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.whitespace;
21
22 import java.io.File;
23
24 import com.puppycrawl.tools.checkstyle.StatelessCheck;
25 import com.puppycrawl.tools.checkstyle.api.AbstractFileSetCheck;
26 import com.puppycrawl.tools.checkstyle.api.FileText;
27
28 /**
29 * <div>
30 * Checks that there are no tab characters ({@code '\t'}) in the source code.
31 * </div>
32 *
33 * <p>
34 * Rationale:
35 * </p>
36 * <ul>
37 * <li>
38 * Developers should not need to configure the tab width of their text editors in order
39 * to be able to read source code.
40 * </li>
41 * <li>
42 * From the Apache jakarta coding standards: In a distributed development environment,
43 * when the commit messages get sent to a mailing list, they are almost impossible to
44 * read if you use tabs.
45 * </li>
46 * </ul>
47 *
48 * <p>
49 * When the {@code FileTabCharacter} check is used with the default configuration,
50 * only the first instance of a tab character is reported.
51 * </p>
52 *
53 * <ul>
54 * <li>
55 * Property {@code eachLine} - Control whether to report on each line containing a tab,
56 * or just the first instance.
57 * Type is {@code boolean}.
58 * Default value is {@code false}.
59 * </li>
60 * <li>
61 * Property {@code fileExtensions} - Specify the file extensions of the files to process.
62 * Type is {@code java.lang.String[]}.
63 * Default value is {@code ""}.
64 * </li>
65 * </ul>
66 *
67 * <p>
68 * Parent is {@code com.puppycrawl.tools.checkstyle.Checker}
69 * </p>
70 *
71 * <p>
72 * Violation Message Keys:
73 * </p>
74 * <ul>
75 * <li>
76 * {@code containsTab}
77 * </li>
78 * <li>
79 * {@code file.containsTab}
80 * </li>
81 * </ul>
82 *
83 * @since 5.0
84 */
85 @StatelessCheck
86 public class FileTabCharacterCheck extends AbstractFileSetCheck {
87
88 /**
89 * A key is pointing to the warning message text in "messages.properties"
90 * file.
91 */
92 public static final String MSG_CONTAINS_TAB = "containsTab";
93
94 /**
95 * A key is pointing to the warning message text in "messages.properties"
96 * file.
97 */
98 public static final String MSG_FILE_CONTAINS_TAB = "file.containsTab";
99
100 /** Control whether to report on each line containing a tab, or just the first instance. */
101 private boolean eachLine;
102
103 @Override
104 protected void processFiltered(File file, FileText fileText) {
105 int lineNum = 0;
106 for (int index = 0; index < fileText.size(); index++) {
107 final String line = fileText.get(index);
108 lineNum++;
109 final int tabPosition = line.indexOf('\t');
110 if (tabPosition != -1) {
111 if (eachLine) {
112 log(lineNum, tabPosition, MSG_CONTAINS_TAB);
113 }
114 else {
115 log(lineNum, tabPosition, MSG_FILE_CONTAINS_TAB);
116 break;
117 }
118 }
119 }
120 }
121
122 /**
123 * Setter to control whether to report on each line containing a tab, or just the first
124 * instance.
125 *
126 * @param eachLine Whether report on each line containing a tab.
127 * @since 5.0
128 */
129 public void setEachLine(boolean eachLine) {
130 this.eachLine = eachLine;
131 }
132
133 }