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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:

  1. <project>
  2.   [...]
  3.   <build>
  4.     <plugins>
  5.       <plugin>
  6.         <groupId>org.apache.maven.plugins</groupId>
  7.         <artifactId>maven-enforcer-plugin</artifactId>
  8.         <version>3.5.0</version>
  9.         <executions>
  10.           <execution>
  11.             <id>enforce-java</id>
  12.             <goals>
  13.               <goal>enforce</goal>
  14.             </goals>
  15.             <configuration>
  16.               <rules>
  17.                 <requireJavaVersion>
  18.                   <version>1.6.0</version>
  19.                 </requireJavaVersion>
  20.               </rules>    
  21.             </configuration>
  22.           </execution>
  23.         </executions>
  24.       </plugin>
  25.     </plugins>
  26.   </build>
  27.   [...]
  28. </project>

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