Develop Reference

How to format code according to google java format

Current state:
I have a project which is build with: Java 1.8.161, Maven 3.3.9, SpringBoot 2.0.1, tools: Jenkins and GitLab. I would like to use google java format as a standard for whole team.
My investigation / solution:
During the investigation I found solution, which sounds really easy. Just update pom file with:
<build>
<plugins>
<plugin>
<groupId>com.coveo</groupId>
<artifactId>fmt-maven-plugin</artifactId>
<version>2.5.0</version>
<executions>
<execution>
<goals>
<goal>format</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
And it works. If I run compile, package, verify, install or deploy Maven lifecycle the code is formatted.
Question:
How can I run this after i.e. each commit for all team members without any extra steps in their IDEA? Because right now, I need to run Maven before each commit. But during the run of an application it is not necessary, so the team can avoid it.. Which of course will lead to problems with history in git.

You can let pre-commit hook trigger formatter for files staged for commit.
git-code-format-maven-plugin uses google-java-format formatter and can install client-side pre-commit git hook during compile phase. It requires Maven 3.5.x, which should be enforced.
<build>
<plugins>
<plugin>
<groupId>com.cosium.code</groupId>
<artifactId>git-code-format-maven-plugin</artifactId>
<version>VERSION</version>
<executions>
<execution>
<goals>
<goal>install-hooks</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<artifactId>maven-enforcer-plugin</artifactId>
<version>VERSION</version>
<executions>
<execution>
<goals>
<goal>enforce</goal>
</goals>
<configuration>
<rules>
<requireMavenVersion>
<version>[3.5.4,)</version>
</requireMavenVersion>
</rules>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
Point to standalone Maven in IDE as git-code-format-maven-plugin does not play along nicely with embedded Maven.
mvn compile to get hook installed. For IDEA, that's it.
As git-code-format-maven-plugin only formats changed files (which is good), it is probably good to format whole project upfront once (mvn git-code-format:format-code -Dgcf.globPattern=**/*).
Workaround for Eclipse
Because of a bug in EGit, which sometimes ignores Git hooks completely, developers using Eclipse on Windows should have Cygwin in PATH. An empty cygpath.exe will do. Run 'Command Prompt' as a administrator and execute C:\>echo "" > /"Program Files"/Git/bin/cygpath.exe (kudos to hook is not working eclipse egit client).
Reboot.
A note on java import statements ordering
Optimise imports or reformat in IDE or reformat with plugins, can lead to changes in imports ordering. A nasty surprise if an older version of git-code-format-maven-plugin is being used together with fmt-maven-plugin (to format or validate code later in CI, for example).
git-code-format-maven-plugin will sort imports (since version 1.20)
fmt-maven-plugin will always sort imports
googleformatter-maven-plugin can optionally sort imports (not per default)

In order to run this formatter after each developer commit, you will have to first have a Jenkins commit hook in place, that will trigger a Jenkins build. One of the phases of the build, should execute the fmt-maven-plugin's (or any others) check functionality in order to ensure that the code is properly formatted.
Adding a webhook
First thing to do is add a webhook that will trigger a Jenkins build after every commit in your git repository. You can find how to do this here. For Gitlab specific instructions, this post from medium may be helpful.
Executing the check
This can be done by executing the check goal on the fmt-maven-plugin
Maven acceps either <plugin-prefix>:<goal> or <plugin-group-id>:<plugin-artifact-id>[:<plugin-version>]:<goal> as a means of calling a plugin goal, so for your specific problem, you can run:
mvn fmt:check
That being said, you will have to add a Jenkins build step, that will run the mentioned command. Step 5 from this tutorial shows you how to add a build step.
Hope that this actually helps :D

I need to run Maven before each commit
You do not need to run multiple maven goals. For eg no need to run maven install for the formatting to take place. A simple maven compile will formate the classes.

