1 /////////////////////////////////////////////////////////////////////////////////////////////// 2 // checkstyle: Checks Java source code and other text files for adherence to a set of rules. 3 // Copyright (C) 2001-2024 the original author or authors. 4 // 5 // This library is free software; you can redistribute it and/or 6 // modify it under the terms of the GNU Lesser General Public 7 // License as published by the Free Software Foundation; either 8 // version 2.1 of the License, or (at your option) any later version. 9 // 10 // This library is distributed in the hope that it will be useful, 11 // but WITHOUT ANY WARRANTY; without even the implied warranty of 12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 13 // Lesser General Public License for more details. 14 // 15 // You should have received a copy of the GNU Lesser General Public 16 // License along with this library; if not, write to the Free Software 17 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 18 /////////////////////////////////////////////////////////////////////////////////////////////// 19 20 package com.puppycrawl.tools.checkstyle.checks.coding; 21 22 import com.puppycrawl.tools.checkstyle.StatelessCheck; 23 import com.puppycrawl.tools.checkstyle.api.AbstractCheck; 24 import com.puppycrawl.tools.checkstyle.api.DetailAST; 25 import com.puppycrawl.tools.checkstyle.api.TokenTypes; 26 27 /** 28 * <p> 29 * Checks that there is no method {@code finalize} with zero parameters. 30 * </p> 31 * <p> 32 * See 33 * <a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/Object.html#finalize()"> 34 * Object.finalize()</a> 35 * </p> 36 * <p> 37 * Rationale: Finalizers are unpredictable, often dangerous, and generally unnecessary. 38 * Their use can cause erratic behavior, poor performance, and portability problems. 39 * For more information for the finalize method and its issues, see Effective Java: 40 * Programming Language Guide Third Edition by Joshua Bloch, §8. 41 * </p> 42 * <p> 43 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker} 44 * </p> 45 * <p> 46 * Violation Message Keys: 47 * </p> 48 * <ul> 49 * <li> 50 * {@code avoid.finalizer.method} 51 * </li> 52 * </ul> 53 * 54 * @since 5.0 55 */ 56 @StatelessCheck 57 public class NoFinalizerCheck extends AbstractCheck { 58 59 /** 60 * A key is pointing to the warning message text in "messages.properties" 61 * file. 62 */ 63 public static final String MSG_KEY = "avoid.finalizer.method"; 64 65 @Override 66 public int[] getDefaultTokens() { 67 return getRequiredTokens(); 68 } 69 70 @Override 71 public int[] getAcceptableTokens() { 72 return getRequiredTokens(); 73 } 74 75 @Override 76 public int[] getRequiredTokens() { 77 return new int[] {TokenTypes.METHOD_DEF}; 78 } 79 80 @Override 81 public void visitToken(DetailAST ast) { 82 final DetailAST mid = ast.findFirstToken(TokenTypes.IDENT); 83 final String name = mid.getText(); 84 85 if ("finalize".equals(name)) { 86 final DetailAST params = ast.findFirstToken(TokenTypes.PARAMETERS); 87 final boolean hasEmptyParamList = 88 params.findFirstToken(TokenTypes.PARAMETER_DEF) == null; 89 90 if (hasEmptyParamList) { 91 log(ast, MSG_KEY); 92 } 93 } 94 } 95 96 }