1 /////////////////////////////////////////////////////////////////////////////////////////////// 2 // checkstyle: Checks Java source code and other text files for adherence to a set of rules. 3 // Copyright (C) 2001-2024 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 * <p> 32 * Checks for long lines. 33 * </p> 34 * <p> 35 * Rationale: Long lines are hard to read in printouts or if developers 36 * have limited screen space for the source code, e.g. if the IDE displays 37 * additional information like project tree, class hierarchy, etc. 38 * </p> 39 * <ul> 40 * <li> 41 * The calculation of the length of a line takes into account the number of 42 * expanded spaces for a tab character ({@code '\t'}). The default number of spaces is {@code 8}. 43 * To specify a different number of spaces, the user can set 44 * <a href="https://checkstyle.org/config.html#Checker">{@code Checker}</a> 45 * property {@code tabWidth} which applies to all Checks, including {@code LineLength}; 46 * or can set property {@code tabWidth} for {@code LineLength} alone. 47 * </li> 48 * <li> 49 * By default, package and import statements (lines matching pattern {@code ^(package|import) .*}) 50 * are not verified by this check. 51 * </li> 52 * <li> 53 * Trailing comments are taken into consideration while calculating the line length. 54 * <pre> 55 * import java.util.regex.Pattern; // The length of this comment will be taken into consideration 56 * </pre> 57 * In the example above the length of the import statement is just 31 characters but total length 58 * will be 94 characters. 59 * </li> 60 * </ul> 61 * <ul> 62 * <li> 63 * Property {@code fileExtensions} - Specify the file extensions of the files to process. 64 * Type is {@code java.lang.String[]}. 65 * Default value is {@code ""}. 66 * </li> 67 * <li> 68 * Property {@code ignorePattern} - Specify pattern for lines to ignore. 69 * Type is {@code java.util.regex.Pattern}. 70 * Default value is {@code "^(package|import) .*"}. 71 * </li> 72 * <li> 73 * Property {@code max} - Specify the maximum line length allowed. 74 * Type is {@code int}. 75 * Default value is {@code 80}. 76 * </li> 77 * </ul> 78 * <p> 79 * Parent is {@code com.puppycrawl.tools.checkstyle.Checker} 80 * </p> 81 * <p> 82 * Violation Message Keys: 83 * </p> 84 * <ul> 85 * <li> 86 * {@code maxLineLen} 87 * </li> 88 * </ul> 89 * 90 * @since 3.0 91 */ 92 @StatelessCheck 93 public class LineLengthCheck extends AbstractFileSetCheck { 94 95 /** 96 * A key is pointing to the warning message text in "messages.properties" 97 * file. 98 */ 99 public static final String MSG_KEY = "maxLineLen"; 100 101 /** Default maximum number of columns in a line. */ 102 private static final int DEFAULT_MAX_COLUMNS = 80; 103 104 /** Specify the maximum line length allowed. */ 105 private int max = DEFAULT_MAX_COLUMNS; 106 107 /** Specify pattern for lines to ignore. */ 108 private Pattern ignorePattern = Pattern.compile("^(package|import) .*"); 109 110 @Override 111 protected void processFiltered(File file, FileText fileText) { 112 for (int i = 0; i < fileText.size(); i++) { 113 final String line = fileText.get(i); 114 final int realLength = CommonUtil.lengthExpandedTabs( 115 line, line.codePointCount(0, line.length()), getTabWidth()); 116 117 if (realLength > max && !ignorePattern.matcher(line).find()) { 118 log(i + 1, MSG_KEY, max, realLength); 119 } 120 } 121 } 122 123 /** 124 * Setter to specify the maximum line length allowed. 125 * 126 * @param length the maximum length of a line 127 * @since 3.0 128 */ 129 public void setMax(int length) { 130 max = length; 131 } 132 133 /** 134 * Setter to specify pattern for lines to ignore. 135 * 136 * @param pattern a pattern. 137 * @since 3.0 138 */ 139 public final void setIgnorePattern(Pattern pattern) { 140 ignorePattern = pattern; 141 } 142 143 }