diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ConfigListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ConfigListener.java
index f68b165..9c951ae 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ConfigListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ConfigListener.java
@@ -21,14 +21,16 @@
 import org.onosproject.yangutils.datamodel.YangLeafList;
 import org.onosproject.yangutils.datamodel.YangList;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;
+
+import static org.onosproject.yangutils.parser.ParsableDataType.CONFIG_DATA;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -69,8 +71,7 @@
         boolean isConfig = false;
 
         // Check for stack to be non empty.
-        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
-                ParsableDataType.CONFIG_DATA, "", ListenerErrorLocation.ENTRY);
+        checkStackIsNotEmpty(listener, MISSING_HOLDER, CONFIG_DATA, "", ENTRY);
 
         if (ctx.TRUE_KEYWORD() != null) {
             isConfig = true;
@@ -97,10 +98,7 @@
             case CHOICE_DATA: // TODO
                 break;
             default:
-                throw new ParserException(ListenerErrorMessageConstruction
-                        .constructListenerErrorMessage(ListenerErrorType.INVALID_HOLDER,
-                                ParsableDataType.CONFIG_DATA,
-                                "", ListenerErrorLocation.ENTRY));
+                throw new ParserException(constructListenerErrorMessage(INVALID_HOLDER, CONFIG_DATA, "", ENTRY));
         }
     }
 }
\ No newline at end of file
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ContainerListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ContainerListener.java
index e330350..08be582f 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ContainerListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ContainerListener.java
@@ -15,20 +15,30 @@
  */
 
 package org.onosproject.yangutils.parser.impl.listeners;
+
 import org.onosproject.yangutils.datamodel.YangContainer;
+import org.onosproject.yangutils.datamodel.YangList;
+import org.onosproject.yangutils.datamodel.YangModule;
 import org.onosproject.yangutils.datamodel.YangNode;
 import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
 import org.onosproject.yangutils.parser.Parsable;
-
 import org.onosproject.yangutils.parser.ParsableDataType;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
 import org.onosproject.yangutils.parser.impl.YangUtilsParserManager;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;
+
+import static org.onosproject.yangutils.parser.ParsableDataType.CONTAINER_DATA;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.EXIT;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructExtendedListenerErrorMessage;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.UNHANDLED_PARSED_DATA;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_CARDINALITY;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_CURRENT_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -85,15 +95,11 @@
                                              GeneratedYangParser.ContainerStatementContext ctx) {
 
         // Check for stack to be non empty.
-        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
-                ParsableDataType.CONTAINER_DATA, String.valueOf(ctx.IDENTIFIER().getText()),
-                ListenerErrorLocation.ENTRY);
+        checkStackIsNotEmpty(listener, MISSING_HOLDER, CONTAINER_DATA, ctx.IDENTIFIER().getText(), ENTRY);
 
         boolean result = validateSubStatementsCardinality(ctx);
         if (!result) {
-            throw new ParserException(ListenerErrorMessageConstruction
-                    .constructListenerErrorMessage(ListenerErrorType.INVALID_CARDINALITY,
-                            yangConstruct, "", ListenerErrorLocation.ENTRY));
+            throw new ParserException(constructListenerErrorMessage(INVALID_CARDINALITY, yangConstruct, "", ENTRY));
         }
 
         YangContainer container = new YangContainer();
@@ -101,25 +107,19 @@
 
         Parsable curData = listener.getParsedDataStack().peek();
 
-        if (curData instanceof YangNode) {
+        if ((curData instanceof YangModule) || (curData instanceof YangContainer)
+                || (curData instanceof YangList)) {
             YangNode curNode = (YangNode) curData;
             try {
                 curNode.addChild(container);
             } catch (DataModelException e) {
-                throw new ParserException(ListenerErrorMessageConstruction
-                        .constructExtendedListenerErrorMessage(ListenerErrorType.UNHANDLED_PARSED_DATA,
-                                ParsableDataType.CONTAINER_DATA,
-                                String.valueOf(ctx.IDENTIFIER().getText()),
-                                ListenerErrorLocation.ENTRY,
-                                e.getMessage()));
+                throw new ParserException(constructExtendedListenerErrorMessage(UNHANDLED_PARSED_DATA,
+                                CONTAINER_DATA, ctx.IDENTIFIER().getText(), ENTRY, e.getMessage()));
             }
             listener.getParsedDataStack().push(container);
         } else {
-            throw new ParserException(ListenerErrorMessageConstruction
-                    .constructListenerErrorMessage(ListenerErrorType.INVALID_HOLDER,
-                            ParsableDataType.CONTAINER_DATA,
-                            String.valueOf(ctx.IDENTIFIER().getText()),
-                            ListenerErrorLocation.ENTRY));
+            throw new ParserException(constructListenerErrorMessage(INVALID_HOLDER, CONTAINER_DATA,
+                    ctx.IDENTIFIER().getText(), ENTRY));
         }
     }
 
