001/////////////////////////////////////////////////////////////////////////////////////////////// 002// checkstyle: Checks Java source code and other text files for adherence to a set of rules. 003// Copyright (C) 2001-2024 the original author or authors. 004// 005// This library is free software; you can redistribute it and/or 006// modify it under the terms of the GNU Lesser General Public 007// License as published by the Free Software Foundation; either 008// version 2.1 of the License, or (at your option) any later version. 009// 010// This library is distributed in the hope that it will be useful, 011// but WITHOUT ANY WARRANTY; without even the implied warranty of 012// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 013// Lesser General Public License for more details. 014// 015// You should have received a copy of the GNU Lesser General Public 016// License along with this library; if not, write to the Free Software 017// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 018/////////////////////////////////////////////////////////////////////////////////////////////// 019 020package com.puppycrawl.tools.checkstyle.checks.sizes; 021 022import java.io.File; 023import java.util.regex.Pattern; 024 025import com.puppycrawl.tools.checkstyle.StatelessCheck; 026import com.puppycrawl.tools.checkstyle.api.AbstractFileSetCheck; 027import com.puppycrawl.tools.checkstyle.api.FileText; 028import com.puppycrawl.tools.checkstyle.utils.CommonUtil; 029 030/** 031 * <div> 032 * Checks for long lines. 033 * </div> 034 * 035 * <p> 036 * Rationale: Long lines are hard to read in printouts or if developers 037 * have limited screen space for the source code, e.g. if the IDE displays 038 * additional information like project tree, class hierarchy, etc. 039 * </p> 040 * <ul> 041 * <li> 042 * The calculation of the length of a line takes into account the number of 043 * expanded spaces for a tab character ({@code '\t'}). The default number of spaces is {@code 8}. 044 * To specify a different number of spaces, the user can set 045 * <a href="https://checkstyle.org/config.html#Checker">{@code Checker}</a> 046 * property {@code tabWidth} which applies to all Checks, including {@code LineLength}; 047 * or can set property {@code tabWidth} for {@code LineLength} alone. 048 * </li> 049 * <li> 050 * By default, package and import statements (lines matching pattern {@code ^(package|import) .*}) 051 * are not verified by this check. 052 * </li> 053 * <li> 054 * Trailing comments are taken into consideration while calculating the line length. 055 * <pre> 056 * import java.util.regex.Pattern; // The length of this comment will be taken into consideration 057 * </pre> 058 * In the example above the length of the import statement is just 31 characters but total length 059 * will be 94 characters. 060 * </li> 061 * </ul> 062 * <ul> 063 * <li> 064 * Property {@code fileExtensions} - Specify the file extensions of the files to process. 065 * Type is {@code java.lang.String[]}. 066 * Default value is {@code ""}. 067 * </li> 068 * <li> 069 * Property {@code ignorePattern} - Specify pattern for lines to ignore. 070 * Type is {@code java.util.regex.Pattern}. 071 * Default value is {@code "^(package|import) .*"}. 072 * </li> 073 * <li> 074 * Property {@code max} - Specify the maximum line length allowed. 075 * Type is {@code int}. 076 * Default value is {@code 80}. 077 * </li> 078 * </ul> 079 * 080 * <p> 081 * Parent is {@code com.puppycrawl.tools.checkstyle.Checker} 082 * </p> 083 * 084 * <p> 085 * Violation Message Keys: 086 * </p> 087 * <ul> 088 * <li> 089 * {@code maxLineLen} 090 * </li> 091 * </ul> 092 * 093 * @since 3.0 094 */ 095@StatelessCheck 096public class LineLengthCheck extends AbstractFileSetCheck { 097 098 /** 099 * A key is pointing to the warning message text in "messages.properties" 100 * file. 101 */ 102 public static final String MSG_KEY = "maxLineLen"; 103 104 /** Default maximum number of columns in a line. */ 105 private static final int DEFAULT_MAX_COLUMNS = 80; 106 107 /** Specify the maximum line length allowed. */ 108 private int max = DEFAULT_MAX_COLUMNS; 109 110 /** Specify pattern for lines to ignore. */ 111 private Pattern ignorePattern = Pattern.compile("^(package|import) .*"); 112 113 @Override 114 protected void processFiltered(File file, FileText fileText) { 115 for (int i = 0; i < fileText.size(); i++) { 116 final String line = fileText.get(i); 117 final int realLength = CommonUtil.lengthExpandedTabs( 118 line, line.codePointCount(0, line.length()), getTabWidth()); 119 120 if (realLength > max && !ignorePattern.matcher(line).find()) { 121 log(i + 1, MSG_KEY, max, realLength); 122 } 123 } 124 } 125 126 /** 127 * Setter to specify the maximum line length allowed. 128 * 129 * @param length the maximum length of a line 130 * @since 3.0 131 */ 132 public void setMax(int length) { 133 max = length; 134 } 135 136 /** 137 * Setter to specify pattern for lines to ignore. 138 * 139 * @param pattern a pattern. 140 * @since 3.0 141 */ 142 public final void setIgnorePattern(Pattern pattern) { 143 ignorePattern = pattern; 144 } 145 146}