001//////////////////////////////////////////////////////////////////////////////// 002// checkstyle: Checks Java source code for adherence to a set of rules. 003// Copyright (C) 2001-2015 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.design; 021 022import java.util.ArrayDeque; 023import java.util.Deque; 024 025import com.puppycrawl.tools.checkstyle.api.Check; 026import com.puppycrawl.tools.checkstyle.api.DetailAST; 027import com.puppycrawl.tools.checkstyle.api.TokenTypes; 028import com.puppycrawl.tools.checkstyle.utils.ScopeUtils; 029 030/** 031 * <p> 032 * Checks that class which has only private ctors 033 * is declared as final. Doesn't check for classes nested in interfaces 034 * or annotations, as they are always <code>final</code> there. 035 * </p> 036 * <p> 037 * An example of how to configure the check is: 038 * </p> 039 * <pre> 040 * <module name="FinalClass"/> 041 * </pre> 042 * @author o_sukhodolsky 043 */ 044public class FinalClassCheck 045 extends Check { 046 047 /** 048 * A key is pointing to the warning message text in "messages.properties" 049 * file. 050 */ 051 public static final String MSG_KEY = "final.class"; 052 053 /** Keeps ClassDesc objects for stack of declared classes. */ 054 private final Deque<ClassDesc> classes = new ArrayDeque<>(); 055 056 @Override 057 public int[] getDefaultTokens() { 058 return getAcceptableTokens(); 059 } 060 061 @Override 062 public int[] getAcceptableTokens() { 063 return new int[]{TokenTypes.CLASS_DEF, TokenTypes.CTOR_DEF}; 064 } 065 066 @Override 067 public int[] getRequiredTokens() { 068 return getAcceptableTokens(); 069 } 070 071 @Override 072 public void visitToken(DetailAST ast) { 073 final DetailAST modifiers = ast.findFirstToken(TokenTypes.MODIFIERS); 074 075 if (ast.getType() == TokenTypes.CLASS_DEF) { 076 final boolean isFinal = modifiers.branchContains(TokenTypes.FINAL); 077 final boolean isAbstract = modifiers.branchContains(TokenTypes.ABSTRACT); 078 classes.push(new ClassDesc(isFinal, isAbstract)); 079 } 080 // ctors in enums don't matter 081 else if (!ScopeUtils.isInEnumBlock(ast)) { 082 final ClassDesc desc = classes.peek(); 083 if (modifiers.branchContains(TokenTypes.LITERAL_PRIVATE)) { 084 desc.reportPrivateCtor(); 085 } 086 else { 087 desc.reportNonPrivateCtor(); 088 } 089 } 090 } 091 092 @Override 093 public void leaveToken(DetailAST ast) { 094 if (ast.getType() != TokenTypes.CLASS_DEF) { 095 return; 096 } 097 098 final ClassDesc desc = classes.pop(); 099 if (!desc.isDeclaredAsFinal() 100 && !desc.isDeclaredAsAbstract() 101 && desc.isWithPrivateCtor() 102 && !desc.isWithNonPrivateCtor() 103 && !ScopeUtils.isInInterfaceOrAnnotationBlock(ast)) { 104 final String className = 105 ast.findFirstToken(TokenTypes.IDENT).getText(); 106 log(ast.getLineNo(), MSG_KEY, className); 107 } 108 } 109 110 /** Maintains information about class' ctors. */ 111 private static final class ClassDesc { 112 /** Is class declared as final. */ 113 private final boolean declaredAsFinal; 114 115 /** Is class declared as abstract. */ 116 private final boolean declaredAsAbstract; 117 118 /** Does class have non-private ctors. */ 119 private boolean withNonPrivateCtor; 120 121 /** Does class have private ctors. */ 122 private boolean withPrivateCtor; 123 124 /** 125 * Create a new ClassDesc instance. 126 * @param declaredAsFinal indicates if the 127 * class declared as final 128 * @param declaredAsAbstract indicates if the 129 * class declared as abstract 130 */ 131 ClassDesc(boolean declaredAsFinal, boolean declaredAsAbstract) { 132 this.declaredAsFinal = declaredAsFinal; 133 this.declaredAsAbstract = declaredAsAbstract; 134 } 135 136 /** Adds private ctor. */ 137 private void reportPrivateCtor() { 138 withPrivateCtor = true; 139 } 140 141 /** Adds non-private ctor. */ 142 private void reportNonPrivateCtor() { 143 withNonPrivateCtor = true; 144 } 145 146 /** 147 * Does class have private ctors. 148 * @return true if class has private ctors 149 */ 150 private boolean isWithPrivateCtor() { 151 return withPrivateCtor; 152 } 153 154 /** 155 * Does class have non-private ctors. 156 * @return true if class has non-private ctors 157 */ 158 private boolean isWithNonPrivateCtor() { 159 return withNonPrivateCtor; 160 } 161 162 /** 163 * Is class declared as final. 164 * @return true if class is declared as final 165 */ 166 private boolean isDeclaredAsFinal() { 167 return declaredAsFinal; 168 } 169 170 /** 171 * Is class declared as abstract. 172 * @return true if class is declared as final 173 */ 174 private boolean isDeclaredAsAbstract() { 175 return declaredAsAbstract; 176 } 177 } 178}