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 classes (except abstract ones) define a constructor and don't rely
030 * on the default one.
031 * </div>
032 *
033 * <p>
034 * Compatibility note: <b>when creating</b> an explicit constructor already
035 * in existing class that used by other in codebases that you do not own, it must match
036 * precisely the declaration of the automatically generated constructor;
037 * even if the constructor should logically be protected, it must be made
038 * public to match the declaration of the automatically generated
039 * constructor, for <b>compatibility</b>.
040 * </p>
041 *
042 * <p>
043 * See
044 * <a href="https://www.oracle.com/technical-resources/articles/java/javadoc-tool.html#defaultconstructors">
045 * Documentation Comments Style Guide</a>.
046 * </p>
047 *
048 * @since 3.4
049 */
050@StatelessCheck
051public class MissingCtorCheck extends AbstractCheck {
052
053    /**
054     * A key is pointing to the warning message text in "messages.properties" file.
055     */
056    public static final String MSG_KEY = "missing.ctor";
057
058    /**
059     * Creates a new {@code MissingCtorCheck} instance.
060     */
061    public MissingCtorCheck() {
062        // no code by default
063    }
064
065    @Override
066    public int[] getDefaultTokens() {
067        return getRequiredTokens();
068    }
069
070    @Override
071    public int[] getAcceptableTokens() {
072        return getRequiredTokens();
073    }
074
075    @Override
076    public int[] getRequiredTokens() {
077        return new int[] {TokenTypes.CLASS_DEF};
078    }
079
080    @Override
081    public void visitToken(DetailAST ast) {
082        final DetailAST modifiers = ast.findFirstToken(TokenTypes.MODIFIERS);
083        if (modifiers.findFirstToken(TokenTypes.ABSTRACT) == null
084                && ast.findFirstToken(TokenTypes.OBJBLOCK)
085                    .findFirstToken(TokenTypes.CTOR_DEF) == null) {
086            log(ast, MSG_KEY);
087        }
088    }
089
090}