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;
026
027/**
028 * <div>
029 * Checks that array initialization do not contain a trailing comma.
030 * Rationale: JLS allows trailing commas in arrays and enumerations, but does not allow
031 * them in other locations. To unify the coding style, the use of trailing commas should
032 * be prohibited.
033 * </div>
034 * {@snippet lang="text" :
035 * int[] foo = new int[] {
036 *   1,
037 *   2
038 * };
039 * }
040 *
041 * <p>
042 * The check demands that there should not be any comma after the last element of an array.
043 * </p>
044 * {@snippet lang="text" :
045 * String[] foo = new String[] {
046 *   "FOO",
047 *   "BAR", // violation
048 * }
049 * }
050 *
051 * @since 8.28
052 */
053@StatelessCheck
054public class NoArrayTrailingCommaCheck extends AbstractCheck {
055
056    /**
057     * A key is pointing to the warning message text in "messages.properties" file.
058     */
059    public static final String MSG_KEY = "no.array.trailing.comma";
060
061    /**
062     * Creates a new {@code NoArrayTrailingCommaCheck} instance.
063     */
064    public NoArrayTrailingCommaCheck() {
065        // no code by default
066    }
067
068    @Override
069    public int[] getDefaultTokens() {
070        return getRequiredTokens();
071    }
072
073    @Override
074    public int[] getAcceptableTokens() {
075        return getRequiredTokens();
076    }
077
078    @Override
079    public int[] getRequiredTokens() {
080        return new int[] {TokenTypes.ARRAY_INIT};
081    }
082
083    @Override
084    public void visitToken(DetailAST arrayInit) {
085        final DetailAST rcurly = arrayInit.findFirstToken(TokenTypes.RCURLY);
086        final DetailAST previousSibling = rcurly.getPreviousSibling();
087        if (previousSibling != null && previousSibling.getType() == TokenTypes.COMMA) {
088            log(previousSibling, MSG_KEY);
089        }
090    }
091
092}