Why Eclipse clean after mvn clean install - eclipse

I have a interesting observation at my new job at a Major Silicon Valley Company.
This is a mvn/java project.
I am being told to do command-line "mvn clean install" and then go to Eclipse and select Project & then do "Clean" Build.
I am confused as the difference between "mvn clean install" & Eclipse "Clean", I thought since it's the same pom.xml the outcome should be the same. Interstingly my code changes to java classes do not show till I have done both. I was expecting to see changes after command-line "mvn clean install"

Eclipse has own project structure and build routines.
Maven has own project lifecycle.
Maven integrates into Eclipse with m2e plugin. It is some kind of art to relate Maven and Eclipse stages one to one.
Therefore it very easy to fall into situation when some Eclipse command did not doing all what Maven needs and vice versa, just because m2e can not relate all features of Eclipse and Maven 1 to 1.
Simplest advice is to use Eclipse IDE support for code navigation and editing, but use Maven to clean, compile, package and so on. In this case Eclipse's 'Runtime configurations' very helpfull in configuring and executing Maven's commands.
Use 'Alt+F5' to sync project state.

Related

Use Gradle plugin without adding to build.gradle?

In Maven you can do mvn eclipse:eclipse to run the eclipse goal of the maven-eclipse-plugin. Is there a similar way to do this in Gradle? I'd like to run the plugin for my IDE of choice but I want my build script to remain "IDE-agnostic".
I don't want apply plugin 'eclipse' in my build.gradle file but want it to generate the Eclipse files it needs. This way users of IntelliJ won't need to swap it.
Rather than rely on the build tool to configure your IDE (who ever thought that was a good idea is beyond me), set up the IDE to understand and integrate with the build tool. Eclipse is specifically designed to share configuration in such a way that each person who checks out a project from source control gets the project configured correctly with a minimum of manual intervention. Gradle support is much newer and somewhat less mature than Ant or Maven, but it works. See the Buildship project, which allows you to point Eclipse at your existing Gradle-based project and import it as a properly configured Eclipse project, no need for hacks like mvn eclipse:eclipse (which is now deprecated/retired, by the way)

How eclipse maven and ant work together?

I made simple maven project and I opened it with Eclipse. I have installed maven plugin for Eclipse. I'm interested in following:
How Eclipse compiles code when I hit save on my source code (does it use configuration from ant or maven or something else)?
When I run tests from JUnit plugin for Eclipse those Eclipse calls mvn test (I suppose not, but what is then happening exactly)?
Is it possible that maven does the build successfully but Eclipse is
showing errors in code?
The Maven Integration for Eclipse makes it easier to edit POM files, allows you to execute maven builds from within Eclipse and to help with dependency management. It doesn't actually compile your code (unless of course you execute a maven build from within Eclipse). The main help is with the dependency management and writing the .classpath file of your project within Eclipse.
To try and answer your questions:
Eclipse uses its standard mechanism to compile code. With a standard eclipse for java developers your project will have a Java Project nature and Eclipse will then use the Java Development Tools - JDT to compile the code. (Internally this uses an incremental builder to build the code http://help.eclipse.org/juno/index.jsp?topic=%2Forg.eclipse.platform.doc.isv%2Fguide%2FresAdv_builders.htm). What source files it will compile and where it will place the resultant .class files is configured in your project's Java Build Path (which I am guessing the maven plugin may well configure for you)
JUnit support is part of the Java Development Tools as well.
It is possible that maven will successfully build a project outside of Eclipse, but that the same project will show errors within Eclipse. This is usually down to classpath errors (dependencies defined in the project's POM not being added to the classpath in Eclipse). If you are using the maven plugin with eclipse this probably shouldn't happen. If you are not using the maven plugin within eclipse you can execute maven eclipse:eclipse to have maven update the Eclipse .classpath file of the project which should then fix any of these problems.

How to fix error "Updating Maven Project". Unsupported IClasspathEntry kind=4?

