1 ///////////////////////////////////////////////////////////////////////////////////////////////
2 // checkstyle: Checks Java source code and other text files for adherence to a set of rules.
3 // Copyright (C) 2001-2026 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 * <div>
29 * Checks that there is no method {@code finalize} with zero parameters.
30 * </div>
31 *
32 * <p>
33 * See
34 * <a href="https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/lang/Object.html#finalize()">
35 * Object.finalize()</a>
36 * </p>
37 *
38 * <p>
39 * Rationale: Finalizers are unpredictable, often dangerous, and generally unnecessary.
40 * Their use can cause erratic behavior, poor performance, and portability problems.
41 * For more information for the finalize method and its issues, see Effective Java:
42 * Programming Language Guide Third Edition by Joshua Bloch, §8.
43 * </p>
44 *
45 * @since 5.0
46 */
47 @StatelessCheck
48 public class NoFinalizerCheck extends AbstractCheck {
49
50 /**
51 * A key is pointing to the warning message text in "messages.properties"
52 * file.
53 */
54 public static final String MSG_KEY = "avoid.finalizer.method";
55
56 /**
57 * Creates a new {@code NoFinalizerCheck} instance.
58 */
59 public NoFinalizerCheck() {
60 // no code by default
61 }
62
63 @Override
64 public int[] getDefaultTokens() {
65 return getRequiredTokens();
66 }
67
68 @Override
69 public int[] getAcceptableTokens() {
70 return getRequiredTokens();
71 }
72
73 @Override
74 public int[] getRequiredTokens() {
75 return new int[] {TokenTypes.METHOD_DEF};
76 }
77
78 @Override
79 public void visitToken(DetailAST ast) {
80 final DetailAST mid = ast.findFirstToken(TokenTypes.IDENT);
81 final String name = mid.getText();
82
83 if ("finalize".equals(name)) {
84 final DetailAST params = ast.findFirstToken(TokenTypes.PARAMETERS);
85 final boolean hasEmptyParamList =
86 params.findFirstToken(TokenTypes.PARAMETER_DEF) == null;
87
88 if (hasEmptyParamList) {
89 log(ast, MSG_KEY);
90 }
91 }
92 }
93
94 }