Merge pull request #614 from fw8899/master

fix https://github.com/alibaba/p3c/issues/209

p3c-pmd/src/main/java/com/alibaba/p3c/pmd/lang/java/rule/oop/WrapperTypeEqualityRule.java

@@ -45,8 +45,14 @@ public class WrapperTypeEqualityRule extends AbstractAliRule {
         // possible elements around "==" are PrimaryExpression or UnaryExpression(e.g. a == -2)
         List<ASTPrimaryExpression> expressions = node.findChildrenOfType(ASTPrimaryExpression.class);
         if (expressions.size() == NumberConstants.INTEGER_SIZE_OR_LENGTH_2) {
-            if (NodeUtils.isWrapperType(expressions.get(0)) &&
-                    NodeUtils.isWrapperType(expressions.get(1))) {
+            // PMD can not resolve array length type, but only the
+            ASTPrimaryExpression left = expressions.get(0);
+            ASTPrimaryExpression right = expressions.get(1);
+
+            boolean bothArrayLength = isArrayLength(left) && isArrayLength(right);
+            boolean bothWrapperType = NodeUtils.isWrapperType(left) && NodeUtils.isWrapperType(right);
+
+            if (!bothArrayLength && bothWrapperType) {
                 addViolationWithMessage(data, node, "java.oop.WrapperTypeEqualityRule.violation.msg");
             }
         }
@@ -54,4 +60,9 @@ public class WrapperTypeEqualityRule extends AbstractAliRule {
         return super.visit(node, data);
     }
 
+    private boolean isArrayLength(ASTPrimaryExpression expression) {
+        // assume expression like "x.length" is the length of array, field with name "length" may result in misrecognition
+        return "length".equals(expression.jjtGetLastToken().getImage())
+            && ".".equals(expression.jjtGetFirstToken().getNext().getImage());
+    }
 }

p3c-pmd/src/test/resources/com/alibaba/p3c/pmd/lang/java/rule/oop/xml/WrapperTypeEqualityRule.xml

@@ -150,4 +150,28 @@
         <expected-problems>0</expected-problems>
         <code-ref id="wrong-result-fix" />
     </test-code>
+
+    <!-- ====================================================================== -->
+
+    <code-fragment id="array-length-equals">
+        <![CDATA[
+    public class Test {
+        public void foo(){
+            Integer[] a;
+            Integer[] b;
+            if (a.length == b.length) {
+                return;
+            };
+        }
+    }
+        ]]>
+    </code-fragment>
+    <test-code>
+        <description>array length equals</description>
+        <expected-problems>0</expected-problems>
+        <code-ref id="array-length-equals"/>
+    </test-code>
+
+    <!-- ====================================================================== -->
+
 </test-data>