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; 026 027/** 028 * <p> 029 * Checks that there is no method {@code finalize} with zero parameters. 030 * </p> 031 * <p> 032 * See 033 * <a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/Object.html#finalize()"> 034 * Object.finalize()</a> 035 * </p> 036 * <p> 037 * Rationale: Finalizers are unpredictable, often dangerous, and generally unnecessary. 038 * Their use can cause erratic behavior, poor performance, and portability problems. 039 * For more information for the finalize method and its issues, see Effective Java: 040 * Programming Language Guide Third Edition by Joshua Bloch, §8. 041 * </p> 042 * <p> 043 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker} 044 * </p> 045 * <p> 046 * Violation Message Keys: 047 * </p> 048 * <ul> 049 * <li> 050 * {@code avoid.finalizer.method} 051 * </li> 052 * </ul> 053 * 054 * @since 5.0 055 */ 056@StatelessCheck 057public class NoFinalizerCheck extends AbstractCheck { 058 059 /** 060 * A key is pointing to the warning message text in "messages.properties" 061 * file. 062 */ 063 public static final String MSG_KEY = "avoid.finalizer.method"; 064 065 @Override 066 public int[] getDefaultTokens() { 067 return getRequiredTokens(); 068 } 069 070 @Override 071 public int[] getAcceptableTokens() { 072 return getRequiredTokens(); 073 } 074 075 @Override 076 public int[] getRequiredTokens() { 077 return new int[] {TokenTypes.METHOD_DEF}; 078 } 079 080 @Override 081 public void visitToken(DetailAST ast) { 082 final DetailAST mid = ast.findFirstToken(TokenTypes.IDENT); 083 final String name = mid.getText(); 084 085 if ("finalize".equals(name)) { 086 final DetailAST params = ast.findFirstToken(TokenTypes.PARAMETERS); 087 final boolean hasEmptyParamList = 088 params.findFirstToken(TokenTypes.PARAMETER_DEF) == null; 089 090 if (hasEmptyParamList) { 091 log(ast, MSG_KEY); 092 } 093 } 094 } 095 096}