId>
        <version>3.3.2.GA</version>
    </dependency>
    <dependency>
        <groupId>org.apache.httpcomponents</groupId>
        <artifactId>httpclient</artifactId>
        <version>4.1.2</version>
    </dependency>
    <dependency>
        <groupId>net.sf.json-lib</groupId>
        <artifactId>json-lib</artifactId>
        <version>2.4</version>
        <type>pom</type>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-jdbc</artifactId>
        <version>2.5.6</version>
    </dependency>
    <dependency>
        <groupId>net.fckeditor</groupId>
        <artifactId>java-core</artifactId>
        <version>2.4</version>
    </dependency>
    <dependency>
        <groupId>backport-util-concurrent</groupId>
        <artifactId>backport-util-concurrent</artifactId>
        <version>3.1</version>
    </dependency>
    <dependency>
        <groupId>com.oracle</groupId>
        <artifactId>ojdbc14</artifactId>
        <version>10.2.0.1.0</version>
    </dependency>
    <dependency>
        <groupId>com.ibm.icu</groupId>
        <artifactId>icu4j</artifactId>
        <version>3.8</version>
    </dependency>
    <dependency>
        <groupId>mockit</groupId>
        <artifactId>jmockit</artifactId>
        <version>${jmockit.version}</version>
    </dependency>
    <dependency>
        <groupId>joda-time</groupId>
        <artifactId>joda-time</artifactId>
        <version>2.0</version>
    </dependency>
    <dependency>
        <groupId>com.lowagie</groupId>
        <artifactId>itext</artifactId>
        <version>2.1.0</version>
    </dependency>
    <dependency>
        <groupId>atg.taglib.json</groupId>
        <artifactId>json-taglib</artifactId>
        <version>0.4.1</version>
    </dependency>
    <dependency>
        <groupId>commons-httpclient</groupId>
        <artifactId>commons-httpclient</artifactId>
        <version>3.1</version>
    </dependency>
    <dependency>
        <groupId>net.sourceforge.jexcelapi</groupId>
        <artifactId>jxl</artifactId>
        <version>2.6</version>
    </dependency>
    <dependency>
        <groupId>log4j</groupId>
        <artifactId>log4j</artifactId>
        <version>1.2.17</version>
    </dependency>
    <dependency>
        <groupId>org.mockito</groupId>
        <artifactId>mockito-all</artifactId>
        <version>1.8.5</version>
    </dependency>
    <dependency>
        <groupId>org.quartz-scheduler</groupId>
        <artifactId>quartz</artifactId>
        <version>1.8.4</version>
    </dependency>
    <dependency>
        <groupId>org.seleniumhq.selenium</groupId>
        <artifactId>selenium-server</artifactId>
        <version>2.25.0</version>
        <type>pom</type>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring</artifactId>
        <version>2.5.6.SEC03</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-agent</artifactId>
        <version>2.5.6.SEC03</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-test</artifactId>
        <version>2.5.6.SEC03</version>
    </dependency>
    <dependency>
        <groupId>org.apache.struts</groupId>
        <artifactId>struts2-config-browser-plugin</artifactId>
        <version>2.2.1</version>
    </dependency>
    <dependency>
        <groupId>org.apache.struts</groupId>
        <artifactId>struts2-convention-plugin</artifactId>
        <version>2.2.1</version>
    </dependency>
    <dependency>
        <groupId>org.apache.struts</groupId>
        <artifactId>struts2-core</artifactId>
        <version>2.2.1</version>
    </dependency>
    <dependency>
        <groupId>org.apache.struts</groupId>
        <artifactId>struts2-jasperreports-plugin</artifactId>
        <version>2.2.1</version>
    </dependency>
    <dependency>
        <groupId>org.apache.struts</groupId>
        <artifactId>struts2-jfreechart-plugin</artifactId>