@@ -134,18 +134,13 @@
                                             GeneratedYangParser.ContainerStatementContext ctx) {
 
         // Check for stack to be non empty.
-        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
-                ParsableDataType.CONTAINER_DATA, String.valueOf(ctx.IDENTIFIER().getText()),
-                ListenerErrorLocation.EXIT);
+        checkStackIsNotEmpty(listener, MISSING_HOLDER, CONTAINER_DATA, ctx.IDENTIFIER().getText(), EXIT);
 
         if (listener.getParsedDataStack().peek() instanceof YangContainer) {
             listener.getParsedDataStack().pop();
         } else {
-            throw new ParserException(ListenerErrorMessageConstruction
-                    .constructListenerErrorMessage(ListenerErrorType.INVALID_HOLDER,
-                            ParsableDataType.CONTAINER_DATA,
-                            String.valueOf(ctx.IDENTIFIER().getText()),
-                            ListenerErrorLocation.EXIT));
+            throw new ParserException(constructListenerErrorMessage(MISSING_CURRENT_HOLDER, CONTAINER_DATA,
+                            ctx.IDENTIFIER().getText(), EXIT));
         }
     }
 
@@ -155,7 +150,7 @@
      * @param ctx context object of the grammar rule.
      * @return true/false validation success or failure.
      */
-    public static boolean validateSubStatementsCardinality(GeneratedYangParser.ContainerStatementContext ctx) {
+    private static boolean validateSubStatementsCardinality(GeneratedYangParser.ContainerStatementContext ctx) {
 
         if ((!ctx.presenceStatement().isEmpty())
                 && (ctx.presenceStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/DescriptionListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/DescriptionListener.java
index a328cb7..1befa54 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/DescriptionListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/DescriptionListener.java
@@ -18,14 +18,16 @@
 
 import org.onosproject.yangutils.datamodel.YangDesc;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;
+
+import static org.onosproject.yangutils.parser.ParsableDataType.DESCRIPTION_DATA;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -61,20 +63,15 @@
                                              GeneratedYangParser.DescriptionStatementContext ctx) {
 
         // Check for stack to be non empty.
-        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
-                ParsableDataType.DESCRIPTION_DATA, String.valueOf(ctx.string().getText()),
-                ListenerErrorLocation.ENTRY);
+        checkStackIsNotEmpty(listener, MISSING_HOLDER, DESCRIPTION_DATA, ctx.string().getText(), ENTRY);
 
         Parsable tmpData = listener.getParsedDataStack().peek();
         if (tmpData instanceof YangDesc) {
             YangDesc description = (YangDesc) tmpData;
             description.setDescription(ctx.string().getText());
         } else {
-            throw new ParserException(ListenerErrorMessageConstruction
-                    .constructListenerErrorMessage(ListenerErrorType.INVALID_HOLDER,
-                            ParsableDataType.DESCRIPTION_DATA,
-                            String.valueOf(ctx.string().getText()),
-                            ListenerErrorLocation.ENTRY));
+            throw new ParserException(constructListenerErrorMessage(INVALID_HOLDER, DESCRIPTION_DATA,
+                    ctx.string().getText(), ENTRY));
         }
     }
 }
\ No newline at end of file
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/LeafListListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/LeafListListener.java
index 829dd10..1ada6dd 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/LeafListListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/LeafListListener.java
@@ -24,10 +24,16 @@
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
 import org.onosproject.yangutils.parser.impl.YangUtilsParserManager;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;
+
+import static org.onosproject.yangutils.parser.ParsableDataType.LEAF_LIST_DATA;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.EXIT;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_CARDINALITY;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_CURRENT_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -82,15 +88,11 @@
                                             GeneratedYangParser.LeafListStatementContext ctx) {
 
         // Check for stack to be non empty.
-        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
-                ParsableDataType.LEAF_LIST_DATA, String.valueOf(ctx.IDENTIFIER().getText()),
-                ListenerErrorLocation.ENTRY);
+        checkStackIsNotEmpty(listener, MISSING_HOLDER, LEAF_LIST_DATA, ctx.IDENTIFIER().getText(), ENTRY);
 
         boolean result = validateSubStatementsCardinality(ctx);
         if (!result) {
-            throw new ParserException(ListenerErrorMessageConstruction
-                    .constructListenerErrorMessage(ListenerErrorType.INVALID_CARDINALITY,
-                            yangConstruct, "", ListenerErrorLocation.ENTRY));
+            throw new ParserException(constructListenerErrorMessage(INVALID_CARDINALITY, yangConstruct, "", ENTRY));
         }
 
