I am using Intellij IDEA 2021.3.1 Community edition on Linux for one of my Maven project. In the pom.xml file, there is a dependency with system scope having version 3.0-20211116.183306-362 as mentioned below:
<dependency>
<groupId>com.wd.xml</groupId>
<artifactId>wdXml</artifactId>
<scope>system</scope>
<systemPath>/home/mylib/wdXml-3.0-20211116.183306-362.jar</systemPath>
<version>3.0-20211116.183306-362</version>
</dependency>
The pom.xml does not have any issue, and mvn package command runs fine. However, the editor shows compilation errors in the Java class using this dependency.
Upon hours of digging, I found that in the 'Project Dependencies View' Intellij lists this dependency as com.wd.xml:wdXml:3.0-SNAPSHOT instead of com.wd.xml:wdXml:3.0-20211116.183306-362.
UPDATE
I believe it is because of this Maven convention
version if you distribute it, then you can choose any typical version with numbers and dots (1.0, 1.1, 1.0.1, ...). Don't use dates as they are usually associated with SNAPSHOT (nightly) builds. If it's a third party artifact, you have to use their version number whatever it is, and as strange as it can look. For example,
2.0, 2.0.1, 1.3.1
How do I resolve this? Is there any setting in the IDE that can be tweaked.
I wonder when I did not specify a plugin version in some module's pom.xml like in:
<build>
...
<plugin>
<groudId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.8.0</version>
</plugin>
...
</build>
What is the default plugin version used when I run "mvn compile"?
I have tried it and see actually it is using maven-compiler-plugin version 3.1 with above plugin element commented, my Maven version is 3.6.3.
I have spent 1 hour to google through Maven's documentation and related posts, but not find exact answer. I really like to know how that version is being decided?
The magic is not happening in the super pom, but in the so called bindings descriptor as available at https://github.com/apache/maven/blob/master/maven-core/src/main/resources/META-INF/plexus/default-bindings.xml.
However, they are moving to the matching packaging plugin, for example for the maven-jar-plugin it is located at https://github.com/apache/maven-jar-plugin/blob/master/src/main/filtered-resources/META-INF/plexus/components.xml
These versions haven't been updated, because it would be weird if 2 users with different Maven versions have different results (e.g. one has a broken build, the other not). Hence it is better to specify the plugin versions in the pom, don't rely of the defaults provided by Maven.
In the end it is all described at https://maven.apache.org/guides/introduction/introduction-to-the-lifecycle.html
It is impossible for maven to work without defining versions of the
artifacts , so somewhere it must be mentioned, lets dig in part by
part.
All pom.xmls are logically inherit from the super POM. You can always see what your "real" pom.xml looks like by typing:
mvn help:effective-pom
The resulting pom.xml that is printed is a combination of the super POM, your pom.xml, and any parent POMs in the mix as well.
Note from Maven 3 the super POM does not contain any of the (default lifecycle) plugins versions but earlier till Maven 2 it used to have.
The Maven 3 super POM is provided by the org.apache.maven.model.superpom.DefaultSuperPomProvider class https://github.com/apache/maven/blob/bce33aa2662a51d18cb00347cf2fb174dc195fb1/maven-model-builder/src/main/java/org/apache/maven/model/superpom/DefaultSuperPomProvider.java#L56-L85
The resource it loads can be found here: https://github.com/apache/maven/blob/bce33aa2662a51d18cb00347cf2fb174dc195fb1/maven-model-builder/src/main/resources/org/apache/maven/model/pom-4.0.0.xml#L23-L149
Edit:
As per Maven Coordinates
groupId:artifactId:version are all required fields (although,
groupId and version need not be explicitly defined if they are
inherited from a parent - more on inheritance later). The three fields
act much like an address and timestamp in one. This marks a specific
place in a repository, acting like a coordinate system for Maven
projects:
version: This is the last piece of the naming puzzle. groupId:artifactId denotes a single project but they cannot delineate which incarnation of that project we are talking about. Do we want the junit:junit of 2018 (version 4.12), or of 2007 (version 3.8.2)? In short: code changes, those changes should be versioned, and this element keeps those versions in line. It is also used within an artifact's repository to separate versions from each other. my-project version 1.0 files live in the directory structure $M2_REPO/org/codehaus/mojo/my-project/1.0.
In Maven, dependencies are usually set up like this:
<dependency>
<groupId>wonderful-inc</groupId>
<artifactId>dream-library</artifactId>
<version>1.2.3</version>
</dependency>
Now, if you are working with libraries that have frequent releases, constantly updating the <version> tag can be somewhat annoying. Is there any way to tell Maven to always use the latest available version (from the repository)?
