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 java.util.Arrays;
023import java.util.Collections;
024import java.util.Set;
025import java.util.stream.Collectors;
026
027import com.puppycrawl.tools.checkstyle.StatelessCheck;
028import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
029import com.puppycrawl.tools.checkstyle.api.DetailAST;
030import com.puppycrawl.tools.checkstyle.api.FullIdent;
031import com.puppycrawl.tools.checkstyle.api.TokenTypes;
032import com.puppycrawl.tools.checkstyle.utils.AnnotationUtil;
033import com.puppycrawl.tools.checkstyle.utils.CheckUtil;
034
035/**
036 * <p>
037 * Checks that specified types are not declared to be thrown.
038 * Declaring that a method throws {@code java.lang.Error} or
039 * {@code java.lang.RuntimeException} is almost never acceptable.
040 * </p>
041 * <ul>
042 * <li>
043 * Property {@code illegalClassNames} - Specify throw class names to reject.
044 * Default value is {@code Error, RuntimeException, Throwable, java.lang.Error,
045 * java.lang.RuntimeException, java.lang.Throwable}.
046 * </li>
047 * <li>
048 * Property {@code ignoredMethodNames} - Specify names of methods to ignore.
049 * Default value is {@code finalize}.
050 * </li>
051 * <li>
052 * Property {@code ignoreOverriddenMethods} - allow to ignore checking overridden methods
053 * (marked with {@code Override} or {@code java.lang.Override} annotation).
054 * Default value is {@code true}.
055 * </li>
056 * </ul>
057 * <p>
058 * To configure the check:
059 * </p>
060 * <pre>
061 * &lt;module name="IllegalThrows"/&gt;
062 * </pre>
063 * <p>
064 * To configure the check rejecting throws NullPointerException from methods:
065 * </p>
066 * <pre>
067 * &lt;module name="IllegalThrows"&gt;
068 *   &lt;property name="illegalClassNames" value="NullPointerException"/&gt;
069 * &lt;/module&gt;
070 * </pre>
071 * <p>
072 * To configure the check ignoring method named "foo()":
073 * </p>
074 * <pre>
075 * &lt;module name="IllegalThrows"&gt;
076 *   &lt;property name="ignoredMethodNames" value="foo"/&gt;
077 * &lt;/module&gt;
078 * </pre>
079 * <p>
080 * To configure the check to warn on overridden methods:
081 * </p>
082 * <pre>
083 * &lt;module name=&quot;IllegalThrows&quot;&gt;
084 *   &lt;property name=&quot;ignoreOverriddenMethods&quot; value=&quot;false&quot;/&gt;
085 * &lt;/module&gt;
086 * </pre>
087 *
088 * @since 4.0
089 */
090@StatelessCheck
091public final class IllegalThrowsCheck extends AbstractCheck {
092
093    /**
094     * A key is pointing to the warning message text in "messages.properties"
095     * file.
096     */
097    public static final String MSG_KEY = "illegal.throw";
098
099    /** Specify names of methods to ignore. */
100    private final Set<String> ignoredMethodNames =
101        Arrays.stream(new String[] {"finalize", }).collect(Collectors.toSet());
102
103    /** Specify throw class names to reject. */
104    private final Set<String> illegalClassNames = Arrays.stream(
105        new String[] {"Error", "RuntimeException", "Throwable", "java.lang.Error",
106                      "java.lang.RuntimeException", "java.lang.Throwable", })
107        .collect(Collectors.toSet());
108
109    /**
110     * Allow to ignore checking overridden methods (marked with {@code Override}
111     * or {@code java.lang.Override} annotation).
112     */
113    private boolean ignoreOverriddenMethods = true;
114
115    /**
116     * Setter to specify throw class names to reject.
117     *
118     * @param classNames
119     *            array of illegal exception classes
120     */
121    public void setIllegalClassNames(final String... classNames) {
122        illegalClassNames.clear();
123        illegalClassNames.addAll(
124                CheckUtil.parseClassNames(classNames));
125    }
126
127    @Override
128    public int[] getDefaultTokens() {
129        return getRequiredTokens();
130    }
131
132    @Override
133    public int[] getRequiredTokens() {
134        return new int[] {TokenTypes.LITERAL_THROWS};
135    }
136
137    @Override
138    public int[] getAcceptableTokens() {
139        return getRequiredTokens();
140    }
141
142    @Override
143    public void visitToken(DetailAST detailAST) {
144        final DetailAST methodDef = detailAST.getParent();
145        // Check if the method with the given name should be ignored.
146        if (!isIgnorableMethod(methodDef)) {
147            DetailAST token = detailAST.getFirstChild();
148            while (token != null) {
149                final FullIdent ident = FullIdent.createFullIdent(token);
150                if (illegalClassNames.contains(ident.getText())) {
151                    log(token, MSG_KEY, ident.getText());
152                }
153                token = token.getNextSibling();
154            }
155        }
156    }
157
158    /**
159     * Checks if current method is ignorable due to Check's properties.
160     * @param methodDef {@link TokenTypes#METHOD_DEF METHOD_DEF}
161     * @return true if method is ignorable.
162     */
163    private boolean isIgnorableMethod(DetailAST methodDef) {
164        return shouldIgnoreMethod(methodDef.findFirstToken(TokenTypes.IDENT).getText())
165            || ignoreOverriddenMethods
166               && (AnnotationUtil.containsAnnotation(methodDef, "Override")
167                  || AnnotationUtil.containsAnnotation(methodDef, "java.lang.Override"));
168    }
169
170    /**
171     * Check if the method is specified in the ignore method list.
172     * @param name the name to check
173     * @return whether the method with the passed name should be ignored
174     */
175    private boolean shouldIgnoreMethod(String name) {
176        return ignoredMethodNames.contains(name);
177    }
178
179    /**
180     * Setter to specify names of methods to ignore.
181     * @param methodNames array of ignored method names
182     */
183    public void setIgnoredMethodNames(String... methodNames) {
184        ignoredMethodNames.clear();
185        Collections.addAll(ignoredMethodNames, methodNames);
186    }
187
188    /**
189     * Setter to allow to ignore checking overridden methods
190     * (marked with {@code Override} or {@code java.lang.Override} annotation).
191     * @param ignoreOverriddenMethods Check's property.
192     */
193    public void setIgnoreOverriddenMethods(boolean ignoreOverriddenMethods) {
194        this.ignoreOverriddenMethods = ignoreOverriddenMethods;
195    }
196
197}