[java] MissingOverrideRule exception when analyzing PMD under Java 9

Adds a workaround, that fixes pmd#1074
adangel · Jun 18, 2018 · d6dbfa6 · d6dbfa6
1 parent e1066fe
commit d6dbfa6
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Showing 2 changed files with 21 additions and 2 deletions.
diff --git a/docs/pages/release_notes.md b/docs/pages/release_notes.md
@@ -34,6 +34,8 @@ This is a minor release.
     *   [#1193](https://github.com/pmd/pmd/issues/1193): \[core] Designer doesn't start with run.sh
 *   ecmascript
     *   [#861](https://github.com/pmd/pmd/issues/861): \[ecmascript] InnaccurateNumericLiteral false positive with hex literals
+*   java
+    *   [#1074](https://github.com/pmd/pmd/issues/1074): \[java] MissingOverrideRule exception when analyzing PMD under Java 9
 *   java-bestpractices
     *   [#651](https://github.com/pmd/pmd/issues/651): \[java] SwitchStmtsShouldHaveDefault should be aware of enum types
     *   [#869](https://github.com/pmd/pmd/issues/869): \[java] GuardLogStatement false positive on return statements and Math.log

diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/util/ClasspathClassLoader.java b/pmd-core/src/main/java/net/sourceforge/pmd/util/ClasspathClassLoader.java
@@ -102,13 +102,30 @@ public String toString() {
                 .append(StringUtils.join(getURLs(), ":"))
                 .append("] parent: ").append(getParent()).append(']').toString();
     }
-
+
+    /**
+     * Tries to load the given class. Note: This classloader first tries to load the class
+     * itself and if that fails, delegates to the parent class loader.
+     * This is needed, if the project being analyzed by PMD uses the same dependencies as PMD itself
+     * (e.g. apache commons) but in a different version. Trying to resolve the class first
+     * within this classloader makes sure, to use the correct version for type resolution.
+     */
     @Override
     protected Class<?> loadClass(final String name, final boolean resolve) throws ClassNotFoundException {
         synchronized (getClassLoadingLock(name)) {
             // First, check if the class has already been loaded
             Class<?> c = findLoadedClass(name);
             if (c == null) {
+
+                // exception for org.w3c.dom.UserDataHandler, which is on the JDK classpath
+                // and on jaxen
+                // see https://github.com/pmd/pmd/issues/1074
+                // we can directly return here, since PMD needs to run with java 7+, which
+                // for sure has this interface on the JDK classpath
+                if ("org.w3c.dom.UserDataHandler".equals(name)) {
+                    return super.loadClass(name, resolve);
+                }
+
                 try {
                     // checking local
                     c = findClass(name);
@@ -118,7 +135,7 @@ protected Class<?> loadClass(final String name, final boolean resolve) throws Cl
                     c = super.loadClass(name, resolve);
                 }
             }
-    
+
             if (resolve) {
                 resolveClass(c);
             }