Java – Add a dependency in Maven

dependenciesjavamacosmaven-2

How do I take a jar file that I have and add it to the dependency system in maven 2? I will be the maintainer of this dependency and my code needs this jar in the class path so that it will compile.

Best Answer

You'll have to do this in two steps:

1. Give your JAR a groupId, artifactId and version and add it to your repository.

If you don't have an internal repository, and you're just trying to add your JAR to your local repository, you can install it as follows, using any arbitrary groupId/artifactIds:

mvn install:install-file -DgroupId=com.stackoverflow... -DartifactId=yourartifactid... -Dversion=1.0 -Dpackaging=jar -Dfile=/path/to/jarfile

You can also deploy it to your internal repository if you have one, and want to make this available to other developers in your organization. I just use my repository's web based interface to add artifacts, but you should be able to accomplish the same thing using mvn deploy:deploy-file ....

2. Update dependent projects to reference this JAR.

Then update the dependency in the pom.xml of the projects that use the JAR by adding the following to the element:

<dependencies>
    ...
    <dependency>
        <groupId>com.stackoverflow...</groupId>
        <artifactId>artifactId...</artifactId>
        <version>1.0</version>
    </dependency>
    ...
</dependencies>

Related Solutions

Java – How to tell Maven to use the latest version of a dependency

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.

Java – Including all the jars in a directory within the Java classpath

Using Java 6 or later, the classpath option supports wildcards. Note the following:

Use straight quotes (")
Use *, not *.jar

Windows

java -cp "Test.jar;lib/*" my.package.MainClass

Unix

java -cp "Test.jar:lib/*" my.package.MainClass

This is similar to Windows, but uses : instead of ;. If you cannot use wildcards, bash allows the following syntax (where lib is the directory containing all the Java archive files):

java -cp "$(printf %s: lib/*.jar)"

(Note that using a classpath is incompatible with the -jar option. See also: Execute jar file with multiple classpath libraries from command prompt)

Understanding Wildcards

From the Classpath document:

Class path entries can contain the basename wildcard character *, which is considered equivalent to specifying a list of all the files in the directory with the extension .jar or .JAR. For example, the class path entry foo/* specifies all JAR files in the directory named foo. A classpath entry consisting simply of * expands to a list of all the jar files in the current directory.

A class path entry that contains * will not match class files. To match both classes and JAR files in a single directory foo, use either foo;foo/* or foo/*;foo. The order chosen determines whether the classes and resources in foo are loaded before JAR files in foo, or vice versa.

Subdirectories are not searched recursively. For example, foo/* looks for JAR files only in foo, not in foo/bar, foo/baz, etc.

The order in which the JAR files in a directory are enumerated in the expanded class path is not specified and may vary from platform to platform and even from moment to moment on the same machine. A well-constructed application should not depend upon any particular order. If a specific order is required then the JAR files can be enumerated explicitly in the class path.

Expansion of wildcards is done early, prior to the invocation of a program's main method, rather than late, during the class-loading process itself. Each element of the input class path containing a wildcard is replaced by the (possibly empty) sequence of elements generated by enumerating the JAR files in the named directory. For example, if the directory foo contains a.jar, b.jar, and c.jar, then the class path foo/* is expanded into foo/a.jar;foo/b.jar;foo/c.jar, and that string would be the value of the system property java.class.path.

The CLASSPATH environment variable is not treated any differently from the -classpath (or -cp) command-line option. That is, wildcards are honored in all these cases. However, class path wildcards are not honored in the Class-Path jar-manifest header.

Note: due to a known bug in java 8, the windows examples must use a backslash preceding entries with a trailing asterisk: https://bugs.openjdk.java.net/browse/JDK-8131329