         YangLeafList leafList = new YangLeafList();
@@ -103,11 +105,8 @@
             leaves = (YangLeavesHolder) tmpData;
             leaves.addLeafList(leafList);
         } else {
-            throw new ParserException(ListenerErrorMessageConstruction
-                    .constructListenerErrorMessage(ListenerErrorType.INVALID_HOLDER,
-                            ParsableDataType.LEAF_LIST_DATA,
-                            String.valueOf(ctx.IDENTIFIER().getText()),
-                            ListenerErrorLocation.ENTRY));
+            throw new ParserException(constructListenerErrorMessage(INVALID_HOLDER, LEAF_LIST_DATA,
+                            ctx.IDENTIFIER().getText(), ENTRY));
         }
         listener.getParsedDataStack().push(leafList);
     }
@@ -123,18 +122,13 @@
                                            GeneratedYangParser.LeafListStatementContext ctx) {
 
         // Check for stack to be non empty.
-        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
-                ParsableDataType.LEAF_LIST_DATA, String.valueOf(ctx.IDENTIFIER().getText()),
-                ListenerErrorLocation.EXIT);
+        checkStackIsNotEmpty(listener, MISSING_HOLDER, LEAF_LIST_DATA, ctx.IDENTIFIER().getText(), EXIT);
 
         if (listener.getParsedDataStack().peek() instanceof YangLeafList) {
             listener.getParsedDataStack().pop();
         } else {
-            throw new ParserException(ListenerErrorMessageConstruction
-                    .constructListenerErrorMessage(ListenerErrorType.INVALID_HOLDER,
-                            ParsableDataType.LEAF_LIST_DATA,
-                            String.valueOf(ctx.IDENTIFIER().getText()),
-                            ListenerErrorLocation.EXIT));
+            throw new ParserException(constructListenerErrorMessage(MISSING_CURRENT_HOLDER, LEAF_LIST_DATA,
+                    ctx.IDENTIFIER().getText(), EXIT));
         }
     }
 
@@ -144,7 +138,7 @@
      * @param ctx context object of the grammar rule.
      * @return true/false validation success or failure.
      */
-    public static boolean validateSubStatementsCardinality(GeneratedYangParser
+    private static boolean validateSubStatementsCardinality(GeneratedYangParser
             .LeafListStatementContext ctx) {
 
         if (ctx.typeStatement().isEmpty()
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/LeafListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/LeafListener.java
index 2de3344..81e9e1c 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/LeafListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/LeafListener.java
@@ -28,10 +28,16 @@
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
 import org.onosproject.yangutils.datamodel.YangLeavesHolder;
 import org.onosproject.yangutils.parser.impl.YangUtilsParserManager;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;
+
+import static org.onosproject.yangutils.parser.ParsableDataType.LEAF_DATA;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.EXIT;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_CARDINALITY;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_CURRENT_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -85,15 +91,11 @@
                                         GeneratedYangParser.LeafStatementContext ctx) {
 
         // Check for stack to be non empty.
-        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
-                ParsableDataType.LEAF_DATA, String.valueOf(ctx.IDENTIFIER().getText()),
-                ListenerErrorLocation.ENTRY);
+        checkStackIsNotEmpty(listener, MISSING_HOLDER, LEAF_DATA, ctx.IDENTIFIER().getText(), ENTRY);
 
         boolean result = validateSubStatementsCardinality(ctx);
         if (!result) {
-            throw new ParserException(ListenerErrorMessageConstruction
-                    .constructListenerErrorMessage(ListenerErrorType.INVALID_CARDINALITY,
-                            yangConstruct, "", ListenerErrorLocation.ENTRY));
+            throw new ParserException(constructListenerErrorMessage(INVALID_CARDINALITY, yangConstruct, "", ENTRY));
         }
 
         YangLeaf leaf = new YangLeaf();
@@ -106,11 +108,8 @@
             leaves = (YangLeavesHolder) tmpData;
             leaves.addLeaf(leaf);
         } else {
-            throw new ParserException(ListenerErrorMessageConstruction
-                    .constructListenerErrorMessage(ListenerErrorType.INVALID_HOLDER,
-                            ParsableDataType.LEAF_DATA,
-                            String.valueOf(ctx.IDENTIFIER().getText()),
-                            ListenerErrorLocation.ENTRY));
+            throw new ParserException(constructListenerErrorMessage(INVALID_HOLDER, LEAF_DATA,
+                    ctx.IDENTIFIER().getText(), ENTRY));
         }
 
         listener.getParsedDataStack().push(leaf);
@@ -127,18 +126,13 @@
                                        GeneratedYangParser.LeafStatementContext ctx) {
 
