Building a Java project

What This Guide Covers

This guide covers build environment and configuration topics specific to Java projects. Please make sure to read our Getting Started and general build configuration guides first.

Overview

The Travis CI environment provides recent versions of Oracle JDK 8 (default), Oracle JDK 9, OpenJDK 7, Gradle 2.0, Maven 3.2 and Ant 1.8, and has sensible defaults for projects that use Gradle, Maven or Ant.

To use the Java environment add the following to your .travis.yml:

language: java

Older OpenJDK and Oracle JDK versions may be available on Precise.

Projects Using Maven

Default script Command

If your project has pom.xml file in the repository root but no build.gradle, Travis CI builds your project with Maven 3:

mvn test -B

If your project also includes the mvnw wrapper script in the repository root, Travis CI uses that instead:

./mvnw test -B

The default command does not generate JavaDoc (-Dmaven.javadoc.skip=true).

To use a different build command, customize the build step.

Dependency Management

Before running the build, Travis CI installs dependencies:

mvn install -DskipTests=true -Dmaven.javadoc.skip=true -B -V

or if your project uses the mvnw wrapper script:

./mvnw install -DskipTests=true -Dmaven.javadoc.skip=true -B -V

Projects Using Gradle

Default script Command

If your project has build.gradle file in the repository root, Travis CI builds your project with Gradle:

gradle check

If your project also includes the gradlew wrapper script in the repository root, Travis CI uses that instead:

./gradlew check

To use a different build command, customize the build step.

Dependency Management

Before running the build, Travis CI installs dependencies:

gradle assemble

or

./gradlew assemble

Caching

A peculiarity of dependency caching in Gradle means that to avoid uploading the cache after every build you need to add the following lines to your .travis.yml:

before_cache:
  - rm -f  $HOME/.gradle/caches/modules-2/modules-2.lock
  - rm -fr $HOME/.gradle/caches/*/plugin-resolution/
cache:
  directories:
    - $HOME/.gradle/caches/
    - $HOME/.gradle/wrapper/

Gradle daemon is disabled by default

As recommended by the Gradle team, the Gradle daemon is disabled by default. If you would like to run gradle with daemon, add --daemon to the invocation.

Projects Using Ant

Default script Command

If Travis CI does not detect Maven or Gradle files it runs Ant:

ant test

Dependency Management

Because there is no single standard way of installing project dependencies with Ant, you need to specify the exact command to run using install: key in your .travis.yml, for example:

language: java
install: ant deps

Testing Against Multiple JDKs

To test against multiple JDKs, use the jdk: key in .travis.yml. For example, to test against Oracle JDKs 8 and 9, as well as OpenJDK 7:

jdk:
  - oraclejdk8
  - oraclejdk9
  - openjdk7

Note that testing against multiple Java versions is not supported on OS X. See the OS X Build Environment for more details.

Travis CI provides OpenJDK 7, Oracle JDK 8, and Oracle JDK 9.

Updating Oracle JDK to a recent release

Your repository may require a newer release of Oracle JDK than the pre-installed version. (You can consult the list of published Oracle JDK packages.)

The following example will use the latest Oracle JDK 8:

sudo: false
addons:
  apt:
    packages:
      - oracle-java8-installer

Build Matrix

For Java projects, env and jdk can be given as arrays to construct a build matrix.

Switching JDKs Within One Job

If your build needs to switch JDKs during a job, you can do so with jdk_switcher use ….

script:
  - jdk_switcher use oraclejdk8
  - # do stuff with Java 8
  - jdk_switcher use openjdk7
  - # do stuff with Java 7

Use of jdk_switcher also updates $JAVA_HOME appropriately.

Examples