001///////////////////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
003// Copyright (C) 2001-2026 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 * <div>
029 * Checks that there is no method {@code finalize} with zero parameters.
030 * </div>
031 *
032 * <p>
033 * See
034 * <a href="https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/lang/Object.html#finalize()">
035 * Object.finalize()</a>
036 * </p>
037 *
038 * <p>
039 * Rationale: Finalizers are unpredictable, often dangerous, and generally unnecessary.
040 * Their use can cause erratic behavior, poor performance, and portability problems.
041 * For more information for the finalize method and its issues, see Effective Java:
042 * Programming Language Guide Third Edition by Joshua Bloch, &#167;8.
043 * </p>
044 *
045 * @since 5.0
046 */
047@StatelessCheck
048public class NoFinalizerCheck extends AbstractCheck {
049
050    /**
051     * A key is pointing to the warning message text in "messages.properties" file.
052     */
053    public static final String MSG_KEY = "avoid.finalizer.method";
054
055    /**
056     * Creates a new {@code NoFinalizerCheck} instance.
057     */
058    public NoFinalizerCheck() {
059        // no code by default
060    }
061
062    @Override
063    public int[] getDefaultTokens() {
064        return getRequiredTokens();
065    }
066
067    @Override
068    public int[] getAcceptableTokens() {
069        return getRequiredTokens();
070    }
071
072    @Override
073    public int[] getRequiredTokens() {
074        return new int[] {TokenTypes.METHOD_DEF};
075    }
076
077    @Override
078    public void visitToken(DetailAST ast) {
079        final DetailAST mid = ast.findFirstToken(TokenTypes.IDENT);
080        final String name = mid.getText();
081
082        if ("finalize".equals(name)) {
083            final DetailAST params = ast.findFirstToken(TokenTypes.PARAMETERS);
084            final boolean hasEmptyParamList =
085                params.findFirstToken(TokenTypes.PARAMETER_DEF) == null;
086
087            if (hasEmptyParamList) {
088                log(ast, MSG_KEY);
089            }
090        }
091    }
092
093}