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.sizes;
21
22 import java.io.File;
23 import java.util.regex.Pattern;
24
25 import com.puppycrawl.tools.checkstyle.StatelessCheck;
26 import com.puppycrawl.tools.checkstyle.api.AbstractFileSetCheck;
27 import com.puppycrawl.tools.checkstyle.api.FileText;
28 import com.puppycrawl.tools.checkstyle.utils.CommonUtil;
29
30 /**
31 * <div>
32 * Checks for long lines.
33 * </div>
34 *
35 * <p>
36 * Rationale: Long lines are hard to read in printouts or if developers
37 * have limited screen space for the source code, e.g. if the IDE displays
38 * additional information like project tree, class hierarchy, etc.
39 * </p>
40 * <ul>
41 * <li>
42 * Notes:
43 * The calculation of the length of a line takes into account the number of
44 * expanded spaces for a tab character ({@code '\t'}). The default number of spaces is {@code 8}.
45 * To specify a different number of spaces, the user can set
46 * <a href="https://checkstyle.org/config.html#Checker">{@code Checker}</a>
47 * property {@code tabWidth} which applies to all Checks, including {@code LineLength};
48 * or can set property {@code tabWidth} for {@code LineLength} alone.
49 * </li>
50 * <li>
51 * By default, package and import statements (lines matching pattern {@code ^(package|import) .*})
52 * are not verified by this check.
53 * </li>
54 * <li>
55 * Trailing comments are taken into consideration while calculating the line length.
56 * <div class="wrapper"><pre class="prettyprint"><code class="language-java">
57 * import java.util.regex.Pattern; // The length of this comment will be taken into consideration
58 * </code></pre></div>
59 * In the example above the length of the import statement is just 31 characters but total length
60 * will be 94 characters.
61 * </li>
62 * </ul>
63 * <ul>
64 * <li>
65 * Property {@code fileExtensions} - Specify the file extensions of the files to process.
66 * Type is {@code java.lang.String[]}.
67 * Default value is {@code ""}.
68 * Since version 8.24
69 * </li>
70 * <li>
71 * Property {@code ignorePattern} - Specify pattern for lines to ignore.
72 * Type is {@code java.util.regex.Pattern}.
73 * Default value is {@code "^(package|import) .*"}.
74 * </li>
75 * <li>
76 * Property {@code max} - Specify the maximum line length allowed.
77 * Type is {@code int}.
78 * Default value is {@code 80}.
79 * </li>
80 * </ul>
81 *
82 * <p>
83 * Parent is {@code com.puppycrawl.tools.checkstyle.Checker}
84 * </p>
85 *
86 * <p>
87 * Violation Message Keys:
88 * </p>
89 * <ul>
90 * <li>
91 * {@code maxLineLen}
92 * </li>
93 * </ul>
94 *
95 * @since 3.0
96 */
97 @StatelessCheck
98 public class LineLengthCheck extends AbstractFileSetCheck {
99
100 /**
101 * A key is pointing to the warning message text in "messages.properties"
102 * file.
103 */
104 public static final String MSG_KEY = "maxLineLen";
105
106 /** Default maximum number of columns in a line. */
107 private static final int DEFAULT_MAX_COLUMNS = 80;
108
109 /** Specify the maximum line length allowed. */
110 private int max = DEFAULT_MAX_COLUMNS;
111
112 /** Specify pattern for lines to ignore. */
113 private Pattern ignorePattern = Pattern.compile("^(package|import) .*");
114
115 @Override
116 protected void processFiltered(File file, FileText fileText) {
117 for (int i = 0; i < fileText.size(); i++) {
118 final String line = fileText.get(i);
119 final int realLength = CommonUtil.lengthExpandedTabs(
120 line, line.codePointCount(0, line.length()), getTabWidth());
121
122 if (realLength > max && !ignorePattern.matcher(line).find()) {
123 log(i + 1, MSG_KEY, max, realLength);
124 }
125 }
126 }
127
128 /**
129 * Setter to specify the maximum line length allowed.
130 *
131 * @param length the maximum length of a line
132 * @since 3.0
133 */
134 public void setMax(int length) {
135 max = length;
136 }
137
138 /**
139 * Setter to specify pattern for lines to ignore.
140 *
141 * @param pattern a pattern.
142 * @since 3.0
143 */
144 public final void setIgnorePattern(Pattern pattern) {
145 ignorePattern = pattern;
146 }
147
148 }