I have imported maven project in STS, when I run update update project I receive:
"Updating Maven Project". Unsupported IClasspathEntry kind=4
Is there a workaround for this?
This issue has been fixed in m2e 1.5.0 which is available for Eclipse Kepler (4.3) and Luna (4.4)
Please see https://bugs.eclipse.org/bugs/show_bug.cgi?id=374332#c14
The problem is caused by the fact that STS (the Spring IDE/Eclipse), as well Eclipse and other Eclipse based IDE's, use the m2e(clipse) plugin but that eclipse:eclipse has been probably been run on the project. When m2e encounters a "var" .classpath entry, it throws this error.
The update sites are specified at the following url:
http://eclipse.org/m2e/m2e-downloads.html
If you can't use m2e 1.5.0 for any reason, then :
Disable the maven nature for the project (via the right-click menu)
Run mvn eclipse:clean (while your project is open in STS/eclipse). Depending on the timing, you might need to do a refresh or two on the project before re-enabling the maven nature. You should be able to see that your project has lost it's Maven nature. (The eclipse:clean goal just deletes the .project, .classpath and .settings/ files/directories. You can also just remove those files (again while the project is open) instead of running mvn eclipse:clean.)
Re-enable the maven nature.
(Most of the time, this can be done by right-clicking on the project in question in the package explorer pane, and then choosing 'Configure'-> 'Convert to Maven Project')
Right-click on your project, select Maven -> Remove Maven Nature.
Open you terminal, go to your project folder and do mvn eclipse:clean
Right click on your Project and select “Configure -> Convert into Maven Project”
Now you got “Unsupported IClasspathEntry kind=4 Eclipse Scala” disappear.
Sometimes, even re-importing the Maven project will not work. Updating the project correctly in eclipse is not a deterministic process.
The only 100% fail safe procedure I've found is:
Disable Maven Nature, run mvn eclipse:clean, restart, cross your fingers and Pray 3 times.
If this won't work, delete the project, run mvn eclipse:clean, re-import refresh, pray and use the force.
If this still doesn't work, restart Eclipse, or even better your computer. While waiting for the reboot, you can make a random donation to fix your Karma. Repeat step 2 and don't forget to pray and control your anger. Anger leads to hate. Hate leads to suffering.
Try all the other answers posted in this thread. You might need to try them all for 3 times at least before giving up.
Format your Computer, re-install Eclipse and Maven. No need to pray anymore, all gods hate you anyway
Delete your git project, burn the physical drive that stored the remote repository, and write your project from scratch.
Find a time machine, travel to the past and convince yourself to follow another, non-programming career or at least to avoid Java
Make sure that the version of the m2e(clipse) plugin that you're running is at least 1.1.0
Close maven project - right click "Close Project"
Manualy remove all classpathentry with kind="var" in .classpath file
Open project
or
Remove maven project
Manualy rmeove .classpath
4 Reimport project
Have you tried:
If you have import project into the eclipse 4, please delete it.
In maven consol, run: mvn eclipse:clean
In Eclipse 4: File -> Import -> Maven -> Existing Maven Projects
Seeing all other answers. I found for me a simpler way.
I just removed all lines in the .classpath (editing with eclipse) containing a var and used maven -> update project without an error.
This error is also thrown if the update command is used on a project instrumented for code coverage with Clover.
To resolve in this scenario:
Un-instrument the project folders you wish to update.
Run the maven update then instrument for code coverage again.
I tried Marco's steps but no luck. Instead if you just get the latest m2e plugin from the link he provides and one by one right click on each project -> Maven -> Update Dependencies the error still pops up but the issue is resolved. That is to say the warnings disappear in the Markers view. I encountered this issue after importing some projects into SpringSource Tool Suite (STS). When I returned to my Eclipse Juno installation the warnings were displaying. Seeing that I had m2e 1.1 already installed I tried Marco's steps to no avail. Getting the latest version fixed it however.
I couldn't get mvn eclipse:clean etc to work with Kepler.
However I changed creating and extending variables to just using external jars in my eclipse classpath. This was reflected in no var's in my .classpath.
This corrected the problem. I was able to do a Maven update.
This issue (https://bugs.eclipse.org/394042) is fixed in m2e 1.5.0 which is available for Eclipse Kepler and Luna from this p2 repo :
http://download.eclipse.org/technology/m2e/releases/1.5
If you also use m2e-wtp, you'll need to install m2e-wtp 1.1.0 as well :
http://download.eclipse.org/m2e-wtp/releases/luna/1.1
Upgrading from Kepler to Luna worked for me.
I had just added some components for Java 1.8 support. It seems that they where not as compatible as I would like or that I mixed the wrong ones. It really caused a lot of problems. Trying to update the system reported errors as they couldn't fulfill some dependencies. Maven upgrades didn't work. Tried a lot of things.
So, if there is no reason to avoid the upgrade just add the luna repository to avalilable software sites (Luna http://download.eclipse.org/releases/luna/ ) and "check for updates". It is better to have all the components with the same version and there are some nice new features.
I tried all the steps mentioned here and on similar questions but couldn't solve this problem. I could neither solve problem nor update my m2eclipse. So I installed Eclipse Luna and it solved my problem... though it mean that I had to spend about 45 min to configure all the environment in my workspace.
Try
mvn clean install eclipse:eclipse -Dwtpversion=2.0 command on DOS command prompt.
Suggesting you because , It worked for me!!
I'm using Eclipse 4.3.2 (Kepler) with M2E 1.4.x and felt over this problem several times!
In my case the "mvn eclipse:eclipse" command also generates Checkstyle, PMD and Findbugs configuration so "mvn eclipse:clean" does not help me because it drops all those config files again.
The best solution for me was to delete all ".classpath" files:
find . -name ".classpath" -delete
and import the project into eclipse afterwards.
Before importing the project, it should be converted into eclipse project
mvn eclipse: eclipse
Then i found the following error.
An internal error occurred during: "Importing Maven projects".Unsupported IClasspathEntry kind=4
Where is the value kind = "var" that M2E does not recognize and therefore throws the error.
Now type this.
mvn eclipse: clean
Now refresh the project in eclipse or re-import.

How to combine mvn clean and mvn install into a single task?

I'm following the Scala, Eclipse and Maven Integration tutorial.
It is really useful.
But there is one thing that seems annoying to me:
I always need to run two commands from the Eclipse Run as menu:
Maven clean
Maven install
Is there any way to configure Scala and Maven plugins for Eclipse, to make it possible to run both tasks as a single command from the Eclipse menu?
For example:
Maven clean install
like in the following Eclipse non-Scala configuration.
Choose the option Maven build..., and type clean install in the Goals text box.

Question on "Converting Maven project of Mahout into Eclipse project"

While installing the open-source software like Mahout, I read some notes like
Convert Maven project of Mahout into Eclipse project
What does this mean? What's the difference between a Maven project and Eclipse project?
Install Maven if you haven't already done it.
Enter the command prompt or a shell and navigate to the directory where the Mahout is located (there's a pom.xml file). Type the command:
mvn eclipse:eclipse
which will create project files for Eclipse and open the project in Eclipse.
No conversion is needed. Eclipse supports Maven projects, and vice-versa.
Difference between these two projects yield from the difference of the tools. Eclipse is an IDE and Maven is a build tool. In fact, IDE is a superset of a build tool. That's why Eclipse may use Maven for building. Common properties between the projects relate to how the build is being done and Eclipse has a set of properties aimed to persist the state between programming sessions.