In Eclipse i forgot how to add a specific jar from m2 repo in the case that we have a maven project without the m2e Plugin in Eclipse
From the command line, run mvn eclipse:eclipse to generate Eclipse metadata for your project, then restart Eclipse and, if needed, reimport your projects.
You'll need to repeat that for every dependency change. In the long run, you're probably better off using m2e.
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I have integrated m2e plugin.When i change the java file .It invokes building workspace. Is this is eclipse build or maven build.
And what exactly the difference between Eclipse clean and mvn clean ?
The m2e plugin injects the Maven classpath into the Eclipse project plus it disables the default Eclipse resource copying so Maven can do it's magic (the Maven resource copy step can filter/transform resources).
The actual build for Java files uses the Eclipse compiler with the classpath supplied from m2e.
Clean: Unless you have configured something special, Eclipse clean will delete target/classes and target/test-classes while mvn clean will delete the whole target/ folder.
Also, Eclipse will build the project again right after clean. For Maven, you need to issue another command (mvn compile or mvn install).
Check your .project file.
Do you have something like org.eclipse.m2e.core.maven2Builder there? Then it's Maven build executed by Eclipse via m2e.
The exact difference between "Eclipse clean" and mvn clean...
mvn clean executes Maven clean phase, as it is configured (or inherited) in the pom.xml.
For Eclipse clean, see this question:
Function of Project > Clean in Eclipse
Can any one explain how to add Maven dependency JAR i.e. build path libraries? To be very specific how to include JAR file mentioned in pom.xml to Java build path? Maven dependencies - unable to see jars over here.
Don't have a option to update Maven dependencies. Also executed the script mvn eclipse:eclipse, seen on StackOverflow.
Generally, you should not have any need to deal with such a task manually. Here is the correct procedure for importing of maven project to your Eclipse IDE:
Make sure you have m2eclipse plugin installed (Maven support for Eclipse). As far I remember it is included to Eclipse IDE for JEE developers by default.
Checkout your maven project to any directory
From this directory (root pom.xml is located in), run: mvn eclipse:eclipse
Go to Eclipse, File -> Import, select "Existing maven project"
Select directory where your root pom.xml is located, Eclipse should find all maven modules.
Optional: if eclipse will tell you that it can't recognize some maven plugins - ignore this, just continue.
If you follow this instruction, IDE will create all maven modules as eclipse projects and you will have an option to update maven dependencies and also willsee all of them rigth in IDE.
What is the difference between running a maven build on a maven project
mvn install
then importing the module in eclipse (Import > Existing Maven Projects) as a maven artifact versus running
mvn install eclipse:eclipse
and importing the maven project as a regular project (Import > Existing Projects into Workspace)?
The second option seems faster within eclipse (mvn install eclipse:eclipse) but I'm not sure why.
When you import an existing Maven project, it is done by m2e, the official Eclipse Maven plugin (when I say official I mean it is in the Eclipse incubation process). It offers more features and can be more convenient to use in my experience
When you do it by eclipse:eclipse, it is done by a Maven Eclipse mojo which creates a simple Java project. The problem is that you have to re-do this again every time you change your pom.xml. With m2e, this is usually done automatically.
I've created a multi-module project using Indigo with m2e 1.0. One of the child modules has a dependency on the other. It all builds correctly under maven.
Eclipse, however, can't find any of the classes that this module uses from the dependency .jar. The project properties shows the artifact under Maven Dependencies, but it does not show the actual .jar file itself.
I added the dependency with the Maven menu for this project.
The .project and .classpath got generated automagically at some point. I did not have to run mvn eclipse:eclipse or mvn eclipse:m2e (or whatever the goal is for m2e). The .classpath doesn't have the dependent .jar in it, but it does have org.eclipse.m2e.MAVEN2_CLASSPATH_CONTAINER.
I've tried all the options under the Maven menu (update dependencies, update configuration) and refreshing the project. I've closed and re-opened Eclipse. It still shows errors.
This makes Eclipse worthless as a Java editor in multi-module projects. I could manually add the dependency .jar in the .classpath, but this defeats the purpose of integration Eclipse and Maven with m2e.
Is there any solution for this in Eclipse?
Thanks.
The answer turned out to be the last answer to this question given by Jody Box. It's pretty bizzare that in order for Eclipse to resolve dependencies from another project in the Workspace that you have to uncheck the "Resolve dependencies from Workspace projects" checkbox.
I know mvn can be convoluted but this checkbox is doing the opposite of what it says.
I've created a new project in maven like this:
mvn archetype:generate -DgroupId=com.mycompany.app -DartifactId=my-app -DarchetypeArtifactId=maven-archetype-quickstart -DinteractiveMode=false
After that I use: mvn eclipse:eclipse
The problem is that when I add the project to my IDE, eclipse indicates errors. When I run it I get classNotFound for JUnit. In project properties I see that junit is added to build path
In project properties I see: M2_REPO/junit/junit/3.8.1/junit-3.8.1.jar
But I cant use for example: import junit.framework.Test;
Why is that? To be honest, I have some major problems with dependency in maven and eclipse. Maven adds them correctly but eclipse doesn't see it correctly. It's not only the junit. What should I check/set?
Should I install some plugin to eclipse for maven support ?
EDIT
I thought again about everything. Of course the problem was small. M2_REPO was not recognize by Eclipse. I've added this variable and set it in od maven directory. It worked like a charm.
You can use the m2eclipse plugin for eclipse
http://m2eclipse.sonatype.org/installing-m2eclipse.html
I don't know if having the plugin would solve your problem, I used to do the command line before I started using m2elcipse, I never had the issue that you described
what version of eclipse are you using?