001///////////////////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
003// Copyright (C) 2001-2026 the original author or authors.
004//
005// This library is free software; you can redistribute it and/or
006// modify it under the terms of the GNU Lesser General Public
007// License as published by the Free Software Foundation; either
008// version 2.1 of the License, or (at your option) any later version.
009//
010// This library is distributed in the hope that it will be useful,
011// but WITHOUT ANY WARRANTY; without even the implied warranty of
012// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
013// Lesser General Public License for more details.
014//
015// You should have received a copy of the GNU Lesser General Public
016// License along with this library; if not, write to the Free Software
017// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
018///////////////////////////////////////////////////////////////////////////////////////////////
019
020package com.puppycrawl.tools.checkstyle.checks.coding;
021
022import com.puppycrawl.tools.checkstyle.StatelessCheck;
023import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
024import com.puppycrawl.tools.checkstyle.api.DetailAST;
025import com.puppycrawl.tools.checkstyle.api.TokenTypes;
026import com.puppycrawl.tools.checkstyle.utils.TokenUtil;
027
028/**
029 * <div>
030 *  Checks that enum definition does not contain a trailing comma.
031 *  Rationale: JLS allows trailing commas in arrays and enumerations, but does not allow
032 *  them in other locations. To unify the coding style, the use of trailing commas should
033 *  be prohibited.
034 * </div>
035 * <div class="wrapper"><pre class="prettyprint"><code class="language-java">
036 * enum Foo1 {
037 *   FOO,
038 *   BAR;
039 * }
040 * </code></pre></div>
041 *
042 * <p>
043 *  The check demands that there should not be any comma after last constant in
044 *  enum definition.
045 * </p>
046 * <div class="wrapper"><pre class="prettyprint"><code class="language-java">
047 * enum Foo1 {
048 *   FOO,
049 *   BAR, // violation
050 * }
051 * </code></pre></div>
052 *
053 * @since 8.29
054 */
055@StatelessCheck
056public class NoEnumTrailingCommaCheck extends AbstractCheck {
057
058    /**
059     * A key is pointing to the warning message text in "messages.properties"
060     * file.
061     */
062    public static final String MSG_KEY = "no.enum.trailing.comma";
063
064    /**
065     * Creates a new {@code NoEnumTrailingCommaCheck} instance.
066     */
067    public NoEnumTrailingCommaCheck() {
068        // no code by default
069    }
070
071    @Override
072    public int[] getDefaultTokens() {
073        return getRequiredTokens();
074    }
075
076    @Override
077    public int[] getAcceptableTokens() {
078        return getRequiredTokens();
079    }
080
081    @Override
082    public int[] getRequiredTokens() {
083        return new int[] {TokenTypes.ENUM_DEF};
084    }
085
086    @Override
087    public void visitToken(DetailAST detailAST) {
088        final DetailAST enumBlock = detailAST.findFirstToken(TokenTypes.OBJBLOCK);
089        TokenUtil.findFirstTokenByPredicate(enumBlock,
090            node -> TokenUtil.isOfType(node, TokenTypes.SEMI, TokenTypes.RCURLY))
091            .map(DetailAST::getPreviousSibling)
092            .filter(token -> token.getType() == TokenTypes.COMMA)
093            .ifPresent(comma -> log(comma, MSG_KEY));
094    }
095
096}