         // Check for stack to be non empty.
-        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
-                ParsableDataType.LEAF_DATA, String.valueOf(ctx.IDENTIFIER().getText()),
-                ListenerErrorLocation.EXIT);
+        checkStackIsNotEmpty(listener, MISSING_HOLDER, LEAF_DATA, ctx.IDENTIFIER().getText(), EXIT);
 
         if (listener.getParsedDataStack().peek() instanceof YangLeaf) {
             listener.getParsedDataStack().pop();
         } else {
-            throw new ParserException(ListenerErrorMessageConstruction
-                    .constructListenerErrorMessage(ListenerErrorType.INVALID_HOLDER,
-                            ParsableDataType.LEAF_DATA,
-                            String.valueOf(ctx.IDENTIFIER().getText()),
-                            ListenerErrorLocation.EXIT));
+            throw new ParserException(constructListenerErrorMessage(MISSING_CURRENT_HOLDER, LEAF_DATA,
+                            ctx.IDENTIFIER().getText(), EXIT));
         }
     }
 
@@ -148,7 +142,7 @@
      * @param ctx context object of the grammar rule.
      * @return true/false validation success or failure.
      */
-    public static boolean validateSubStatementsCardinality(GeneratedYangParser
+    private static boolean validateSubStatementsCardinality(GeneratedYangParser
             .LeafStatementContext ctx) {
 
         if (ctx.typeStatement().isEmpty()
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/MandatoryListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/MandatoryListener.java
index e0a3e6c..2e118ce 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/MandatoryListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/MandatoryListener.java
@@ -18,14 +18,16 @@
 
 import org.onosproject.yangutils.datamodel.YangLeaf;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;
+
+import static org.onosproject.yangutils.parser.ParsableDataType.MANDATORY_DATA;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -67,8 +69,7 @@
                                           GeneratedYangParser.MandatoryStatementContext ctx) {
 
         // Check for stack to be non empty.
-        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
-                ParsableDataType.MANDATORY_DATA, "", ListenerErrorLocation.ENTRY);
+        checkStackIsNotEmpty(listener, MISSING_HOLDER, MANDATORY_DATA, "", ENTRY);
 
         Parsable tmpNode = listener.getParsedDataStack().peek();
         switch (tmpNode.getParsableDataType()) {
@@ -83,9 +84,7 @@
             case CHOICE_DATA: // TODO
                 break;
             default:
-                throw new ParserException(ListenerErrorMessageConstruction
-                        .constructListenerErrorMessage(ListenerErrorType.INVALID_HOLDER,
-                                ParsableDataType.MANDATORY_DATA, "", ListenerErrorLocation.ENTRY));
+                throw new ParserException(constructListenerErrorMessage(INVALID_HOLDER, MANDATORY_DATA, "", ENTRY));
         }
     }
 }
\ No newline at end of file
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/MaxElementsListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/MaxElementsListener.java
index 84eefea..bf59311 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/MaxElementsListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/MaxElementsListener.java
@@ -19,14 +19,16 @@
 import org.onosproject.yangutils.datamodel.YangLeafList;
 import org.onosproject.yangutils.datamodel.YangList;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;
+
+import static org.onosproject.yangutils.parser.ParsableDataType.MAX_ELEMENT_DATA;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -66,8 +68,7 @@
         int maxElementsValue;
 
         // Check for stack to be non empty.
-        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
-                ParsableDataType.MAX_ELEMENT_DATA, "", ListenerErrorLocation.ENTRY);
+        checkStackIsNotEmpty(listener, MISSING_HOLDER, MAX_ELEMENT_DATA, "", ENTRY);
 
         if (ctx.maxValueArgument().UNBOUNDED_KEYWORD() != null) {
             maxElementsValue = Integer.MAX_VALUE;
@@ -86,10 +87,7 @@
                 yangList.setMaxElelements(maxElementsValue);
                 break;
             default:
-                throw new ParserException(ListenerErrorMessageConstruction
-                        .constructListenerErrorMessage(ListenerErrorType.INVALID_HOLDER,
-                                ParsableDataType.MAX_ELEMENT_DATA,
-                                "", ListenerErrorLocation.ENTRY));
+                throw new ParserException(constructListenerErrorMessage(INVALID_HOLDER, MAX_ELEMENT_DATA, "", ENTRY));
         }
     }
 }
\ No newline at end of file
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/MinElementsListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/MinElementsListener.java
index 87a9cdb..8e1e2f7 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/MinElementsListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/MinElementsListener.java
@@ -19,14 +19,16 @@
 import org.onosproject.yangutils.datamodel.YangLeafList;
 import org.onosproject.yangutils.datamodel.YangList;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;
+
+import static org.onosproject.yangutils.parser.ParsableDataType.MIN_ELEMENT_DATA;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -66,9 +68,7 @@
                                                GeneratedYangParser.MinElementsStatementContext ctx) {
 
