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Java: Can't find symbol: class name, when the class name in one of two packages with the same name [duplicate]

I use maven to build a multi module project. My module 2 depends on Module 1 src at compile scope and module 1 tests in test scope.
Module 2 -
<dependency>
<groupId>blah</groupId>
<artifactId>MODULE1</artifactId>
<version>blah</version>
<classifier>tests</classifier>
<scope>test</scope>
</dependency>
This works fine. Say my module 3 depends on Module1 src and tests at compile time.
Module 3 -
<dependency>
<groupId>blah</groupId>
<artifactId>MODULE1</artifactId>
<version>blah</version>
<classifier>tests</classifier>
<scope>compile</scope>
</dependency>
When I run mvn clean install, my build runs till module 3, fails at module 3 as it couldn't resolve the module 1 test dependency. Then I do a mvn install on module 3 alone, go back and run mvn install on my parent pom to make it build. How can I fix this?

I have a doubt about what you are trying to do but but I'll assume you want to reuse the tests that you have created for a project (module1) in another. As explained in the note at the bottom of the Guide to using attached tests:
Note that previous editions of this guide suggested to use <classifier>tests</classifier> instead of <type>test-jar</type>. While this currently works for some cases, it does not properly work during a reactor build of the test JAR module and any consumer if a lifecycle phase prior to install is invoked. In such a scenario, Maven will not resolve the test JAR from the output of the reactor build but from the local/remote repository. Apparently, the JAR from the repositories could be outdated or completely missing, causing a build failure (cf. MNG-2045).
So, first, to package up compiled tests in a JAR and deploy them for general reuse, configure the maven-jar-plugin as follows:
<project>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<version>2.2</version>
<executions>
<execution>
<goals>
<goal>test-jar</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
Then, install/deploy the test JAR artifact as usual (using mvn install or mvn deploy).
Finally, to use the test JAR, you should specify a dependency with a specified type of test-jar:
<project>
...
<dependencies>
<dependency>
<groupId>com.myco.app</groupId>
<artifactId>foo</artifactId>
<version>1.0-SNAPSHOT</version>
<type>test-jar</type>
<scope>test</scope>
</dependency>
</dependencies>
...
</project>

Regarding to my comment to Pascals question i think i have found a stuitable answer :
<plugins>
<plugin>
<artifactId>maven-jar-plugin</artifactId>
<version>2.2</version>
<executions>
<execution>
<goals>
<goal>test-jar</goal>
</goals>
<phase>test-compile</phase>
</execution>
</executions>
<configuration>
<outputDirectory>${basedir}\target</outputDirectory>
</configuration>
</plugin>
</plugins>
The main difference here as you see here is the <phase> tag.
I will create the test-jar and it will be available in the compile phase of the tests and not only after the package phase.
Works for me.

Local non maven jar is searching on maven server. Why?

[ERROR] Failed to execute goal on project portal: Could not resolve dependencies for project com.learning:portal:war:1.0.0-SNAPSHOT: Could not find artifact com.myapp.Local-2017:jar:1.0 in central (https://repo.maven.apache.org/maven2)
In pom.xml:
<dependency>
<groupId>com.myapp.Local</groupId>
<artifactId>Local-2017</artifactId>
<version>1.0</version>
</dependency>
Plugins:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-install-plugin</artifactId>
<version>2.5</version>
<executions>
<execution>
<phase>clean</phase>
<configuration>
<repositoryLayout>default</repositoryLayout>
<groupId>com.myapp.Local</groupId>
<artifactId>Local-2017</artifactId>
<version>1.0</version>
<packaging>jar</packaging>
<file>${basedir}/lib/Local.jar</file>
<generatePom>true</generatePom>
</configuration>
<goals>
<goal>install-file</goal>
</goals>
</execution>
</executions>
</plugin>

You declared a Maven dependency
<dependency>
<groupId>com.myapp.Local</groupId>
<artifactId>Local-2017</artifactId>
<version>1.0</version>
</dependency>
If Maven does not find it in your local repository, it will try to download it from outside. If you do not have a settings.xml it will try MavenCentral.

