[java] Fix grammar for <> in Java 1.8

- Fixes #888
 - Allow the contents of an anonymous class to use diamong notation, but
the anonymous class itself can't use it

pmd-java/etc/grammar/Java.jjt

@@ -1,4 +1,7 @@
 /**
+ * Fixes #888 [java] ParseException occurs with valid '<>' in Java 1.8 mode
+ * Juan Martin Sotuyo Dodero 01/2018
+ *====================================================================
  * Fixes #793 [java] Parser error with private method in nested classes in interfaces
  * Andreas Dangel 12/2017
  *====================================================================
@@ -333,9 +336,9 @@ public class JavaParser {
   private void checkForBadAnonymousDiamondUsage() {
     if (jdkVersion < 9) {
       ASTAllocationExpression node = (ASTAllocationExpression)jjtree.peekNode();
-      ASTTypeArguments types = node.getFirstDescendantOfType(ASTTypeArguments.class);
+      ASTTypeArguments types = node.getFirstChildOfType(ASTClassOrInterfaceType.class).getFirstChildOfType(ASTTypeArguments.class);
       if (node.isAnonymousClass() && types != null && types.isDiamond()) {
-          throwParseException("Cannot use '<>' with anonymous inner classes when running in JDK inferior to 9 mode!");
+        throwParseException("Cannot use '<>' with anonymous inner classes when running in JDK inferior to 9 mode!");
       }
     }
   }
@@ -2026,8 +2029,8 @@ void AllocationExpression():
             { inInterface = inInterfaceOld; } // always restore the flag after leaving the node
         ]
      )
+    { checkForBadAnonymousDiamondUsage(); }
   )
-  { checkForBadAnonymousDiamondUsage(); }
 }
 
 /*

pmd-java/src/test/java/net/sourceforge/pmd/lang/java/ast/ParserCornersTest.java

@@ -35,6 +35,33 @@ public class ParserCornersTest {
                 + "                TestInnerClassCallsOuterParent.super.toString();\n" + "            }\n"
                 + "        };\n" + "    }\n" + "}\n");
     }
+    
+    /**
+     * #888 PMD 6.0.0 can't parse valid <> under 1.8.
+     */
+    @Test
+    public void testDiamondUsageJava8() {
+        parseJava18("public class PMDExceptionTest {\n" + 
+                "  private Component makeUI() {\n" + 
+                "    String[] model = {\"123456\", \"7890\"};\n" + 
+                "    JComboBox<String> comboBox = new JComboBox<>(model);\n" + 
+                "    comboBox.setEditable(true);\n" + 
+                "    comboBox.setEditor(new BasicComboBoxEditor() {\n" + 
+                "      private Component editorComponent;\n" + 
+                "      @Override public Component getEditorComponent() {\n" + 
+                "        if (editorComponent == null) {\n" + 
+                "          JTextField tc = (JTextField) super.getEditorComponent();\n" + 
+                "          editorComponent = new JLayer<>(tc, new ValidationLayerUI<>());\n" + 
+                "        }\n" + 
+                "        return editorComponent;\n" + 
+                "      }\n" + 
+                "    });\n" + 
+                "    JPanel p = new JPanel();\n" + 
+                "    p.add(comboBox);\n" + 
+                "    return p;\n" + 
+                "  }\n" + 
+                "}");
+    }
 
     @Test
     public final void testGetFirstASTNameImageNull() {