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1   ///////////////////////////////////////////////////////////////////////////////////////////////
2   // checkstyle: Checks Java source code and other text files for adherence to a set of rules.
3   // Copyright (C) 2001-2025 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;
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.utils.CommonUtil;
26  
27  /**
28   * <div>
29   * Checks whether file contains code.
30   * Java compiler is not raising errors on files with no code or all commented out.
31   * Files which are considered to have no code:
32   * </div>
33   *
34   * <ul>
35   * <li>
36   * File with no text
37   * </li>
38   * <li>
39   * File with single-line comment(s)
40   * </li>
41   * <li>
42   * File with a multi line comment(s).
43   * </li>
44   * </ul>
45   *
46   * @since 8.33
47   */
48  @StatelessCheck
49  public class NoCodeInFileCheck extends AbstractCheck {
50  
51      /**
52       * A key is pointing to the warning message text in "messages.properties"
53       * file.
54       */
55      public static final String MSG_KEY_NO_CODE = "nocode.in.file";
56  
57      /** Line number used to log violation when no AST nodes are present in file. */
58      private static final int DEFAULT_LINE_NUMBER = 1;
59  
60      @Override
61      public int[] getDefaultTokens() {
62          return getRequiredTokens();
63      }
64  
65      @Override
66      public int[] getAcceptableTokens() {
67          return getRequiredTokens();
68      }
69  
70      @Override
71      public int[] getRequiredTokens() {
72          return CommonUtil.EMPTY_INT_ARRAY;
73      }
74  
75      @Override
76      public void finishTree(DetailAST ast) {
77          if (ast == null) {
78              log(DEFAULT_LINE_NUMBER, MSG_KEY_NO_CODE);
79          }
80      }
81  }