com.puppycrawl.tools.checkstyle.checks.coding.IllegalCatchCheck Maven / Gradle / Ivy

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Checkstyle is a development tool to help programmers write Java code that adheres to a coding standard
There is a newer version: 10.18.1
////////////////////////////////////////////////////////////////////////////////
// checkstyle: Checks Java source code for adherence to a set of rules.
// Copyright (C) 2001-2020 the original author or authors.
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
////////////////////////////////////////////////////////////////////////////////

package com.puppycrawl.tools.checkstyle.checks.coding;

import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;
import java.util.Set;
import java.util.stream.Collectors;

import com.puppycrawl.tools.checkstyle.StatelessCheck;
import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
import com.puppycrawl.tools.checkstyle.api.DetailAST;
import com.puppycrawl.tools.checkstyle.api.FullIdent;
import com.puppycrawl.tools.checkstyle.api.TokenTypes;
import com.puppycrawl.tools.checkstyle.utils.CheckUtil;

/**
 * 
 * Checks that certain exception types do not appear in a {@code catch} statement.
 * 
 * 
 * Rationale: catching {@code java.lang.Exception}, {@code java.lang.Error} or
 * {@code java.lang.RuntimeException} is almost never acceptable.
 * Novice developers often simply catch Exception in an attempt to handle
 * multiple exception classes. This unfortunately leads to code that inadvertently
 * catches {@code NullPointerException}, {@code OutOfMemoryError}, etc.
 * 
 * 
 * 
 * Property {@code illegalClassNames} - Specify exception class names to reject.
 * Default value is {@code Error, Exception, RuntimeException, Throwable, java.lang.Error,
 * java.lang.Exception, java.lang.RuntimeException, java.lang.Throwable}.
 * 
 * 
 * 
 * To configure the check:
 * 
 *  * <module name="IllegalCatch"/>
 * 
 *
 * @since 3.2
 */
@StatelessCheck
public final class IllegalCatchCheck extends AbstractCheck {

    /**
     * A key is pointing to the warning message text in "messages.properties"
     * file.
     */
    public static final String MSG_KEY = "illegal.catch";

    /** Specify exception class names to reject. */
    private final Set illegalClassNames = Arrays.stream(new String[] {"Exception", "Error",
        "RuntimeException", "Throwable", "java.lang.Error", "java.lang.Exception",
        "java.lang.RuntimeException", "java.lang.Throwable", }).collect(Collectors.toSet());

    /**
     * Setter to specify exception class names to reject.
     *
     * @param classNames
     *            array of illegal exception classes
     */
    public void setIllegalClassNames(final String... classNames) {
        illegalClassNames.clear();
        illegalClassNames.addAll(
                CheckUtil.parseClassNames(classNames));
    }

    @Override
    public int[] getDefaultTokens() {
        return getRequiredTokens();
    }

    @Override
    public int[] getRequiredTokens() {
        return new int[] {TokenTypes.LITERAL_CATCH};
    }

    @Override
    public int[] getAcceptableTokens() {
        return getRequiredTokens();
    }

    @Override
    public void visitToken(DetailAST detailAST) {
        final DetailAST parameterDef =
            detailAST.findFirstToken(TokenTypes.PARAMETER_DEF);
        final DetailAST excTypeParent =
                parameterDef.findFirstToken(TokenTypes.TYPE);
        final List excTypes = getAllExceptionTypes(excTypeParent);

        for (DetailAST excType : excTypes) {
            final FullIdent ident = FullIdent.createFullIdent(excType);

            if (illegalClassNames.contains(ident.getText())) {
                log(detailAST, MSG_KEY, ident.getText());
            }
        }
    }

    /**
     * Finds all exception types in current catch.
     * We need it till we can have few different exception types into one catch.
     * @param parentToken - parent node for types (TYPE or BOR)
     * @return list, that contains all exception types in current catch
     */
    private static List getAllExceptionTypes(DetailAST parentToken) {
        DetailAST currentNode = parentToken.getFirstChild();
        final List exceptionTypes = new LinkedList<>();
        if (currentNode.getType() == TokenTypes.BOR) {
            exceptionTypes.addAll(getAllExceptionTypes(currentNode));
            currentNode = currentNode.getNextSibling();
            exceptionTypes.add(currentNode);
        }
        else {
            do {
                exceptionTypes.add(currentNode);
                currentNode = currentNode.getNextSibling();
            } while (currentNode != null);
        }
        return exceptionTypes;
    }

}