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.coding; 021 022import com.puppycrawl.tools.checkstyle.StatelessCheck; 023import com.puppycrawl.tools.checkstyle.api.AbstractCheck; 024import com.puppycrawl.tools.checkstyle.api.DetailAST; 025import com.puppycrawl.tools.checkstyle.api.TokenTypes; 026import com.puppycrawl.tools.checkstyle.utils.TokenUtil; 027 028/** 029 * <div> 030 * Checks that enum definition does not contain a trailing comma. 031 * Rationale: JLS allows trailing commas in arrays and enumerations, but does not allow 032 * them in other locations. To unify the coding style, the use of trailing commas should 033 * be prohibited. 034 * </div> 035 * <pre> 036 * enum Foo1 { 037 * FOO, 038 * BAR; 039 * } 040 * </pre> 041 * 042 * <p> 043 * The check demands that there should not be any comma after last constant in 044 * enum definition. 045 * </p> 046 * <pre> 047 * enum Foo1 { 048 * FOO, 049 * BAR, //violation 050 * } 051 * </pre> 052 * 053 * <p> 054 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker} 055 * </p> 056 * 057 * <p> 058 * Violation Message Keys: 059 * </p> 060 * <ul> 061 * <li> 062 * {@code no.enum.trailing.comma} 063 * </li> 064 * </ul> 065 * 066 * @since 8.29 067 */ 068@StatelessCheck 069public class NoEnumTrailingCommaCheck extends AbstractCheck { 070 071 /** 072 * A key is pointing to the warning message text in "messages.properties" 073 * file. 074 */ 075 public static final String MSG_KEY = "no.enum.trailing.comma"; 076 077 @Override 078 public int[] getDefaultTokens() { 079 return getRequiredTokens(); 080 } 081 082 @Override 083 public int[] getAcceptableTokens() { 084 return getRequiredTokens(); 085 } 086 087 @Override 088 public int[] getRequiredTokens() { 089 return new int[] {TokenTypes.ENUM_DEF}; 090 } 091 092 @Override 093 public void visitToken(DetailAST detailAST) { 094 final DetailAST enumBlock = detailAST.findFirstToken(TokenTypes.OBJBLOCK); 095 TokenUtil.findFirstTokenByPredicate(enumBlock, 096 node -> TokenUtil.isOfType(node, TokenTypes.SEMI, TokenTypes.RCURLY)) 097 .map(DetailAST::getPreviousSibling) 098 .filter(token -> token.getType() == TokenTypes.COMMA) 099 .ifPresent(comma -> log(comma, MSG_KEY)); 100 } 101}