001///////////////////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
003// Copyright (C) 2001-2025 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 * Detects empty statements (standalone {@code ";"} semicolon).
030 * Empty statements often introduce bugs that are hard to spot
031 * </div>
032 *
033 * <p>
034 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
035 * </p>
036 *
037 * <p>
038 * Violation Message Keys:
039 * </p>
040 * <ul>
041 * <li>
042 * {@code empty.statement}
043 * </li>
044 * </ul>
045 *
046 * @since 3.1
047 */
048@StatelessCheck
049public class EmptyStatementCheck extends AbstractCheck {
050
051    /**
052     * A key is pointing to the warning message text in "messages.properties"
053     * file.
054     */
055    public static final String MSG_KEY = "empty.statement";
056
057    @Override
058    public int[] getDefaultTokens() {
059        return getRequiredTokens();
060    }
061
062    @Override
063    public int[] getAcceptableTokens() {
064        return getRequiredTokens();
065    }
066
067    @Override
068    public int[] getRequiredTokens() {
069        return new int[] {TokenTypes.EMPTY_STAT};
070    }
071
072    @Override
073    public void visitToken(DetailAST ast) {
074        log(ast, MSG_KEY);
075    }
076
077}