001///////////////////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
003// Copyright (C) 2001-2023 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.HashSet;
025import java.util.Set;
026import java.util.stream.Collectors;
027
028import com.puppycrawl.tools.checkstyle.StatelessCheck;
029import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
030import com.puppycrawl.tools.checkstyle.api.DetailAST;
031import com.puppycrawl.tools.checkstyle.api.FullIdent;
032import com.puppycrawl.tools.checkstyle.api.TokenTypes;
033import com.puppycrawl.tools.checkstyle.utils.AnnotationUtil;
034import com.puppycrawl.tools.checkstyle.utils.CheckUtil;
035
036/**
037 * <p>
038 * Checks that specified types are not declared to be thrown.
039 * Declaring that a method throws {@code java.lang.Error} or
040 * {@code java.lang.RuntimeException} is almost never acceptable.
041 * </p>
042 * <ul>
043 * <li>
044 * Property {@code illegalClassNames} - Specify throw class names to reject.
045 * Type is {@code java.lang.String[]}.
046 * Default value is {@code Error, RuntimeException, Throwable, java.lang.Error,
047 * java.lang.RuntimeException, java.lang.Throwable}.
048 * </li>
049 * <li>
050 * Property {@code ignoredMethodNames} - Specify names of methods to ignore.
051 * Type is {@code java.lang.String[]}.
052 * Default value is {@code finalize}.
053 * </li>
054 * <li>
055 * Property {@code ignoreOverriddenMethods} - allow to ignore checking overridden methods
056 * (marked with {@code Override} or {@code java.lang.Override} annotation).
057 * Type is {@code boolean}.
058 * Default value is {@code true}.
059 * </li>
060 * </ul>
061 * <p>
062 * To configure the check:
063 * </p>
064 * <pre>
065 * &lt;module name="IllegalThrows"/&gt;
066 * </pre>
067 * <p>Example:</p>
068 * <pre>
069 * public class Test {
070 *   public void func1() throws RuntimeException {} // violation
071 *   public void func2() throws Exception {}  // ok
072 *   public void func3() throws Error {}  // violation
073 *   public void func4() throws Throwable {} // violation
074 *   public void func5() throws NullPointerException {} // ok
075 *   &#064;Override
076 *   public void toString() throws Error {} // ok
077 * }
078 * </pre>
079 * <p>
080 * To configure the check rejecting throws NullPointerException from methods:
081 * </p>
082 * <pre>
083 * &lt;module name="IllegalThrows"&gt;
084 *   &lt;property name="illegalClassNames" value="NullPointerException"/&gt;
085 * &lt;/module&gt;
086 * </pre>
087 * <p>Example:</p>
088 * <pre>
089 * public class Test {
090 *   public void func1() throws RuntimeException {} // ok
091 *   public void func2() throws Exception {}  // ok
092 *   public void func3() throws Error {}  // ok
093 *   public void func4() throws Throwable {} // ok
094 *   public void func5() throws NullPointerException {} // violation
095 *   &#064;Override
096 *   public void toString() throws Error {} // ok
097 * }
098 * </pre>
099 * <p>
100 * To configure the check ignoring method named "func1()":
101 * </p>
102 * <pre>
103 * &lt;module name="IllegalThrows"&gt;
104 *   &lt;property name="ignoredMethodNames" value="func1"/&gt;
105 * &lt;/module&gt;
106 * </pre>
107 * <p>Example:</p>
108 * <pre>
109 * public class Test {
110 *   public void func1() throws RuntimeException {} // ok
111 *   public void func2() throws Exception {}  // ok
112 *   public void func3() throws Error {}  // violation
113 *   public void func4() throws Throwable {} // violation
114 *   public void func5() throws NullPointerException {} // ok
115 *   &#064;Override
116 *   public void toString() throws Error {} // ok
117 * }
118 * </pre>
119 * <p>
120 * To configure the check to warn on overridden methods:
121 * </p>
122 * <pre>
123 * &lt;module name=&quot;IllegalThrows&quot;&gt;
124 *   &lt;property name=&quot;ignoreOverriddenMethods&quot; value=&quot;false&quot;/&gt;
125 * &lt;/module&gt;
126 * </pre>
127 * <p>Example:</p>
128 * <pre>
129 * public class Test {
130 *   public void func1() throws RuntimeException {} // violation
131 *   public void func2() throws Exception {}  // ok
132 *   public void func3() throws Error {}  // violation
133 *   public void func4() throws Throwable {} // violation
134 *   public void func5() throws NullPointerException {} // ok
135 *   &#064;Override
136 *   public void toString() throws Error {} // violation
137 * }
138 * </pre>
139 * <p>
140 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
141 * </p>
142 * <p>
143 * Violation Message Keys:
144 * </p>
145 * <ul>
146 * <li>
147 * {@code illegal.throw}
148 * </li>
149 * </ul>
150 *
151 * @since 4.0
152 */
153@StatelessCheck
154public final class IllegalThrowsCheck extends AbstractCheck {
155
156    /**
157     * A key is pointing to the warning message text in "messages.properties"
158     * file.
