1 ///////////////////////////////////////////////////////////////////////////////////////////////
2 // checkstyle: Checks Java source code and other text files for adherence to a set of rules.
3 // Copyright (C) 2001-2025 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/11/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 * <p>
46 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
47 * </p>
48 *
49 * <p>
50 * Violation Message Keys:
51 * </p>
52 * <ul>
53 * <li>
54 * {@code avoid.finalizer.method}
55 * </li>
56 * </ul>
57 *
58 * @since 5.0
59 */
60 @StatelessCheck
61 public class NoFinalizerCheck extends AbstractCheck {
62
63 /**
64 * A key is pointing to the warning message text in "messages.properties"
65 * file.
66 */
67 public static final String MSG_KEY = "avoid.finalizer.method";
68
69 @Override
70 public int[] getDefaultTokens() {
71 return getRequiredTokens();
72 }
73
74 @Override
75 public int[] getAcceptableTokens() {
76 return getRequiredTokens();
77 }
78
79 @Override
80 public int[] getRequiredTokens() {
81 return new int[] {TokenTypes.METHOD_DEF};
82 }
83
84 @Override
85 public void visitToken(DetailAST ast) {
86 final DetailAST mid = ast.findFirstToken(TokenTypes.IDENT);
87 final String name = mid.getText();
88
89 if ("finalize".equals(name)) {
90 final DetailAST params = ast.findFirstToken(TokenTypes.PARAMETERS);
91 final boolean hasEmptyParamList =
92 params.findFirstToken(TokenTypes.PARAMETER_DEF) == null;
93
94 if (hasEmptyParamList) {
95 log(ast, MSG_KEY);
96 }
97 }
98 }
99
100 }