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