159     */
160    public static final String MSG_KEY = "illegal.throw";
161
162    /** Specify names of methods to ignore. */
163    private final Set<String> ignoredMethodNames =
164        Arrays.stream(new String[] {"finalize", }).collect(Collectors.toCollection(HashSet::new));
165
166    /** Specify throw class names to reject. */
167    private final Set<String> illegalClassNames = Arrays.stream(
168        new String[] {"Error", "RuntimeException", "Throwable", "java.lang.Error",
169                      "java.lang.RuntimeException", "java.lang.Throwable", })
170        .collect(Collectors.toCollection(HashSet::new));
171
172    /**
173     * Allow to ignore checking overridden methods (marked with {@code Override}
174     * or {@code java.lang.Override} annotation).
175     */
176    private boolean ignoreOverriddenMethods = true;
177
178    /**
179     * Setter to specify throw class names to reject.
180     *
181     * @param classNames
182     *            array of illegal exception classes
183     */
184    public void setIllegalClassNames(final String... classNames) {
185        illegalClassNames.clear();
186        illegalClassNames.addAll(
187                CheckUtil.parseClassNames(classNames));
188    }
189
190    @Override
191    public int[] getDefaultTokens() {
192        return getRequiredTokens();
193    }
194
195    @Override
196    public int[] getRequiredTokens() {
197        return new int[] {TokenTypes.LITERAL_THROWS};
198    }
199
200    @Override
201    public int[] getAcceptableTokens() {
202        return getRequiredTokens();
203    }
204
205    @Override
206    public void visitToken(DetailAST detailAST) {
207        final DetailAST methodDef = detailAST.getParent();
208        // Check if the method with the given name should be ignored.
209        if (!isIgnorableMethod(methodDef)) {
210            DetailAST token = detailAST.getFirstChild();
211            while (token != null) {
212                final FullIdent ident = FullIdent.createFullIdent(token);
213                final String identText = ident.getText();
214                if (illegalClassNames.contains(identText)) {
215                    log(token, MSG_KEY, identText);
216                }
217                token = token.getNextSibling();
218            }
219        }
220    }
221
222    /**
223     * Checks if current method is ignorable due to Check's properties.
224     *
225     * @param methodDef {@link TokenTypes#METHOD_DEF METHOD_DEF}
226     * @return true if method is ignorable.
227     */
228    private boolean isIgnorableMethod(DetailAST methodDef) {
229        return shouldIgnoreMethod(methodDef.findFirstToken(TokenTypes.IDENT).getText())
230            || ignoreOverriddenMethods
231               && AnnotationUtil.hasOverrideAnnotation(methodDef);
232    }
233
234    /**
235     * Check if the method is specified in the ignore method list.
236     *
237     * @param name the name to check
238     * @return whether the method with the passed name should be ignored
239     */
240    private boolean shouldIgnoreMethod(String name) {
241        return ignoredMethodNames.contains(name);
242    }
243
244    /**
245     * Setter to specify names of methods to ignore.
246     *
247     * @param methodNames array of ignored method names
248     */
249    public void setIgnoredMethodNames(String... methodNames) {
250        ignoredMethodNames.clear();
251        Collections.addAll(ignoredMethodNames, methodNames);
252    }
253
254    /**
255     * Setter to allow to ignore checking overridden methods
256     * (marked with {@code Override} or {@code java.lang.Override} annotation).
257     *
258     * @param ignoreOverriddenMethods Check's property.
259     */
260    public void setIgnoreOverriddenMethods(boolean ignoreOverriddenMethods) {
261        this.ignoreOverriddenMethods = ignoreOverriddenMethods;
262    }
263
264}