Built by Maven

Require Java Version

This rule enforces certain Java JDK versions. The rule uses the Enforcer version range syntax to define allowed versions.

The following parameters are supported by this rule:

  • message - an optional message to the user if the rule fails.
  • version - range of allowed JDKs.
  • display - flag to display the normalized JDK version.

    For JDK 1.8 you can also use simple 8 as version - it will be internally changed to 1.8

The JDK version is retrieved and the following processing occurs before being checked:

  1. Drop all non-numeric characters preceding the first number. (build 1.5.0_07-b03 becomes 1.5.0_07-b03)
  2. Replace all '_' and '-' with '.' (1.5.0_07-b03 becomes 1.5.0.07.b03)
  3. Remove all non digit characters "[^0-9] and convert each section using Integer.parseInt() (1.5.0_07-b03 becomes 1.5.0.7.3)
  4. Split the string on '.' and take the first 3 sections, separated by '.' and add '-' followed by the fourth section (1.5.0.7.3 becomes 1.5.0-7)

This preprocessing normalizes various JDK version strings into a standard x.y.z-b version number. Your required range should therefore use the x.y.z-b format for comparison. There is an easy way to see how your current JDK string will be normalized, you can enable display option.

Sample Plugin Configuration:

<project>
  [...]
  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-enforcer-plugin</artifactId>
        <version>3.4.1</version>
        <executions>
          <execution>
            <id>enforce-java</id>
            <goals>
              <goal>enforce</goal>
            </goals>
            <configuration>
              <rules>
                <requireJavaVersion>
                  <version>1.6.0</version>
                </requireJavaVersion>
              </rules>    
            </configuration>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
  [...]
</project>

If you would like to enforce a certain vendor string for the JDK, you would use the RequireJavaVendor rule