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 * <p> 032 * Checks for long lines. 033 * </p> 034 * <p> 035 * Rationale: Long lines are hard to read in printouts or if developers 036 * have limited screen space for the source code, e.g. if the IDE displays 037 * additional information like project tree, class hierarchy, etc. 038 * </p> 039 * <ul> 040 * <li> 041 * The calculation of the length of a line takes into account the number of 042 * expanded spaces for a tab character ({@code '\t'}). The default number of spaces is {@code 8}. 043 * To specify a different number of spaces, the user can set 044 * <a href="https://checkstyle.org/config.html#Checker">{@code Checker}</a> 045 * property {@code tabWidth} which applies to all Checks, including {@code LineLength}; 046 * or can set property {@code tabWidth} for {@code LineLength} alone. 047 * </li> 048 * <li> 049 * By default, package and import statements (lines matching pattern {@code ^(package|import) .*}) 050 * are not verified by this check. 051 * </li> 052 * <li> 053 * Trailing comments are taken into consideration while calculating the line length. 054 * <pre> 055 * import java.util.regex.Pattern; // The length of this comment will be taken into consideration 056 * </pre> 057 * In the example above the length of the import statement is just 31 characters but total length 058 * will be 94 characters. 059 * </li> 060 * </ul> 061 * <ul> 062 * <li> 063 * Property {@code fileExtensions} - Specify the file extensions of the files to process. 064 * Type is {@code java.lang.String[]}. 065 * Default value is {@code ""}. 066 * </li> 067 * <li> 068 * Property {@code ignorePattern} - Specify pattern for lines to ignore. 069 * Type is {@code java.util.regex.Pattern}. 070 * Default value is {@code "^(package|import) .*"}. 071 * </li> 072 * <li> 073 * Property {@code max} - Specify the maximum line length allowed. 074 * Type is {@code int}. 075 * Default value is {@code 80}. 076 * </li> 077 * </ul> 078 * <p> 079 * Parent is {@code com.puppycrawl.tools.checkstyle.Checker} 080 * </p> 081 * <p> 082 * Violation Message Keys: 083 * </p> 084 * <ul> 085 * <li> 086 * {@code maxLineLen} 087 * </li> 088 * </ul> 089 * 090 * @since 3.0 091 */ 092@StatelessCheck 093public class LineLengthCheck extends AbstractFileSetCheck { 094 095 /** 096 * A key is pointing to the warning message text in "messages.properties" 097 * file. 098 */ 099 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}