I suspect that part of the problem is that you have put the execution of "maven-install-plugin" into the "clean" phase. According to the Maven 3.5 Documentation, the "clean" phase is part of the "clean" life-cycle; i.e. gets run when you run "mvn clean".
I think it should be in the "default" lifecycle, probably the "validate" or "initialize" phase. Note that dependency resolution typically occurs in a later phase. It happens in the first phase that uses a plugin that requires dependency resolution as a prerequisite. Put the "install-file" goal into an earlier phase in the lifecycle.

Cancel maven exclusions from parent project in child project

I have the following in my pom
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>1.7.13</version>
<!-- <scope>compile</scope>-->
</dependency>
</dependencies>
</dependencyManagement>
<dependencies>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>1.7.13</version>
<!-- <scope>compile</scope>-->
</dependency>
Basically, I want to include slf4j-log4j12 as a dependency. However, when I do mvn clean install, I get the following error:
[INFO] log4j:log4j:jar was excluded in DepMgt, but version 1.2.17 has been found in the dependency tree.
[INFO] org.slf4j:slf4j-log4j12:jar was excluded in DepMgt, but version 1.7.13 has been found in the dependency tree.
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-dependency-plugin:2.10:analyze-dep-mgt (analyze-dependency) on project my-project: Found Dependency errors. -> [Help 1]
This library seems to have been excluded in the parent project. Is there a way to cancel the exclusion and include it in this project?
EDIT
I tried adding this
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<version>2.10</version>
<executions>
<execution>
<goals>
<goal>
analyze-dep-mgt
</goal>
</goals>
</execution>
</executions>
<configuration>
<skip>true</skip>
</configuration>
</plugin>
</plugins>
</build>
But I still get the same error.
EDIT2
I could make it work by using this
<properties>
<analyze.dependency.skip>true</analyze.dependency.skip>
</properties>
But, is it possible for skip for my dependency only.

Your parent pom includes the following plugin
org.apache.maven.plugins:maven-dependency-plugin:2.10:analyze-dep-mgt
This checks the consistency in the dependencies (You can look it up by downloading the parent pom).
Declare the plugin again and set <skip> to true to avoid this check.
Alternatively: If your parent pom defines a property which you can set to skip the execution, set this property to false.

Maven won't exclude during copy-dependencies

I have a project that uses Netty 4.0.29 and I have another dependency that pulls in netty 3.9.0. I put in an exclusion but it is still roping in 3.9.0 when I run copy-dependencies.
<dependency>
<groupId>com.ning</groupId>
<artifactId>async-http-client</artifactId>
<version>1.9.31</version>
<exclusions>
<exclusion>
<groupId>io.netty</groupId>
<artifactId>netty</artifactId>
</exclusion>
</exclusions>
</dependency>
If I run mvn dependency:tree with this exclusion in place, I see that it is indeed excluded:
[INFO] +- com.ning:async-http-client:jar:1.9.31:compile
But when I run mvn clean dependency:copy-dependencies I see the jar 3.9.0 being copied along with the 4.0.29. According to the documentation and Google, this should not copy when there is an exclusion.
[INFO] Copying netty-3.9.0.Final.jar to /Users/udonom1/wk/141/coursecopy-api/target/dependency/netty-3.9.0.Final.jar
[INFO] Copying netty-all-4.0.29.Final.jar to /Users/udonom1/wk/141/coursecopy-api/target/dependency/netty-all-4.0.29.Final.jar
I tried excluding as suggested by the first answer below and that did not work.
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<version>2.1</version>
<executions>
<execution>
<id>copy-dependencies</id>
<phase>process-sources</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
<configuration> <outputDirectory>${project.build.directory}/lib</outputDirectory>
<overWriteReleases>false</overWriteReleases>
<overWriteSnapshots>false</overWriteSnapshots>
<overWriteIfNewer>true</overWriteIfNewer>
<excludeArtifactIds>io.netty:netty:3.9.0.Final</excludeArtifactIds>
</configuration>
</execution>
</executions>
</plugin>
I also added a dependency as further suggested:
<dependency>
<groupId>io.netty</groupId>
<artifactId>netty-all</artifactId>
<version>4.0.29.Final</version>
</dependency>
What am I doing wrong?