Java web app hello world

I have a couple of questions.
I'm trying to learn how to make web apps with Java (I'm coming from C#). The project which I'm going to work on is using Spring MVC.
Now all the tutorials of Spring MVC / Java want me to use Maven. I'm also using Eclipse.
My problem is that every time I try to run a project downloaded from some tutorial like these:
http://tech-read.com/2011/10/31/spring-3-mvc-annotations/
http://www.mkyong.com/spring3/spring-3-mvc-hello-world-example/
I can't run the project. it tells me that the project has no main and then tries to find a class, nothing very clear...
I've also watched youtube videos about it, and some guy was using Jetty to launch the website. (video link : http://www.youtube.com/watch?v=uv9tXFrTLtI)
So my question is:
If I have Eclipse, Oracle JDK 1.7, Spring Tool Suite 3, Maven + m2e - Maven Integration for Eclipse, Spring IDE blah blah plugin, should I be able to run a website from a simple Hello World project? If so, Is there something specific I have to tell Maven / Eclipse to launch my things?

You need to run it in a server context.
To do this you need to install a java web server, like svz said. Tomcat is the one I use.
Spring Source Toolkit (STS) comes with this set up out of the box.
Spring is confusing enough to learn, I would suggest using this IDE until you get the hang of it, then you can experiment with better (different?) web servers.
Try right clicking on your project and running it on a server.
It should be set up to do it for you out of the box.
You can also install it as a plugin to eclipse, or install tomcat manually and drop your war files into the app directory.

You could use jetty. Add the jetty plugin in your pom like this :
<build>
<finalName>spring-mvc-webapp</finalName>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.7</source>
<target>1.7</target>
</configuration>
</plugin>
<plugin>
<groupId>org.mortbay.jetty</groupId>
<artifactId>maven-jetty-plugin</artifactId>
<version>6.0.1</version>
<configuration>
<scanIntervalSeconds>10</scanIntervalSeconds>
</configuration>
</plugin>
</plugins>
</build>
Execute mvn jetty:run
Connect to URL : http://localhost:8080/spring-mvc-webapp/

Compiling Default Vaadin Widgets of a Maven Project

I apologize if this question has been answered elsewhere, but I couldn't seem to find an the exact response that I've been looking for. So I'm in the middle of altering a web application that once relied heavily on the jQuery UI to use Vaadin, instead. To make it easy for me to understand, I created a new Maven project and altered the pom.xml to include the following plugins:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.6</source>
<target>1.6</target>
</configuration>
<version>2.3.2</version>
</plugin>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>tomcat-maven-plugin</artifactId>
<configuration>
<server>local_tomcat</server>
<path>/illuminate</path>
<url>http://127.0.0.1:8080/manager/text</url>
</configuration>
<version>1.1</version>
</plugin>
Now, I can manage to build and deploy my very simple application to Tomcat just fine, but when I attempt to go to it, I get the following error:
In order to get a better understanding of how to set up this kind of project, I checked out a recent applicaiton that uses Vaadin with Maven from our repository called "Tag." Looking at the error, it looks as though it's trying to find a JavaScript file nocache.js in a directory that starts off accurate (Illuminate is my current application), but then branches off into this other project that has no link to my current one. I'm not sure if the browser has something to do with this or not, but I learned that it might have something to do with the widgets of my project having not been compiled yet. I've noticed that there are some other plugins that will do this, but these two are the only ones that this other project, Tag, makes use of, so I figured mine should work just fine. I have also been trying to follow the step-by-step process to make a simple "Hello World" like program from the Vaadin Tutorial. So... Anyone know what I am missing? If it's the compilation of the widgets (I only wish to use the defaults, I suppose), do I NEED those other plugins?

Thats problem of tomcat not deploying VAADIN dir content.
see below blog
http://fmucar.wordpress.com/2011/04/20/vaadin-maven2-eclipse/

Maven and GWT (and Eclipse) - Does it really work?

Over the past few days I have been trying to create/run a project in Eclipse using the gwt-maven-plugin and keep running into roadblocks (see some of my previous questions). I like to use Maven to do my builds, but I'm at the point where I'm thinking of going the Ant build route because of the complications of using Maven.
Does anyone out there have it configured/working well? Is it just me or is this harder than it should be?

