Apache Commons Collections

The Apache Commons Collections package contains types that extend and augment the Java Collections Framework.

Documentation

More information can be found on the Apache Commons Collections homepage. The Javadoc can be browsed. Questions related to the usage of Apache Commons Collections should be posted to the user mailing list.

Getting the latest release

You can download source and binaries from our download page.

Alternatively, you can pull it from the central Maven repositories:

<dependency>
  <groupId>org.apache.commons</groupId>
  <artifactId>commons-collections4</artifactId>
  <version>4.5.0-M2</version>
</dependency>

Building

Building requires a Java JDK and Apache Maven. The required Java version is found in the pom.xml as the maven.compiler.source property.

From a command shell, run mvn without arguments to invoke the default Maven goal to run all tests and checks.

Contributing

We accept Pull Requests via GitHub. The developer mailing list is the main channel of communication for contributors. There are some guidelines which will make applying PRs easier for us:

• No tabs! Please use spaces for indentation.
• Respect the existing code style for each file.
• Create minimal diffs - disable on save actions like reformat source code or organize imports. If you feel the source code should be reformatted create a separate PR for this change.
• Provide JUnit tests for your changes and make sure your changes don't break any existing tests by running mvn.
• Before you pushing a PR, run mvn (by itself), this runs the default goal, which contains all build checks.
• To see the code coverage report, regardless of coverage failures, run mvn clean site -Dcommons.jacoco.haltOnFailure=false

If you plan to contribute on a regular basis, please consider filing a contributor license agreement. You can learn more about contributing via GitHub in our contribution guidelines.

License

This code is licensed under the Apache License v2.

See the NOTICE.txt file for required notices and attributions.

Donating

You like Apache Commons Collections? Then donate back to the ASF to support development.

Additional Resources

• Apache Commons Homepage
• Apache Issue Tracker (JIRA)
• Apache Commons Slack Channel
• Apache Commons Twitter Account

Apache Commons Components

Please see the list of components