        <version>2.2.1</version>
    </dependency>
    <dependency>
        <groupId>org.apache.struts</groupId>
        <artifactId>struts2-json-plugin</artifactId>
        <version>2.2.1</version>
    </dependency>
    <dependency>
        <groupId>org.apache.struts</groupId>
        <artifactId>struts2-spring-plugin</artifactId>
        <version>2.2.1</version>
    </dependency>
    <dependency>
        <groupId>org.apache.velocity</groupId>
        <artifactId>velocity</artifactId>
        <version>1.6.3</version>
    </dependency>
    <dependency>
        <groupId>org.apache.velocity</groupId>
        <artifactId>velocity-tools</artifactId>
        <version>1.3</version>
    </dependency>
    <dependency>
        <groupId>com.yahoo.platform.yui</groupId>
        <artifactId>yuicompressor</artifactId>
        <version>2.4.6</version>
    </dependency>
    <dependency>
        <groupId>commons-lang</groupId>
        <artifactId>commons-lang</artifactId>
        <version>2.5</version>
    </dependency>
    <dependency>
        <groupId>net.sf.jodreports</groupId>
        <artifactId>jodreports</artifactId>
        <version>2.4.0</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.ws</groupId>
        <artifactId>spring-oxm</artifactId>
        <version>1.5.9</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.ws</groupId>
        <artifactId>spring-ws-core</artifactId>
        <version>1.5.9</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.ws</groupId>
        <artifactId>spring-oxm-tiger</artifactId>
        <version>1.5.9</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.ws</groupId>
        <artifactId>spring-ws-core-tiger</artifactId>
        <version>1.5.9</version>
    </dependency>
    <dependency>
        <groupId>javax.xml.bind</groupId>
        <artifactId>jaxb-api</artifactId>
        <version>2.1</version>
    </dependency>
    <dependency>
        <groupId>com.sun.xml.bind</groupId>
        <artifactId>jaxb-xjc</artifactId>
        <version>2.1</version>
    </dependency>
    <dependency>
        <groupId>org.apache.ws.commons.axiom
        </groupId>
        <artifactId>axiom-api</artifactId>
        <version>1.2.5</version>
    </dependency>
    <dependency>
        <groupId>org.apache.ws.commons.axiom
        </groupId>
        <artifactId>axiom-impl</artifactId>
        <version>1.2.5</version>
    </dependency>
    <dependency>
        <groupId>javax.xml</groupId>
        <artifactId>jaxrpc-api</artifactId>
        <version>1.1</version>
    </dependency>
    <dependency>
        <groupId>org.seleniumhq.selenium.client-drivers</groupId>
        <artifactId>selenium-java-client-driver</artifactId>
        <version>1.0.1</version>
    </dependency>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.11</version>
    </dependency>
    <dependency>
        <groupId>org.acegisecurity</groupId>
        <artifactId>acegi-security</artifactId>
        <version>1.0.7</version>
    </dependency>
    <dependency>
        <groupId>citizen</groupId>
        <artifactId>citizen</artifactId>
        <version>citizen</version>
    </dependency>
    <dependency>
        <groupId>jstl</groupId>
        <artifactId>jstl</artifactId>
        <version>1.2</version>
        <scope>provided</scope>
    </dependency>
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>servlet-api</artifactId>
        <version>2.4</version>
        <scope>provided</scope>
    </dependency>
    <dependency>
        <groupId>javax.servlet.jsp</groupId>
        <artifactId>jsp-api</artifactId>
        <version>2.0</version>
        <scope>provided</scope>
    </dependency>
    <dependency>
        <groupId>jasperreports</groupId>
        <artifactId>jasperreports</artifactId>
        <version>3.5.3</version>
    </dependency>
</dependencies>
</project>

