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 java.util.HashMap;
  import java.util.Map;
  
  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;
  import com.puppycrawl.tools.checkstyle.utils.TokenUtil;
  
  /**
   * <p>
   * Checks that overloaded methods are grouped together. Overloaded methods have the same
   * name but different signatures where the signature can differ by the number of
   * input parameters or type of input parameters or both.
   * </p>
   * <p>
   * To configure the check:
   * </p>
   * <pre>
   * &lt;module name=&quot;OverloadMethodsDeclarationOrder&quot;/&gt;
   * </pre>
   * <p>
   * Example of correct grouping of overloaded methods:
   * </p>
   * <pre>
   * public void foo(int i) {}
   * public void foo(String s) {}
   * public void foo(String s, int i) {}
   * public void foo(int i, String s) {}
   * public void notFoo() {}
   * </pre>
   * <p>
   * Example of incorrect grouping of overloaded methods:
   * </p>
   * <pre>
   * public void foo(int i) {} // OK
   * public void foo(String s) {} // OK
   * public void notFoo() {} // violation. Have to be after foo(String s, int i)
   * public void foo(int i, String s) {}
   * public void foo(String s, int i) {}
   * </pre>
   * <p>
   * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
   * </p>
   * <p>
   * Violation Message Keys:
   * </p>
   * <ul>
   * <li>
   * {@code overload.methods.declaration}
   * </li>
   * </ul>
   *
   * @since 5.8
   */
  @StatelessCheck
  public class OverloadMethodsDeclarationOrderCheck extends AbstractCheck {
  
      /**
       * A key is pointing to the warning message text in "messages.properties"
       * file.
       */
      public static final String MSG_KEY = "overload.methods.declaration";
  
      @Override
      public int[] getDefaultTokens() {
          return getRequiredTokens();
      }
  
      @Override
      public int[] getAcceptableTokens() {
          return getRequiredTokens();
      }
  
      @Override
      public int[] getRequiredTokens() {
          return new int[] {
              TokenTypes.OBJBLOCK,
          };
      }
  
      @Override
      public void visitToken(DetailAST ast) {
          final int parentType = ast.getParent().getType();
  
          final int[] tokenTypes = {
              TokenTypes.CLASS_DEF,
              TokenTypes.ENUM_DEF,
              TokenTypes.INTERFACE_DEF,
              TokenTypes.LITERAL_NEW,
              TokenTypes.RECORD_DEF,
          };
  
          if (TokenUtil.isOfType(parentType, tokenTypes)) {
              checkOverloadMethodsGrouping(ast);
          }
      }
  
      /**
       * Checks that if overload methods are grouped together they should not be
       * separated from each other.
       *
       * @param objectBlock
       *        is a class, interface or enum object block.
       */
      private void checkOverloadMethodsGrouping(DetailAST objectBlock) {
          final int allowedDistance = 1;
          DetailAST currentToken = objectBlock.getFirstChild();
          final Map<String, Integer> methodIndexMap = new HashMap<>();
          final Map<String, Integer> methodLineNumberMap = new HashMap<>();
          int currentIndex = 0;
          while (currentToken != null) {
              if (currentToken.getType() == TokenTypes.METHOD_DEF) {
                  currentIndex++;
                  final String methodName =
                          currentToken.findFirstToken(TokenTypes.IDENT).getText();
                  final Integer previousIndex = methodIndexMap.get(methodName);
                  if (previousIndex != null && currentIndex - previousIndex > allowedDistance) {
                      final int previousLineWithOverloadMethod =
                              methodLineNumberMap.get(methodName);
                      log(currentToken, MSG_KEY,
                              previousLineWithOverloadMethod);
                  }
                  methodIndexMap.put(methodName, currentIndex);
                  methodLineNumberMap.put(methodName, currentToken.getLineNo());
              }
              currentToken = currentToken.getNextSibling();
          }
      }
  
  }
  