001////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code for adherence to a set of rules.
003// Copyright (C) 2001-2021 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 * <p>
029 * Checks that classes (except abstract ones) define a constructor and don't rely
030 * on the default one.
031 * </p>
032 * <p>
033 * To configure the check:
034 * </p>
035 * <pre>
036 * &lt;module name=&quot;MissingCtor&quot;/&gt;
037 * </pre>
038 * <p>Example:</p>
039 * <pre>
040 * class ExampleOk { // OK
041 *   private int a;
042 *   ExampleOk(int a) {
043 *     this.a = a;
044 *   }
045 * }
046 * class ExampleDefaultCtor { // OK
047 *   private String s;
048 *   ExampleDefaultCtor() {
049 *     s = "foobar";
050 *   }
051 * }
052 * class InvalidExample { // violation, class must have a constructor.
053 *   public void test() {}
054 * }
055 * abstract class AbstractExample { // OK
056 *   public abstract void test() {}
057 * }
058 * </pre>
059 * <p>
060 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
061 * </p>
062 * <p>
063 * Violation Message Keys:
064 * </p>
065 * <ul>
066 * <li>
067 * {@code missing.ctor}
068 * </li>
069 * </ul>
070 *
071 * @since 3.4
072 */
073@StatelessCheck
074public class MissingCtorCheck extends AbstractCheck {
075
076    /**
077     * A key is pointing to the warning message text in "messages.properties"
078     * file.
079     */
080    public static final String MSG_KEY = "missing.ctor";
081
082    @Override
083    public int[] getDefaultTokens() {
084        return getRequiredTokens();
085    }
086
087    @Override
088    public int[] getAcceptableTokens() {
089        return getRequiredTokens();
090    }
091
092    @Override
093    public int[] getRequiredTokens() {
094        return new int[] {TokenTypes.CLASS_DEF};
095    }
096
097    @Override
098    public void visitToken(DetailAST ast) {
099        final DetailAST modifiers = ast.findFirstToken(TokenTypes.MODIFIERS);
100        if (modifiers.findFirstToken(TokenTypes.ABSTRACT) == null
101                && ast.findFirstToken(TokenTypes.OBJBLOCK)
102                    .findFirstToken(TokenTypes.CTOR_DEF) == null) {
103            log(ast, MSG_KEY);
104        }
105    }
106
107}