com.puppycrawl.tools.checkstyle.checks.coding.EmptyStatementCheck Maven / Gradle / Ivy

////////////////////////////////////////////////////////////////////////////////
// checkstyle: Checks Java source code for adherence to a set of rules.
// Copyright (C) 2001-2021 the original author or authors.
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
////////////////////////////////////////////////////////////////////////////////

package com.puppycrawl.tools.checkstyle.checks.coding;

import com.puppycrawl.tools.checkstyle.StatelessCheck;
import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
import com.puppycrawl.tools.checkstyle.api.DetailAST;
import com.puppycrawl.tools.checkstyle.api.TokenTypes;

/**
 * 
 * Detects empty statements (standalone {@code ";"} semicolon).
 * Empty statements often introduce bugs that are hard to spot
 * 
 * 
 * To configure the check:
 * 
 *  * <module name="EmptyStatement"/>
 * 
 * 
 * Example:
 * 
 *  * public void foo() {
 *   int i = 5;
 *   if (i > 3); // violation, ";" right after if statement
 *     i++;
 *   for (i = 0; i < 5; i++); // violation
 *     i++;
 *   while (i > 10) // OK
 *     i++;
 * }
 * 
 * 
 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
 * 
 * 
 * Violation Message Keys:
 * 
 * 
 * 
 * {@code empty.statement}
 * 
 * 
 *
 * @since 3.1
 */
@StatelessCheck
public class EmptyStatementCheck extends AbstractCheck {

    /**
     * A key is pointing to the warning message text in "messages.properties"
     * file.
     */
    public static final String MSG_KEY = "empty.statement";

    @Override
    public int[] getDefaultTokens() {
        return getRequiredTokens();
    }

    @Override
    public int[] getAcceptableTokens() {
        return getRequiredTokens();
    }

    @Override
    public int[] getRequiredTokens() {
        return new int[] {TokenTypes.EMPTY_STAT};
    }

    @Override
    public void visitToken(DetailAST ast) {
        log(ast, MSG_KEY);
    }

}