The error:

(Remembering that the lib with error it's an internal lib and it work just fine after "Maven > Update Project")

[INFO] Compiling 2595 source files to C:\Users\user\Documents\Dev\workspace\project\target\classes
[INFO] -------------------------------------------------------------
[ERROR] COMPILATION ERROR : 
[INFO] -------------------------------------------------------------
[ERROR] C:\Users\user\Documents\Dev\workspace\project\src\main\java\com\project\jobs\citizen\model\service\CitizenService.java:[38
,34] cannot access org.apache.axis.client.Service
class file for org.apache.axis.client.Service not found
        Resolution2Locator r2 = new Resolution2Locator ();
[INFO] 1 error
[INFO] -------------------------------------------------------------
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 2:09.448s
[INFO] Finished at: Fri Mar 22 11:55:14 BRT 2013
[INFO] Final Memory: 25M/274M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:2.5.1:compile (default-compile) on project project: Compilation failure
[ERROR] C:\Users\user\Documents\Dev\workspace\project
\src\main\java\com\project\jobs\citizen\model\service\CitizenService.java:[38
,34] cannot access org.apache.axis.client.Service
[ERROR] class file for org.apache.axis.client.Service not found
[ERROR] Resolution2Locator r2 = new Resolution2Locator();
[ERROR] -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:2.5.1:compile (default-compile) on project u
nico: Compilation failure
C:\Users\user\Documents\Dev\workspace\project\src\main\java\com\project\jobs\citizen\model\service\CitizenService.java:[38,34] can
not access org.apache.axis.client.Service
class file for org.apache.axis.client.Service not found
        Resolution2Locator r2 = new Resolution2Locator ();

    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:213)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:84)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:59)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.singleThreadedBuild(LifecycleStarter.java:183)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:161)
    at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:320)
    at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:156)
    at org.apache.maven.cli.MavenCli.execute(MavenCli.java:537)
    at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:196)
    at org.apache.maven.cli.MavenCli.main(MavenCli.java:141)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:290)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:230)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:409)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:352)
Caused by: org.apache.maven.plugin.CompilationFailureException: Compilation failure
C:\Users\user\Documents\Dev\workspace\project\src\main\java\com\project\jobs\citizen\model\service\CitizenService.java:[38,34] can
not access org.apache.axis.client.Service
class file for org.apache.axis.client.Service not found
        Resolution2Locator r2 = new Resolution2Locator ();

    at org.apache.maven.plugin.AbstractCompilerMojo.execute(AbstractCompilerMojo.java:729)
    at org.apache.maven.plugin.CompilerMojo.execute(CompilerMojo.java:128)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:101)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:209)
    ... 19 more
[ERROR] 
[ERROR] 
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoFailureException

Answer 1

Here is what happens:

1. mvn clean deletes the target directory
2. mvn package performs some work, but then encounters a compilation error due to a missing dependency. That's why the target folder is in error.
3. Running Maven > Update Project in Eclipse causes Eclipse to perform its own compilation, separate from Maven. Eclipse has a different classpath than Maven, so its compilation succeeds. Now the target directory has all the compiled classes.
4. Re-running mvn package now succeeds, because it finds all the classes already compiled and doesn't need to perform any compilation.

Ultimately, the problem is in the project configuration in pom.xml. I had the same problem, and after adding the missing dependency I successfully compiled project with Maven.

Answer 2

The Eclipse m2e plugin (this is a simplification) reads the POM file and translates it into instructions for Eclipse so that Eclipse can do its thing. Because Eclipse is in control the whole time, your view gets updated correctly and things are pretty smooth. Some more advanced Maven actions with plugins are not supported by m2e, and so those actions just won't happen. Some simple stuff, like the classpath is different from how Maven does things -- m2e uses the "test" classpath no matter what because Eclipse can't predict what you'll want to run.

On the other hand, performing "Run as > Maven ..." actually calls Maven, a program completely outside of Eclipse, and asks it to run. Eclipse doesn't automatically know when files have been created or deleted by Maven.

I would generally stay away from the "Run as > Maven" commands. The integration is poor, the Eclipse console interface is ugly, it's just easier to call mvn from the command line if you need to run specific Maven goals.

If you just want to develop a Maven project, I find the m2e integration works very well. I use Jenkins to handle the packaging and deployment for me, so I'm only using Eclipse to edit and test my code.