001////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code for adherence to a set of rules.
003// Copyright (C) 2001-2017 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.api.AbstractCheck;
023import com.puppycrawl.tools.checkstyle.api.DetailAST;
024import com.puppycrawl.tools.checkstyle.api.TokenTypes;
025
026/**
027 * <p>
028 * Detects empty statements (standalone ';').
029 * Empty statements often introduce bugs
030 * that are hard to spot, such as in
031 * </p>
032 * <pre>
033 * if (someCondition);
034 *   doConditionalStuff();
035 * doUnconditionalStuff();
036 * </pre>
037 * <p>
038 * An example of how to configure the check is:
039 * </p>
040 * <pre>
041 * &lt;module name="EmptyStatement"/&gt;
042 * </pre>
043 * @author Rick Giles
044 */
045public class EmptyStatementCheck extends AbstractCheck {
046
047    /**
048     * A key is pointing to the warning message text in "messages.properties"
049     * file.
050     */
051    public static final String MSG_KEY = "empty.statement";
052
053    @Override
054    public int[] getDefaultTokens() {
055        return getAcceptableTokens();
056    }
057
058    @Override
059    public int[] getAcceptableTokens() {
060        return new int[] {TokenTypes.EMPTY_STAT};
061    }
062
063    @Override
064    public int[] getRequiredTokens() {
065        return getAcceptableTokens();
066    }
067
068    @Override
069    public void visitToken(DetailAST ast) {
070        log(ast.getLineNo(), ast.getColumnNo(), MSG_KEY);
071    }
072}