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1   ////////////////////////////////////////////////////////////////////////////////
2   // checkstyle: Checks Java source code for adherence to a set of rules.
3   // Copyright (C) 2001-2017 the original author or authors.
4   //
5   // This library is free software; you can redistribute it and/or
6   // modify it under the terms of the GNU Lesser General Public
7   // License as published by the Free Software Foundation; either
8   // version 2.1 of the License, or (at your option) any later version.
9   //
10  // This library is distributed in the hope that it will be useful,
11  // but WITHOUT ANY WARRANTY; without even the implied warranty of
12  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13  // Lesser General Public License for more details.
14  //
15  // You should have received a copy of the GNU Lesser General Public
16  // License along with this library; if not, write to the Free Software
17  // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
18  ////////////////////////////////////////////////////////////////////////////////
19  
20  package com.puppycrawl.tools.checkstyle.checks.coding;
21  
22  import com.puppycrawl.tools.checkstyle.StatelessCheck;
23  import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
24  import com.puppycrawl.tools.checkstyle.api.DetailAST;
25  import com.puppycrawl.tools.checkstyle.api.TokenTypes;
26  
27  /**
28   * <p>
29   * Detects empty statements (standalone ';').
30   * Empty statements often introduce bugs
31   * that are hard to spot, such as in
32   * </p>
33   * <pre>
34   * if (someCondition);
35   *   doConditionalStuff();
36   * doUnconditionalStuff();
37   * </pre>
38   * <p>
39   * An example of how to configure the check is:
40   * </p>
41   * <pre>
42   * &lt;module name="EmptyStatement"/&gt;
43   * </pre>
44   * @author Rick Giles
45   */
46  @StatelessCheck
47  public class EmptyStatementCheck extends AbstractCheck {
48  
49      /**
50       * A key is pointing to the warning message text in "messages.properties"
51       * file.
52       */
53      public static final String MSG_KEY = "empty.statement";
54  
55      @Override
56      public int[] getDefaultTokens() {
57          return getRequiredTokens();
58      }
59  
60      @Override
61      public int[] getAcceptableTokens() {
62          return getRequiredTokens();
63      }
64  
65      @Override
66      public int[] getRequiredTokens() {
67          return new int[] {TokenTypes.EMPTY_STAT};
68      }
69  
70      @Override
71      public void visitToken(DetailAST ast) {
72          log(ast.getLineNo(), ast.getColumnNo(), MSG_KEY);
73      }
74  }