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.sizes;
  
  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 for long anonymous inner classes.
   * </p>
   * <p>
   * Rationale: If an anonymous inner class becomes very long
   * it is hard to understand and to see the flow of the method
   * where the class is defined. Therefore, long anonymous inner
   * classes should usually be refactored into a named inner class.
   * See also Bloch, Effective Java, p. 93.
   * </p>
   * <ul>
   * <li>
   * Property {@code max} - Specify the maximum number of lines allowed.
   * Type is {@code int}.
   * Default value is {@code 20}.
   * </li>
   * </ul>
   * <p>
   * To configure the check to accept anonymous classes with up to 20 lines:
   * </p>
   * <pre>
   * &lt;module name="AnonInnerLength"/&gt;
   * </pre>
   * <p>
   * To configure the check to accept anonymous classes with up to 60 lines:
   * </p>
   * <pre>
   * &lt;module name="AnonInnerLength"&gt;
   *   &lt;property name="max" value="60"/&gt;
   * &lt;/module&gt;
   * </pre>
   * <p>
   * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
   * </p>
   * <p>
   * Violation Message Keys:
   * </p>
   * <ul>
   * <li>
   * {@code maxLen.anonInner}
   * </li>
   * </ul>
   *
   * @since 3.2
   */
  @StatelessCheck
  public class AnonInnerLengthCheck extends AbstractCheck {
  
      /**
       * A key is pointing to the warning message text in "messages.properties"
       * file.
       */
      public static final String MSG_KEY = "maxLen.anonInner";
  
      /** Default maximum number of lines. */
      private static final int DEFAULT_MAX = 20;
  
      /** Specify the maximum number of lines allowed. */
      private int max = DEFAULT_MAX;
  
      @Override
      public int[] getDefaultTokens() {
          return getRequiredTokens();
      }
  
      @Override
      public int[] getAcceptableTokens() {
          return getRequiredTokens();
      }
  
      @Override
      public int[] getRequiredTokens() {
          return new int[] {TokenTypes.LITERAL_NEW};
      }
  
      @Override
      public void visitToken(DetailAST ast) {
          final DetailAST openingBrace = ast.findFirstToken(TokenTypes.OBJBLOCK);
          if (openingBrace != null) {
              final DetailAST closingBrace =
                  openingBrace.findFirstToken(TokenTypes.RCURLY);
              final int length =
                  closingBrace.getLineNo() - openingBrace.getLineNo() + 1;
              if (length > max) {
                  log(ast, MSG_KEY, length, max);
              }
          }
      }
  
      /**
       * Setter to specify the maximum number of lines allowed.
       *
       * @param length the maximum length of an anonymous inner class.
       */
      public void setMax(int length) {
          max = length;
      }
  
  }
  