NOTE:
The mentioned LATEST and RELEASE metaversions have been dropped for plugin dependencies in Maven 3 "for the sake of reproducible builds", over 6 years ago.
(They still work perfectly fine for regular dependencies.)
For plugin dependencies please refer to this Maven 3 compliant solution.
If you always want to use the newest version, Maven has two keywords you can use as an alternative to version ranges. You should use these options with care as you are no longer in control of the plugins/dependencies you are using.
When you depend on a plugin or a dependency, you can use the a version value of LATEST or RELEASE. LATEST refers to the latest released or snapshot version of a particular artifact, the most recently deployed artifact in a particular repository. RELEASE refers to the last non-snapshot release in the repository. In general, it is not a best practice to design software which depends on a non-specific version of an artifact. If you are developing software, you might want to use RELEASE or LATEST as a convenience so that you don't have to update version numbers when a new release of a third-party library is released. When you release software, you should always make sure that your project depends on specific versions to reduce the chances of your build or your project being affected by a software release not under your control. Use LATEST and RELEASE with caution, if at all.
See the POM Syntax section of the Maven book for more details. Or see this doc on Dependency Version Ranges, where:
A square bracket ( [ & ] ) means "closed" (inclusive).
A parenthesis ( ( & ) ) means "open" (exclusive).
Here's an example illustrating the various options. In the Maven repository, com.foo:my-foo has the following metadata:
<?xml version="1.0" encoding="UTF-8"?><metadata>
<groupId>com.foo</groupId>
<artifactId>my-foo</artifactId>
<version>2.0.0</version>
<versioning>
<release>1.1.1</release>
<versions>
<version>1.0</version>
<version>1.0.1</version>
<version>1.1</version>
<version>1.1.1</version>
<version>2.0.0</version>
</versions>
<lastUpdated>20090722140000</lastUpdated>
</versioning>
</metadata>
If a dependency on that artifact is required, you have the following options (other version ranges can be specified of course, just showing the relevant ones here):
Declare an exact version (will always resolve to 1.0.1):
<version>[1.0.1]</version>
Declare an explicit version (will always resolve to 1.0.1 unless a collision occurs, when Maven will select a matching version):
<version>1.0.1</version>
Declare a version range for all 1.x (will currently resolve to 1.1.1):
<version>[1.0.0,2.0.0)</version>
Declare an open-ended version range (will resolve to 2.0.0):
<version>[1.0.0,)</version>
Declare the version as LATEST (will resolve to 2.0.0) (removed from maven 3.x)
<version>LATEST</version>
Declare the version as RELEASE (will resolve to 1.1.1) (removed from maven 3.x):
<version>RELEASE</version>
Note that by default your own deployments will update the "latest" entry in the Maven metadata, but to update the "release" entry, you need to activate the "release-profile" from the Maven super POM. You can do this with either "-Prelease-profile" or "-DperformRelease=true"
It's worth emphasising that any approach that allows Maven to pick the dependency versions (LATEST, RELEASE, and version ranges) can leave you open to build time issues, as later versions can have different behaviour (for example the dependency plugin has previously switched a default value from true to false, with confusing results).
It is therefore generally a good idea to define exact versions in releases. As Tim's answer points out, the maven-versions-plugin is a handy tool for updating dependency versions, particularly the versions:use-latest-versions and versions:use-latest-releases goals.
Now I know this topic is old, but reading the question and the OP supplied answer it seems the Maven Versions Plugin might have actually been a better answer to his question:
In particular the following goals could be of use:
versions:use-latest-versions searches the pom for all versions
which have been a newer version and
replaces them with the latest
version.
versions:use-latest-releases searches the pom for all non-SNAPSHOT
versions which have been a newer
release and replaces them with the
latest release version.
versions:update-properties updates properties defined in a
project so that they correspond to
the latest available version of
specific dependencies. This can be
useful if a suite of dependencies
must all be locked to one version.
