code: ///////////////////////////////////////////////////////////////////////////////////////////////
  // checkstyle: Checks Java source code and other text files for adherence to a set of rules.
  // Copyright (C) 2001-2023 the original author or authors.
  //
  // This library is free software; you can redistribute it and/or
  // modify it under the terms of the GNU Lesser General Public
  // License as published by the Free Software Foundation; either
  // version 2.1 of the License, or (at your option) any later version.
  //
  // This library is distributed in the hope that it will be useful,
  // but WITHOUT ANY WARRANTY; without even the implied warranty of
  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  // Lesser General Public License for more details.
  //
  // You should have received a copy of the GNU Lesser General Public
  // License along with this library; if not, write to the Free Software
  // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  ///////////////////////////////////////////////////////////////////////////////////////////////
  
  package com.puppycrawl.tools.checkstyle.checks.coding;
  
  import com.puppycrawl.tools.checkstyle.StatelessCheck;
  import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
  import com.puppycrawl.tools.checkstyle.api.DetailAST;
  import com.puppycrawl.tools.checkstyle.api.TokenTypes;
  
  /**
   * <p>
   * Checks if unnecessary semicolon is in enum definitions.
   * Semicolon is not needed if enum body contains only enum constants.
   * </p>
   * <p>
   * To configure the check:
   * </p>
   * <pre>
   * &lt;module name=&quot;UnnecessarySemicolonInEnumeration&quot;/&gt;
   * </pre>
   * <p>
   * Example of violations
   * </p>
   * <pre>
   * enum One {
   *     A,B; // violation
   * }
   * enum Two {
   *     A,B,; // violation
   * }
   * enum Three {
   *     A,B(); // violation
   * }
   * enum Four {
   *     A,B{}; // violation
   * }
   * enum Five {
   *     A,
   *     B
   *     ; // violation
   * }
   * </pre>
   * <p>
   * Example of good cases
   * </p>
   * <pre>
   * enum Normal {
   *     A,
   *     B,
   *     ; // required ";", no violation
   *     Normal(){}
   * }
   * enum NoSemicolon {
   *     A, B // only enum constants, no semicolon required
   * }
   * </pre>
   * <p>
   * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
   * </p>
   * <p>
   * Violation Message Keys:
   * </p>
   * <ul>
   * <li>
   * {@code unnecessary.semicolon}
   * </li>
   * </ul>
   *
   * @since 8.22
   */
  @StatelessCheck
  public final class UnnecessarySemicolonInEnumerationCheck extends AbstractCheck {
  
      /**
       * A key is pointing to the warning message text in "messages.properties"
       * file.
       */
      public static final String MSG_SEMI = "unnecessary.semicolon";
  
      @Override
      public int[] getDefaultTokens() {
          return getRequiredTokens();
      }
  
      @Override
      public int[] getAcceptableTokens() {
          return getRequiredTokens();
      }
  
      @Override
      public int[] getRequiredTokens() {
          return new int[] {
              TokenTypes.ENUM_DEF,
          };
      }
  
      @Override
      public void visitToken(DetailAST ast) {
          final DetailAST enumBlock = ast.findFirstToken(TokenTypes.OBJBLOCK);
          final DetailAST semicolon = enumBlock.findFirstToken(TokenTypes.SEMI);
          if (semicolon != null && isEndOfEnumerationAfter(semicolon)) {
              log(semicolon, MSG_SEMI);
          }
      }
  
      /**
       * Checks if enum body has no code elements after enum constants semicolon.
       *
       * @param ast semicolon in enum constants definition end
       * @return true if there is no code elements, false otherwise.
       */
      private static boolean isEndOfEnumerationAfter(DetailAST ast) {
          return ast.getNextSibling().getType() == TokenTypes.RCURLY;
      }
  }
  