Fixed casting exception, refactored code

src/com/magento/idea/magento2plugin/indexes/XmlIndex.java

@@ -1,74 +1,80 @@
-/**
+/*
  * Copyright © Magento, Inc. All rights reserved.
  * See COPYING.txt for license details.
  */
+
 package com.magento.idea.magento2plugin.indexes;
 
-import com.intellij.openapi.project.Project;
 import com.intellij.openapi.vfs.VirtualFile;
+import com.intellij.psi.PsiFile;
 import com.intellij.psi.PsiManager;
 import com.intellij.psi.search.GlobalSearchScope;
 import com.intellij.psi.util.PsiTreeUtil;
-import com.intellij.psi.xml.*;
+import com.intellij.psi.xml.XmlAttribute;
+import com.intellij.psi.xml.XmlFile;
+import com.intellij.psi.xml.XmlTag;
+import com.intellij.psi.xml.XmlTagValue;
 import com.intellij.util.indexing.FileBasedIndex;
 import com.jetbrains.php.lang.psi.elements.PhpClass;
 import com.magento.idea.magento2plugin.stubs.indexes.xml.PhpClassNameIndex;
-
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 
-public class XmlIndex {
-
-    private static XmlIndex INSTANCE;
-
-    private Project project;
+public final class XmlIndex {
 
     private XmlIndex() {
     }
 
-    public static XmlIndex getInstance(final Project project) {
-        if (null == INSTANCE) {
-            INSTANCE = new XmlIndex();
-        }
-        INSTANCE.project = project;
-        return INSTANCE;
-    }
-
-    public static List<XmlTag> getPhpClassDeclarations(PhpClass phpClass) {
-
-        List<XmlTag> result = new ArrayList<>();
-
-        String fqn = phpClass.getPresentableFQN();
-
-        PsiManager psiManager = PsiManager.getInstance(phpClass.getProject());
-
-        Collection<VirtualFile> vfs = FileBasedIndex.getInstance()
-            .getContainingFiles(PhpClassNameIndex.KEY, fqn, GlobalSearchScope.allScope(phpClass.getProject()));
-
-        for (VirtualFile vf : vfs) {
-            XmlFile xmlFile = (XmlFile)psiManager.findFile(vf);
-            if (xmlFile == null) {
+    /**
+     * Get PHP class declarations in the *.xml files.
+     *
+     * @param phpClass PhpClass
+     *
+     * @return List[XmlTag]
+     */
+    public static List<XmlTag> getPhpClassDeclarations(final PhpClass phpClass) {
+
+        final List<XmlTag> result = new ArrayList<>();
+        final String fqn = phpClass.getPresentableFQN();
+        final PsiManager psiManager = PsiManager.getInstance(phpClass.getProject());
+        final Collection<VirtualFile> vfs = FileBasedIndex.getInstance()
+                .getContainingFiles(
+                        PhpClassNameIndex.KEY,
+                        fqn,
+                        GlobalSearchScope.allScope(phpClass.getProject())
+                );
+
+        for (final VirtualFile vf : vfs) {
+            final PsiFile psiFile = psiManager.findFile(vf);
+
+            if (!(psiFile instanceof XmlFile)) {
                 continue;
             }
+            final XmlFile xmlFile = (XmlFile) psiFile;
+            final XmlTag[] xmlTags = PsiTreeUtil.getChildrenOfType(
+                    xmlFile.getFirstChild(),
+                    XmlTag.class
+            );
 
-            XmlTag xmlTags[] = PsiTreeUtil.getChildrenOfType(xmlFile.getFirstChild(), XmlTag.class);
             if (xmlTags == null) {
                 continue;
             }
-
-            for (XmlTag xmlTag: xmlTags) {
+            for (final XmlTag xmlTag: xmlTags) {
                 fillList(xmlTag, fqn, result);
             }
         }
 
         return result;
-
     }
 
-    private static void fillList(XmlTag parentTag, String fqn, List<XmlTag> list) {
-        for (XmlTag childTag: parentTag.getSubTags()) {
-            for (XmlAttribute xmlAttribute: childTag.getAttributes()) {
+    private static void fillList(
+            final XmlTag parentTag,
+            final String fqn,
+            final List<XmlTag> list
+    ) {
+        for (final XmlTag childTag: parentTag.getSubTags()) {
+            for (final XmlAttribute xmlAttribute: childTag.getAttributes()) {
                 String xmlAttributeValue = xmlAttribute.getValue();
                 if (xmlAttributeValue != null) {
                     xmlAttributeValue = xmlAttributeValue.startsWith("\\")
@@ -78,14 +84,13 @@ private static void fillList(XmlTag parentTag, String fqn, List<XmlTag> list) {
                     }
                 }
             }
-            XmlTagValue childTagValue = childTag.getValue();
+            final XmlTagValue childTagValue = childTag.getValue();
             String tagValue = childTagValue.getTrimmedText();
             tagValue = tagValue.startsWith("\\") ? tagValue.substring(1) : tagValue;
+
             if (!tagValue.isEmpty() && tagValue.startsWith(fqn)) {
                 list.add(childTag);
             }
-
-
             fillList(childTag, fqn, list);
         }
     }