pmd: fix #254 False+ : UnusedImport with Javadoc @throws

pmd/etc/changelog.txt

@@ -16,6 +16,7 @@ New Java rule:
 
 ????? ??, 2013 - 5.0.4:
 
+Fixed bug  254: False+ : UnusedImport with Javadoc @throws
 Fixed bug 1080: net.sourceforge.pmd.cpd.CPDTest test failing
 Fixed bug 1081: Regression: CPD skipping all files when using relative paths
 Fixed bug 1082: CPD performance issue on larger projects

pmd/src/main/java/net/sourceforge/pmd/lang/java/rule/imports/UnusedImportsRule.java

@@ -50,6 +50,7 @@ public class UnusedImportsRule extends AbstractJavaRule {
      * {@linkplain  package.class#member  label}
      * {@link  package.class#member  label}
      * {@value  package.class#field}
+     * @throws package.class label
      */
     private static final Pattern SEE_PATTERN = Pattern.compile(
             "@see\\s+(\\p{Alpha}\\p{Alnum}*)[\\s#]");
@@ -60,7 +61,10 @@ public class UnusedImportsRule extends AbstractJavaRule {
     private static final Pattern VALUE_PATTERN = Pattern.compile(
             "\\{@value\\s+(\\p{Alpha}\\p{Alnum}*)[\\s#\\}]");
 
-    private static final Pattern[] PATTERNS = { SEE_PATTERN, LINK_PATTERNS, VALUE_PATTERN };
+    private static final Pattern THROWS_PATTERN = Pattern.compile(
+            "@throws\\s+(\\p{Alpha}\\p{Alnum}*)");
+
+    private static final Pattern[] PATTERNS = { SEE_PATTERN, LINK_PATTERNS, VALUE_PATTERN, THROWS_PATTERN };
 
     private void visitComments(ASTCompilationUnit node) {
         if (imports.isEmpty()) {

pmd/src/test/resources/net/sourceforge/pmd/lang/java/rule/imports/xml/UnusedImports.xml

@@ -225,11 +225,13 @@ import edu.umd.cs.findbugs.annotations.NonNull;
         <code><![CDATA[
 import java.util.ArrayList;
 import java.util.Collections;
+import java.util.NoSuchElementException;
 
 public class Test {
     /**
      * {@link ArrayList#add(Object)}
      * @see Collections
+     * @throws NoSuchElementException no such element
      */
     String[] getList() { }
 }

pmd/src/test/resources/net/sourceforge/pmd/lang/java/rule/typeresolution/xml/UnusedImports.xml

@@ -156,7 +156,7 @@ public class Foo {
     </test-code>
     <test-code>
         <description><![CDATA[
-imports used in javadoc comment
+imports used in javadoc comment, see also bug #254
         ]]></description>
         <expected-problems>0</expected-problems>
         <code><![CDATA[
@@ -164,12 +164,15 @@ import java.util.ArrayList;
 import java.util.Calendar;
 import java.util.List;
 import java.util.File;
+import java.util.NoSuchElementException;
+
 public class Foo {
     /**
      * {@linkplain  List list}
      * {@link  ArrayList  arraylist}
      * {@value  Calendar#DATE}
      * @see File
+     * @throws NoSuchElementException no such element
      */
      public void test() {}
 }