The following other goals are also provided:
versions:display-dependency-updates scans a project's dependencies and
produces a report of those
dependencies which have newer
versions available.
versions:display-plugin-updates scans a project's plugins and
produces a report of those plugins
which have newer versions available.
versions:update-parent updates the parent section of a project so
that it references the newest
available version. For example, if
you use a corporate root POM, this
goal can be helpful if you need to
ensure you are using the latest
version of the corporate root POM.
versions:update-child-modules updates the parent section of the
child modules of a project so the
version matches the version of the
current project. For example, if you
have an aggregator pom that is also
the parent for the projects that it
aggregates and the children and
parent versions get out of sync, this
mojo can help fix the versions of the
child modules. (Note you may need to
invoke Maven with the -N option in
order to run this goal if your
project is broken so badly that it
cannot build because of the version
mis-match).
versions:lock-snapshots searches the pom for all -SNAPSHOT
versions and replaces them with the
current timestamp version of that
-SNAPSHOT, e.g. -20090327.172306-4
versions:unlock-snapshots searches the pom for all timestamp
locked snapshot versions and replaces
them with -SNAPSHOT.
versions:resolve-ranges finds dependencies using version ranges and
resolves the range to the specific
version being used.
versions:use-releases searches the pom for all -SNAPSHOT versions
which have been released and replaces
them with the corresponding release
version.
versions:use-next-releases searches the pom for all non-SNAPSHOT
versions which have been a newer
release and replaces them with the
next release version.
versions:use-next-versions searches the pom for all versions
which have been a newer version and
replaces them with the next version.
versions:commit removes the pom.xml.versionsBackup files. Forms
one half of the built-in "Poor Man's
SCM".
versions:revert restores the pom.xml files from the
pom.xml.versionsBackup files. Forms
one half of the built-in "Poor Man's
SCM".
Just thought I'd include it for any future reference.
Please take a look at this page (section "Dependency Version Ranges"). What you might want to do is something like
<version>[1.2.3,)</version>
These version ranges are implemented in Maven2.
Unlike others I think there are many reasons why you might always want the latest version. Particularly if you are doing continuous deployment (we sometimes have like 5 releases in a day) and don't want to do a multi-module project.
What I do is make Hudson/Jenkins do the following for every build:
mvn clean versions:use-latest-versions scm:checkin deploy -Dmessage="update versions" -DperformRelease=true
That is I use the versions plugin and scm plugin to update the dependencies and then check it in to source control. Yes I let my CI do SCM checkins (which you have to do anyway for the maven release plugin).
You'll want to setup the versions plugin to only update what you want:
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>versions-maven-plugin</artifactId>
<version>1.2</version>
<configuration>
<includesList>com.snaphop</includesList>
<generateBackupPoms>false</generateBackupPoms>
<allowSnapshots>true</allowSnapshots>
</configuration>
</plugin>
I use the release plugin to do the release which takes care of -SNAPSHOT and validates that there is a release version of -SNAPSHOT (which is important).
If you do what I do you will get the latest version for all snapshot builds and the latest release version for release builds. Your builds will also be reproducible.
Update
I noticed some comments asking some specifics of this workflow. I will say we don't use this method anymore and the big reason why is the maven versions plugin is buggy and in general is inherently flawed.
It is flawed because to run the versions plugin to adjust versions all the existing versions need to exist for the pom to run correctly. That is the versions plugin cannot update to the latest version of anything if it can't find the version referenced in the pom. This is actually rather annoying as we often cleanup old versions for disk space reasons.
Really you need a separate tool from maven to adjust the versions (so you don't depend on the pom file to run correctly). I have written such a tool in the the lowly language that is Bash. The script will update the versions like the version plugin and check the pom back into source control. It also runs like 100x faster than the mvn versions plugin. Unfortunately it isn't written in a manner for public usage but if people are interested I could make it so and put it in a gist or github.
Going back to workflow as some comments asked about that this is what we do:
We have 20 or so projects in their own repositories with their own jenkins jobs
When we release the maven release plugin is used. The workflow of that is covered in the plugin's documentation. The maven release plugin sort of sucks (and I'm being kind) but it does work. One day we plan on replacing this method with something more optimal.
When one of the projects gets released jenkins then runs a special job we will call the update all versions job (how jenkins knows its a release is a complicated manner in part because the maven jenkins release plugin is pretty crappy as well).
The update all versions job knows about all the 20 projects. It is actually an aggregator pom to be specific with all the projects in the modules section in dependency order. Jenkins runs our magic groovy/bash foo that will pull all the projects update the versions to the latest and then checkin the poms (again done in dependency order based on the modules section).
For each project if the pom has changed (because of a version change in some dependency) it is checked in and then we immediately ping jenkins to run the corresponding job for that project (this is to preserve build dependency order otherwise you are at the mercy of the SCM Poll scheduler).
At this point I'm of the opinion it is a good thing to have the release and auto version a separate tool from your general build anyway.
Now you might think maven sort of sucks because of the problems listed above but this actually would be fairly difficult with a build tool that does not have a declarative easy to parse extendable syntax (aka XML).
In fact we add custom XML attributes through namespaces to help hint bash/groovy scripts (e.g. don't update this version).
