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 }