After much frustration trying to get things to play nicely together, this is the setup I have that "works" for me. "Works" meaning that I can create, run and debug a GWT project with tweaks, but it isn't the most elegant solution.
Create Project
Much of the steps are the same as Pascal's answer in this post: Maven GWT 2.0 and Eclipse. I'll list mine out to be clear.
In Eclipse (Helios) with m2eclipse and GWT Eclipse plugins installed:
Create a new Maven project using the gwt-maven-plugin archetype
Modify the pom.xml:
set <gwt.version property> to 2.0.4
(needs to be same as GWT Eclipse
Plugin version)
set <maven.compiler.source> and
<maven.compiler.target> properties to
1.6
remove <goal>generateAsync</goal>
from gwt-maven-plugin <plugin> config
add maven-war-plugin to pom.xml
maven-war-plugin example:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-war-plugin</artifactId>
<version>2.0.2</version>
<configuration>
<warSourceDirectory>war</warSourceDirectory>
<webXml>src/main/webapp/WEB-INF/web.xml</webXml>
</configuration>
</plugin>
Update project Properties:
Google -> Web Toolkit, check the "Use Google Web Toolkit" box, and ensure "Use default SDK (GWT-2.0.4) is selected.
Run Maven "gwt:eclipse" goal on project (sets up environment and launch config)
Copy *.launch file to workspace.metadata.plugins\org.eclipse.debug.core.launches
Restart Eclipse
Compile/Run Project
I created a Run Configuration that does mvn clean compile gwt:run. The gwt:run is necessary to copy the resources and lib jars into the war directory. However, it does not copy the web.xml from src/main/webapp/WEB-INF into war/WEB-INF/. So, I have to manually copy that file.
If I want to run my application, the above step is sufficient. However, if I want to debug the application, I launch it by choosing the Google "Web Application" configuration from Debug Configurations that was created when the .launch file was copied previously. This configuration allows for debugging (breakpoints etc.) without any other config or need for remote debugging.

It is harder then it should be, however it is possible. All hints posted here can do the trick. However you can still have classloading issues. I decided to switch to GWT 2.1 and use new abilities of JettyLauncher. You can create own jetty launcher like this:
public class MyJettyLauncher extends com.google.gwt.dev.shell.jetty.JettyLauncher {
#Override
protected WebAppContext createWebAppContext(TreeLogger logger, File appRootDir) {
return new WebAppContext(appRootDir.getAbsolutePath(), "/");
}
}
And then add -server MyJettyLauncher option to your gwt launcher configuration. With such configuration all the libraries are managed by m2eclipse (you can even remove GWT SDK from classpath) and there is no need to copy anything to WEB-INF/lib (you can remove gwt-servlet.jar which could be already there).
Ready launcher is here in tadedon library:
http://code.google.com/p/tadedon/source/browse/tadedon-gwt-dev/src/main/java/com/xemantic/tadedon/gwt/dev/JettyLauncher.java

Yes, in 2016 it does, quite nicely indeed. :)
I launch Tomcat from within Eclipse, I launch GWT codeserver (SuperDev mode) from Eclipse, I launch Chrome from Eclipse.
You will find quite recent and very valuable set-up tutorials on Brandon Donnelson's YouTube channel: https://www.youtube.com/user/branflake2267/videos
What is essential for me is Eclipse debugger for GWT SuperDevMode: https://sdbg.github.io/
I prefer to have my project "mavenized", and there is lot of Maven archetypes also provided by Brandon: https://github.com/branflake2267/Archetypes/tree/master/archetypes
The official starting point (not just) for downloading the GPE plugin (not to confuse with above mentioned debugger plugin) is on GwtProject.com: http://www.gwtproject.org/download.html
For me personally GPE itself has become rather optional "convenience" component. (Yes, refactoring and auto-completion are nice to have, but that's all it is needed for. :)
It is not a one-click solution, and I prefer it like that, as those tend to be black-boxes prone to breaking.
And BTW make sure to take a look at GWT Material: http://gwtmaterialdesign.github.io/gwt-material-demo/
(Currently playing with 2.8-beta1.)