The dependencies syntax is located at the Dependency Version Requirement Specification documentation. Here it is is for completeness:
Dependencies' version element define version requirements, used to compute effective dependency version. Version requirements have the following syntax:
1.0: "Soft" requirement on 1.0 (just a recommendation, if it matches all other ranges for the dependency)
[1.0]: "Hard" requirement on 1.0
(,1.0]: x <= 1.0
[1.2,1.3]: 1.2 <= x <= 1.3
[1.0,2.0): 1.0 <= x < 2.0
[1.5,): x >= 1.5
(,1.0],[1.2,): x <= 1.0 or x >= 1.2; multiple sets are comma-separated
(,1.1),(1.1,): this excludes 1.1 (for example if it is known not to
work in combination with this library)
In your case, you could do something like <version>[1.2.3,)</version>
Are you possibly depending on development versions that obviously change a lot during development?
Instead of incrementing the version of development releases, you could just use a snapshot version that you overwrite when necessary, which means you wouldn't have to change the version tag on every minor change. Something like 1.0-SNAPSHOT...
But maybe you are trying to achieve something else ;)
Who ever is using LATEST, please make sure you have -U otherwise the latest snapshot won't be pulled.
mvn -U dependency:copy -Dartifact=com.foo:my-foo:LATEST
// pull the latest snapshot for my-foo from all repositories
The truth is even in 3.x it still works, surprisingly the projects builds and deploys. But the LATEST/RELEASE keyword causing problems in m2e and eclipse all over the place, ALSO projects depends on the dependency which deployed through the LATEST/RELEASE fail to recognize the version.
It will also causing problem if you are try to define the version as property, and reference it else where.
So the conclusion is use the versions-maven-plugin if you can.
By the time this question was posed there were some kinks with version ranges in maven, but these have been resolved in newer versions of maven.
This article captures very well how version ranges work and best practices to better understand how maven understands versions: https://docs.oracle.com/middleware/1212/core/MAVEN/maven_version.htm#MAVEN8855
Sometimes you don't want to use version ranges, because it seems that they are "slow" to resolve your dependencies, especially when there is continuous delivery in place and there are tons of versions - mainly during heavy development.
One workaround would be to use the versions-maven-plugin. For example, you can declare a property:
<properties>
<myname.version>1.1.1</myname.version>
</properties>
and add the versions-maven-plugin to your pom file:
<build>
<plugins>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>versions-maven-plugin</artifactId>
<version>2.3</version>
<configuration>
<properties>
<property>
<name>myname.version</name>
<dependencies>
<dependency>
<groupId>group-id</groupId>
<artifactId>artifact-id</artifactId>
<version>latest</version>
</dependency>
</dependencies>
</property>
</properties>
</configuration>
</plugin>
</plugins>
</build>
Then, in order to update the dependency, you have to execute the goals:
mvn versions:update-properties validate
If there is a version newer than 1.1.1, it will tell you:
[INFO] Updated ${myname.version} from 1.1.1 to 1.3.2
If you want Maven should use the latest version of a dependency, then you can use Versions Maven Plugin and how to use this plugin, Tim has already given a good answer, follow his answer.
But as a developer, I will not recommend this type of practices. WHY?
answer to why is already given by Pascal Thivent in the comment of the question
I really don't recommend this practice (nor using version ranges) for
the sake of build reproducibility. A build that starts to suddenly
fail for an unknown reason is way more annoying than updating manually
a version number.
I will recommend this type of practice:
<properties>
<spring.version>3.1.2.RELEASE</spring.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>${spring.version}</version>
</dependency>
</dependencies>
it is easy to maintain and easy to debug. You can update your POM in no time.
MY solution in maven 3.5.4 ,use nexus, in eclipse:
<dependency>
<groupId>yilin.sheng</groupId>
<artifactId>webspherecore</artifactId>
<version>LATEST</version>
</dependency>
then in eclipse: atl + F5, and choose the force update of snapshots/release
it works for me.
