We have a system which runs on Java 6 and uses Ant. I want to migrate the system to Java 13 and Maven.
What are the things that I need to consider when performing this migration? I understand that some third party libraries may cause issues but I'm hoping that all the Java libraries will work smoothly as before.
What is the easiest way to follow in doing this? Is there a plugin in an IDE which can perform the Ant to Maven migration easily?
Thanks in advance.
First migration is a manual process
Change the directory to follow Maven conventions
Create one/more pom files which fill your needs. Do you have multiple modules?
Try to build with maven
Are you within a company? Yes start with a repository manager
Make configuration (settings.xml).
Start to build with JDK 8 first (expect issues with libraries)
Try to build with JDK 11 (expect some issue with libraries)
Finally JDK 13
Related
As of Java 11 it is necessary to get JAXB from a separate library, not from the JDK. There are plenty of tutorials on the Web showing how to do that, but they all use Maven. The project I need to fix is an Eclipse RCP application. There does not seem to be an easy to make that work with Maven, as Maven essentially takes over most of what Eclipse would do but doesn't have RCP development capabilities.
Sooner or later Maven gets the required libraries. I would like to find another way to get and use whatever libraries are needed, just without using Maven. It should be possible. I just haven't found it.
Thanks.
I did what I wanted by downloading the needed JARs from https://mvnrepository.com/.
I am a total beginner at maven, I have read about it online but I am still confused how it can be used. I have eclipse Oxygen version installed and when I open projects I can see maven project option is already there. I was even able to create a maven project using YouTube tutorial. But now then I saw popular plugin called m2eclipse but I am not able to comprehend why is it actually used; when my application ran without it.
I am learning maven to get started with spring boot but I am finding it really overwhelming where to begin with, and many of the tutorial sites state to download maven (But maven already comes along with eclipse?)
Please explain.
Apache Maven is a build tool - a tool for compiling the source code of a project into a program that you can run (for example a jar file, or a war file that can be deployed on a Java EE application server). Besides automating all the tasks for building a project, it also gives you a standard way to organize your project and to keep track of dependencies (libraries that your project needs).
Why do you need such a tool?
When you write a small program that consists of one, or maybe a few source files, it's easy enough to compile it by hand on the command line, by directly using the Java compiler javac that comes with the JDK.
But when your project becomes more complex, and you have hundreds or even thousands of source files in multiple modules, it becomes really hard to keep track of everything and cumbersome to compile the files using javac. If your program needs libraries, it becomes even more complex, because you have to make sure that all the libraries are on the classpath, and some libraries need other libraries, which also have to be on the classpath.
A tool such as Maven helps you to compile all the source files in the right order and to keep track of all the libraries. Maven can automatically download libraries from the web and add them to your project, and downloading everything and building the whole project can be done with one simple command such as mvn clean package.
Spring Boot is part of the Spring Framework, which is a huge framework with tons of useful functionality for developing projects in Java. A Spring Boot project typically needs dozens of libraries, and it would be very hard to use if you'd have to keep track of all those libraries by hand - so that's why it uses Maven to manage all of this for you.
A Maven project is configured using a file named pom.xml - in that file, you describe your project and you put a list of libraries that your project needs. When you build your project, Maven will read the pom.xml file and figure out automatically what source files need to be compiled, and what libraries need to be downloaded.
m2eclipse comes preinstalled in Eclipse (at least when selecting "Eclipse for Java developers" or "Eclipse for Java EE developer"), thats why you were able to use Maven by default.
Still you probably want a command line Maven, because that's most likely how it will eventually run on the CI server, sometimes Eclipse Maven installation can produce different result than the command line install.
Now that Bazel (http://bazel.io/) has been opensourced, is there an incremental process by which I can gradually migrate (a large repository) from Maven to Bazel?
I work on Bazel. No, as far as we know there is no such process. I wish.
We have been running some migrations from other build systems to Bazel; the evidence isn't conclusive, but it's difficult to even envision how an incremental process would look like. There are some scenarios where we can envision one build system generating configuration files for another (like gyp), but then you still need to switch wholesale.
In the two years since Ulf responded, there's been a few efforts to assist with maven to bazel migration. In particular, the Bazel team is creating a tool to assist with this: https://github.com/bazelbuild/migration-tooling
The tool generates expansive WORKSPACE files from a set of pom files or maven coordinates. In the ideal case, you can pass the path to your maven project, and then it will generate a bzl file you can load into the WORKSPACE file.
More commentary on how to manage external dependencies can be found here: https://bazel.build/versions/master/docs/external.html
And another update (2018)...
There is a dedicated guide on migrating from Maven build tool to Bazel.
And on a general note, it’s best to have both build tools running in parallel until you have fully migrated your development team, CI system, and any other relevant integrations. You can run Maven and Bazel in the same repository.
https://docs.bazel.build/versions/master/migrate-maven.html
September 2019 update
Wix published a tool called Exodus to automatically migrate your Maven project to Bazel.
Additionally, rules_jvm_external has support for managing transitive Maven artifact dependencies.
May 2018 update
Here's another update using Jadep, a BUILD file generator for your Java projects.
There's a tutorial by the author who migrated google-java-format to Bazel: https://github.com/cgrushko/text/blob/master/migrating-gjf-to-bazel.md
I am trying to evaluate Gradle as next-gen build tool for some of my future projects.
Steps I've done so far:
I have Java 7 installed on my machine.
Installed Gradle 2.0
Installed Spring Tool Suite 3.6.1, went to dashboard and added support for
Gradle and installed also Groovy-Eclipse package.
Now when I start Gradle projects from scratch or I clone some of the projects from github,
I am not able to get context sensitive help, like Ctrl + Space to autocomplete stuff in
build.gradle file.
I was reading a lot of documentation on net about this, and couldn't find proper answer, so if someone can give me some idea is it working?
Previously I was using Maven, and m2-eclipse, so when I type in pom.xml I am able to do Ctrl + Space which prevents me to make typo mistakes.
NOTE: Just please note that I've enabled Gradle DSL support for my Gradle projects.
Thank You
Gradle's build language is much more dynamic, extensible, and powerful than a Maven POM, and hence it's much harder to develop full IDE support for it. Recent versions of the Eclipse Gradle Plugin have limited editing support, and work is underway to take it to the next level. IntelliJ 14 is already further along, but expect to see further improvements there as well.
I have a massive Java 6 migration planned for Maven projects that are currently using JDK4 and JDK5.
In doing so, i'd like to script as much as possible. One thing I'd like to script is to replace all Maven references to a JDK4 or JDK5 to JDK6.
The question is, what are all the ways a Maven file can reference JDK?
Here are the ones I know of, listed as XPath's:
//plugin/artifactId[.='maven-compiler-plugin']
//maven.compiler.source
//maven.compiler.target
EDIT: Found another one
/project/profiles/profile/activation/jdk
EDIT: User added one
The aspectj-maven-plugin has source and target configuration.
Am I missing any?