For Eclipse I use: m2eclipse plugin (1.0). It works well with one or two minor things. Also download the m2eclipse-extras plugin to add SVN functionality AND Maven (or CVS if you prefer).
When you download then your project it reads the pom.xml and [re]creates the Eclipse configuration files like the mvn eclipse:eclipse command.
For GWT... I've used it too. It's a pretty twiked configuration but it works. I use GWT 2.0.3, the maven-gwt-plugin uses the dependencies to work (no ref to GWT SDK) and it can debug from Eclipse which is simply great.
You have to compile to a war directory (not the target/classes standard). But the details are in my work, so let me see it tomorrow and complete this answer :) Don't give up. It's a great thing to have GWT+Eclipse+Maven.
Edit: part of my configuration
<build>...
<outputDirectory>war/WEB-INF/classes</outputDirectory>
...
</build>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>gwt-maven-plugin</artifactId>
<version>1.2</version>
<configuration>
<gwtVersion>${gwt.version}</gwtVersion> <!-- para forzar que use el de maven y no el SDK instalado -->
<disableCastChecking>true</disableCastChecking>
<disableClassMetadata>true</disableClassMetadata>
<runTarget>/subscriber/listSubscribers.htm</runTarget>
<webappDirectory>${basedir}/war</webappDirectory>
<soyc>true</soyc>
</configuration>
<executions>
<execution>
<goals>
<goal>compile</goal>
<goal>test</goal>
</goals>
</execution>
</executions>
</plugin>
<!-- dont know/remember if the jetty inside the gwt uses this... but it doesnt hurt-->
<plugin>
<groupId>org.mortbay.jetty</groupId>
<artifactId>maven-jetty-plugin</artifactId>
<version>6.1.14</version>
<configuration>
<webAppConfig>
<contextPath>/magazine</contextPath>
<baseResource implementation="org.mortbay.resource.ResourceCollection">
<resourcesAsCSV>
${basedir}/src/main/webapp,
${basedir}/war
</resourcesAsCSV>
</baseResource>
</webAppConfig>
<connectors>
<connector implementation="org.mortbay.jetty.nio.SelectChannelConnector">
<port>8888</port>
<maxIdleTime>60000</maxIdleTime>
</connector>
</connectors>
<scanIntervalSeconds>3</scanIntervalSeconds>
<scanTargets>
<scanTarget>${basedir}/war</scanTarget>
</scanTargets>
</configuration>
</plugin>
AND
For debugging I create two tasks:
1) maven build inside eclipse that runs two goals: war:exploded gwt:debug
The first one copies all the resources into war directory for gwt debug to use them.
Next the gwt is ready.
Maybe you need to execute gwt:compile for the first time
2) a Java Remote Application debug configuration, with your project selected.
You run this configuration when the gwt:debug is "listening at port 8000"
AND: this is in a parent pom.xml (sorry I'll edit this post later :)
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-war-plugin</artifactId>
<version>2.1-alpha-2</version>
<configuration>
<warSourceDirectory>${basedir}/src/main/webapp</warSourceDirectory>
<webappDirectory>${basedir}/war</webappDirectory>
<warName>${artifactId}</warName>
</configuration>
</plugin>

helios wrote good explanation. But it's not actual at the moment. So I advice you to try my modern example of EAR application running on GlassFish and with full debug support.

Preprocessing source code as a part of a maven build

I have a lot of Java source code that requires custom pre-processing. I'd like rid of it but that's not feasible right now so I'm stuck with it. Given that I have an unfortunate problem that shouldn't have existed in the first place, how do I solve it using maven?
(For the full story, I'm replacing a python-based build system with a maven one, so one improvement at a time please. Fixing the non-standard source code is harder, and will come later.)
Is it possible using any existing Maven plugins to actually alter the source files during compile time? (Obviously leaving the original, unprocessed code alone)
To be clear, by preprocessing I mean preprocessing in the same sense as antenna or a C compiler would preprocess the code, and by custom I mean that it's completely proprietary and looks nothing at all like C or antenna preprocessing.

There is a Java preprocessor with support of MAVEN: java-comment-preprocessor

This is something that is very doable and I've done something very similar in the past.
An example from a project of mine, where I used the antrun plug-in to execute an external program to process sources:
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-antrun-plugin</artifactId>
<executions>
<execution>
<id>process-sources</id>
<phase>process-sources</phase>
<configuration>
<tasks>
<!-- Put the code to run the program here -->
</tasks>
</configuration>
<goals>
<goal>run</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
Note the tag where I indicate the phase where this is run. Documentation for the lifecycles in Maven is here. Another option is to actually write your own Maven plug-in that does this. It's a little more complex, but is also doable. You will still configure it similarly to what I have documented here.

Maven plugins can hook into the build process at pre-compile time yes, as for whether or not any existing ones will help I have no idea.
I wrote a maven plugin a couple of years ago as part of a university project though, and while the documentation was a bit lacking at the time, it wasn't too complicated. So you may look into rolling your own, there should be plenty of open source projects you can rip ideas or code from (ours was BSD-licenced for instance...)