I have a project which I am attempting to install with maven. The pom.xml has a few properties in it which are modified when the maven install command is run depending on whatever version of a library we are attempting to build with:
<properties>
<some-version>0</some-version>
</properties>
The zero here is a placeholder, as we'll always specify a legitimate version during our build process. The version is then referenced later in the pom.xml to specify a few dependencies:
<dependencies>
<dependency>
<groupId>com.mycompany.myproduct</groupId>
<artifactId>someOtherProject</artifactId>
<version>${some-version}</version>
</dependency>
</dependencies
Building is done via make with the following commandline:
mvn -Dsome-version=1.6.2
Maven is able to correctly resolve the version and build as expected. However, the version being installed in my local maven repository (/home/user/.m2) doesn't have the correct version. The pom.xml that is installed does not have the updated version I set in the command line:
user#ubuntu:~/$ cat /home/user/.m2/repository/com/mycompany/myproduct/myproject/1.0.0/myproject-1.0.0.pom | grep some-version -C 1
<properties>
<some-version>0</some-version>
</properties>
--
<artifactId>someOtherProject</artifactId>
<version>${some-version}</version>
</dependency>
user#ubuntu:~/$
This is preventing any other project which depends on myproject from being able to build, as maven will complain that it can't find version 0 of someOtherProject:
[ERROR] Failed to execute goal on project myproject:
Could not resolve dependencies for project mycompany.myproduct:myproject:jar:1.0.0:
The following artifacts could not be resolved: com.mycompany.myproduct:someOtherProject:jar:0,
Could not find artifact com.mycompany.myproduct:someOtherProject:jar:0 in central (https://mycompany.com/artifactory/repo/) -> [Help 1]
What do I need to do for maven to install with the updated version in the pom? Obviously a terrible hackish solution would be to use sed and modify the pom file directly, but it seems that Maven should be able to actually leverage the command line settings when installing the pom. Otherwise the ability to set arguments on the command line seems remarkably limited in effectiveness.
Better you may set your property in pom.xml in <properties> tag like this -
<properties>
<property>
<name>some-version</name>
<value>1.6.2</value>
</property>
</properties>
If you use this then you don't have to provide the property each time you issue a mvn command from terminal.
mvn -Dsome-version=1.6.2 works as a substitution value for the scope of building than replacing the original POM with the new values. Hence is the behavior you see. I am not aware of any maven support to do so.
Under #JoopEggen's advice, I looked deeper into the maven versions plugin. It offered an update-property target which will actually update the pom.xml value on disk, rather than just passing in an overwrite during the build phase. I was able to solve my issue by calling
mvn versions:update-property -Dproperty=some-version -DnewVersion=1.6.2 -DsearchReactor=false -DallowSnapshots=true
in the makefile before calling mvn install. Disabling the reactor was necessary to prevent the plugin from rejecting values it couldn't find in the remote repo (see here), and allowSnapshots allows me to use version numbers such as 1.6.2-SNAPSHOT, useful when testing.
My Maven project has a dependency on a non-Maven library, which is coded as a system dependency:
<dependency>
<groupId>com.example</groupId>
<artifactId>foo</artifactId>
<version>${foo.version}</version>
<scope>system</scope>
<systemPath>${foo.jar}</systemPath>
</dependency>
where the location of the library can be controlled via local properties:
<properties>
<foo.version>2.1.1</foo.version>
<foo.basedir>/usr/local</foo.basedir>
<foo.libdir>${foo.basedir}/lib</foo.libdir>
<foo.jar>${foo.basedir}/java/foo-${foo.version}.jar</foo.jar>
</properties>
Recently, the library switched from version 2.1.1 to version 2.2.0, so I changed the foo.version property, but Maven seems to be stuck on the old version:
...
[ERROR] BUILD ERROR
[INFO] ------------------------------------------------------------------------
[INFO] Failed to resolve artifact.
Missing:
----------
1) com.example:foo:jar:2.1.1
...
I have run mvn dependency:purge-local-repository (many times, actually). The string 2.1.1 does not appear anywhere in my POM, profiles.xml, or settings.xml. Still, every time I try to build my project, Maven fails with the above error.
What's going on here? Where is Maven storing the dependency version information and how can I update it?
I think the ${foo.version} might be getting resolved as a filter property. Can you check the properties file under src/main/filters.
Not sure if this is indeed the problem but just give it a try and update back.
The other reason that I could think of is - there might be a transitive dependency on com.example:foo:jar:2.1.1. That is some other dependency which needs 2.1.1 version of this artifact. You can find which artifact is bringing this transitively by doing mvn dependency:tree
You know what. Seeing the workaround that #Chris Conway found, I think that this might have been "solved" by simply running mvn clean.
And even if it would not have helped here, it is always worth trying mvn clean when something strange happens.
Dependency version conflict is a very common problem and most of the time when we start building our application, we never focus or generally we forgot on that aspect until and unless our application starts behaving in an unexpected way or getting started some exception.
For readers and visitors of SO who are interested in knowing the reason why dependency conflicts arises and how we can avoid them in our application , I found a source here explained in a precise way ,so i thought of adding my 2 bits to it .
http://techidiocy.com/maven-dependency-version-conflict-problem-and-resolution/
Cheers