code: private static int getJavaVersion() {
      String version = System.getProperty("java.version");
      assert version != null;
      if (version.startsWith("1.")) {
        version = version.substring(2);
      }
      // Allow these formats:
      // 1.8.0_72-ea
      // 9-ea
      // 9
      // 9.0.1
      int dotPos = version.indexOf('.');
      int dashPos = version.indexOf('-');
      return Integer.parseInt(
          version.substring(0, dotPos > -1 ? dotPos : dashPos > -1 ? dashPos : 1));
    }
docs: Returns the Java version as an int value.
  
  @return the Java version as an int value (8, 9, etc.)