001///////////////////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
003// Copyright (C) 2001-2024 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 * <pre>
035 * int[] foo = new int[] {
036 *   1,
037 *   2
038 * };
039 * </pre>
040 *
041 * <p>
042 * The check demands that there should not be any comma after the last element of an array.
043 * </p>
044 * <pre>
045 * String[] foo = new String[] {
046 *   "FOO",
047 *   "BAR", //violation
048 * }
049 * </pre>
050 *
051 * <p>
052 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
053 * </p>
054 *
055 * <p>
056 * Violation Message Keys:
057 * </p>
058 * <ul>
059 * <li>
060 * {@code no.array.trailing.comma}
061 * </li>
062 * </ul>
063 *
064 * @since 8.28
065 */
066@StatelessCheck
067public class NoArrayTrailingCommaCheck extends AbstractCheck {
068
069    /**
070     * A key is pointing to the warning message text in "messages.properties"
071     * file.
072     */
073    public static final String MSG_KEY = "no.array.trailing.comma";
074
075    @Override
076    public int[] getDefaultTokens() {
077        return getRequiredTokens();
078    }
079
080    @Override
081    public int[] getAcceptableTokens() {
082        return getRequiredTokens();
083    }
084
085    @Override
086    public int[] getRequiredTokens() {
087        return new int[] {TokenTypes.ARRAY_INIT};
088    }
089
090    @Override
091    public void visitToken(DetailAST arrayInit) {
092        final DetailAST rcurly = arrayInit.findFirstToken(TokenTypes.RCURLY);
093        final DetailAST previousSibling = rcurly.getPreviousSibling();
094        if (previousSibling != null && previousSibling.getType() == TokenTypes.COMMA) {
095            log(previousSibling, MSG_KEY);
096        }
097    }
098}