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 * 64 * @since 3.0 65 */ 66 @StatelessCheck 67 public class LineLengthCheck extends AbstractFileSetCheck { 68 69 /** 70 * A key is pointing to the warning message text in "messages.properties" 71 * file. 72 */ 73 public static final String MSG_KEY = "maxLineLen"; 74 75 /** Default maximum number of columns in a line. */ 76 private static final int DEFAULT_MAX_COLUMNS = 80; 77 78 /** Specify the maximum line length allowed. */ 79 private int max = DEFAULT_MAX_COLUMNS; 80 81 /** Specify pattern for lines to ignore. */ 82 private Pattern ignorePattern = Pattern.compile("^(package|import) .*"); 83 84 @Override 85 protected void processFiltered(File file, FileText fileText) { 86 for (int i = 0; i < fileText.size(); i++) { 87 final String line = fileText.get(i); 88 final int realLength = CommonUtil.lengthExpandedTabs( 89 line, line.codePointCount(0, line.length()), getTabWidth()); 90 91 if (realLength > max && !ignorePattern.matcher(line).find()) { 92 log(i + 1, MSG_KEY, max, realLength); 93 } 94 } 95 } 96 97 /** 98 * Setter to specify the maximum line length allowed. 99 * 100 * @param length the maximum length of a line 101 * @since 3.0 102 */ 103 public void setMax(int length) { 104 max = length; 105 } 106 107 /** 108 * Setter to specify pattern for lines to ignore. 109 * 110 * @param pattern a pattern. 111 * @since 3.0 112 */ 113 public final void setIgnorePattern(Pattern pattern) { 114 ignorePattern = pattern; 115 } 116 117 /** 118 * Setter to specify the file extensions of the files to process. 119 * 120 * @param extensions the set of file extensions. A missing 121 * initial '.' character of an extension is automatically added. 122 * @throws IllegalArgumentException is argument is null 123 * @propertySince 8.24 124 */ 125 @Override 126 public final void setFileExtensions(String... extensions) { 127 super.setFileExtensions(extensions); 128 } 129 130 }