001////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code for adherence to a set of rules.
003// Copyright (C) 2001-2020 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 if call to superclass constructor without arguments is present.
030 * Such invocation is redundant because constructor body implicitly
031 * begins with a superclass constructor invocation {@code super();}
032 * See <a href="https://docs.oracle.com/javase/specs/jls/se13/html/jls-8.html#jls-8.8.7">
033 * specification</a> for detailed information.
034 * </p>
035 * <p>
036 * To configure the check:
037 * </p>
038 * <pre>
039 * &lt;module name=&quot;AvoidNoArgumentSuperConstructorCall&quot;/&gt;
040 * </pre>
041 * <p>
042 * Example of violations
043 * </p>
044 * <pre>
045 * class MyClass extends SomeOtherClass {
046 *     MyClass() {
047 *         super(); // violation
048 *     }
049 *
050 *     MyClass(int arg) {
051 *         super(arg); // OK, call with argument have to be explicit
052 *     }
053 *
054 *     MyClass(long arg) {
055 *         // OK, call is implicit
056 *     }
057 * }
058 * </pre>
059 *
060 * @since 8.29
061 */
062@StatelessCheck
063public final class AvoidNoArgumentSuperConstructorCallCheck extends AbstractCheck {
064
065    /**
066     * A key is pointing to the warning message text in "messages.properties"
067     * file.
068     */
069    public static final String MSG_CTOR = "super.constructor.call";
070
071    @Override
072    public int[] getDefaultTokens() {
073        return getRequiredTokens();
074    }
075
076    @Override
077    public int[] getAcceptableTokens() {
078        return getRequiredTokens();
079    }
080
081    @Override
082    public int[] getRequiredTokens() {
083        return new int[] {
084            TokenTypes.SUPER_CTOR_CALL,
085        };
086    }
087
088    @Override
089    public void visitToken(DetailAST ast) {
090        if (ast.getFirstChild().getType() == TokenTypes.LPAREN
091                && ast.findFirstToken(TokenTypes.ELIST).getChildCount() == 0) {
092            log(ast, MSG_CTOR);
093        }
094    }
095}