For those who are having the same issue. I used mvn -X and discovered that dependency:tree is omitting two other jars that are referencing netty. I added exclusions for those and I'm good to go. Spent a whole day on this.

If you are writing not library you have simple way to control versions of any dependency in your project - dependencyManagement block in root pom file, example:
<dependencyManagement>
<dependencies>
<dependency>
<groupId>io.netty</groupId>
<artifactId>netty</artifactId>
<version>4.0.29.Final</version>
</dependency>
</dependencies>
</dependencyManagement>
Additional bonuses from this block - you can omit version and scope for dependency in concrete dependency (with same group id, artifact id and packaging).
PS another look to your dependencies make me ask you: are you sure that this dependency have single maven artifact id? netty-all-4.0.29.Final.jar - seems that this artifact should have netty-all artifact id... If they have different artifact id's my recipe wouldn't help. In this case you should define build configuration for maven-dependency-plugin, example:
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<version>2.10</version>
<configuration>
<excludeArtifactIds>io.netty:netty:3.9.0.Final</excludeArtifactIds>
</configuration>
</plugin>
</plugins>
</build>
or just use -DexcludeArtifactIds parameter in your maven call

Proguard with Maven

I am trying to use Proguard to shrink the jar size.
I configured Proguard in Maven pom.xml. It failed to find all the embedded dependency jars.
It can read and parse out all dependency jars which is referenced in the current module, but for dependencies which are embedded in the other modules, it failed to find it.
For example, My current module is moduleA and it depends another module moduleB. And module B has a dependency moduleC. It can find all classes which are directly inside moduleB, but it failed to parse out all classes which are inside moduleC. My configuration for proguard is as following:
<plugin>
<!--groupId>com.pyx4me</groupId-->
<groupId>com.github.wvengen</groupId>
<artifactId>proguard-maven-plugin</artifactId>
<executions>
<execution>
<id>proguard</id>
<phase>package</phase>
<goals>
<goal>proguard</goal>
</goals>
</execution>
</executions>
<configuration>
<injar>MyInput-${project.version}.jar</injar>
<outjar>MyInput-Processed-${project.version}.jar</outjar>
<options>
<option>-keep public class * { *; }</option>
<option>-ignorewarnings</option>
</options>
<libs>
<!--lib>${java.bootstrap.classes}</lib>
<lib>${java.cryptographic.extension.classes}</lib>
<lib>${java.secure.socket.extension.classes}</lib-->
</libs>
</configuration>
<dependencies>
<dependency>
<groupId>net.sf.proguard</groupId>
<artifactId>proguard-base</artifactId>
<version>4.10</version>
<scope>runtime</scope>
</dependency>
</dependencies>
</plugin>

I had similar problem, however it could find the references mentioned in the plugin's configuration dependencies section.
However, if I tried to use the proguard-base-4.10 the proguard-maven-plugin (with com.pyx4me groupId) still used the proguard-4.3.jar (you can see it in the maven output in the console); looks like the plugin is only working with a "proguard" artifact, not a "proguard-base".
So I configured the dependencies section to look like:
<dependency>
<groupId>net.sf.proguard</groupId>
<artifactId>proguard</artifactId>
<version>4.10</version>
<scope>runtime</scope>
</dependency>
but this one is not available in the central maven repo (the latest version is 4.4).
What I did was to download the proguard-4.10 manually from proguard download section and install the proguard.jar in the local maven repository under the version 4.10 - and now everything works fine.

There is a newer version of that plugin at: https://github.com/wvengen/proguard-maven-plugin