         // Check for stack to be non empty.
-        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
-                ParsableDataType.MIN_ELEMENT_DATA, String.valueOf(ctx.INTEGER().getText()),
-                ListenerErrorLocation.ENTRY);
+        checkStackIsNotEmpty(listener, MISSING_HOLDER, MIN_ELEMENT_DATA, ctx.INTEGER().getText(), ENTRY);
 
         Parsable tmpData = listener.getParsedDataStack().peek();
         switch (tmpData.getParsableDataType()) {
@@ -81,11 +81,8 @@
                 yangList.setMinElements(Integer.parseInt(ctx.INTEGER().getText()));
                 break;
             default:
-                throw new ParserException(ListenerErrorMessageConstruction
-                        .constructListenerErrorMessage(ListenerErrorType.INVALID_HOLDER,
-                                ParsableDataType.MIN_ELEMENT_DATA,
-                                String.valueOf(ctx.INTEGER().getText()),
-                                ListenerErrorLocation.ENTRY));
+                throw new ParserException(constructListenerErrorMessage(INVALID_HOLDER, MIN_ELEMENT_DATA,
+                        ctx.INTEGER().getText(), ENTRY));
         }
     }
 }
\ No newline at end of file
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/PresenceListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/PresenceListener.java
index b63f901..a771307 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/PresenceListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/PresenceListener.java
@@ -18,14 +18,17 @@
 
 import org.onosproject.yangutils.datamodel.YangContainer;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;
+
+import static org.onosproject.yangutils.parser.ParsableDataType.PRESENCE_DATA;
+import static org.onosproject.yangutils.parser.ParsableDataType.CONTAINER_DATA;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -61,20 +64,15 @@
                                              GeneratedYangParser.PresenceStatementContext ctx) {
 
         // Check for stack to be non empty.
-        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
-                ParsableDataType.PRESENCE_DATA, String.valueOf(ctx.string().getText()),
-                ListenerErrorLocation.ENTRY);
+        checkStackIsNotEmpty(listener, MISSING_HOLDER, PRESENCE_DATA, ctx.string().getText(), ENTRY);
 
         Parsable tmpData = listener.getParsedDataStack().peek();
-        if (tmpData.getParsableDataType() == ParsableDataType.CONTAINER_DATA) {
+        if (tmpData.getParsableDataType() == CONTAINER_DATA) {
             YangContainer container = (YangContainer) tmpData;
             container.setPresence(ctx.string().getText());
         } else {
-            throw new ParserException(ListenerErrorMessageConstruction
-                    .constructListenerErrorMessage(ListenerErrorType.INVALID_HOLDER,
-                            ParsableDataType.PRESENCE_DATA,
-                            String.valueOf(ctx.string().getText()),
-                            ListenerErrorLocation.ENTRY));
+            throw new ParserException(constructListenerErrorMessage(INVALID_HOLDER, PRESENCE_DATA,
+                    ctx.string().getText(), ENTRY));
         }
     }
 }
\ No newline at end of file
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ReferenceListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ReferenceListener.java
index 2c6e0d0..6e83e86 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ReferenceListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ReferenceListener.java
@@ -18,14 +18,16 @@
 
 import org.onosproject.yangutils.datamodel.YangReference;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;
+
+import static org.onosproject.yangutils.parser.ParsableDataType.REFERENCE_DATA;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -61,20 +63,15 @@
                                              GeneratedYangParser.ReferenceStatementContext ctx) {
 
         // Check for stack to be non empty.
-        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
-                ParsableDataType.REFERENCE_DATA, String.valueOf(ctx.string().getText()),
-                ListenerErrorLocation.ENTRY);
+        checkStackIsNotEmpty(listener, MISSING_HOLDER, REFERENCE_DATA, ctx.string().getText(), ENTRY);
 
         Parsable tmpData = listener.getParsedDataStack().peek();
         if (tmpData instanceof YangReference) {
             YangReference reference = (YangReference) tmpData;
             reference.setReference(ctx.string().getText());
         } else {
-            throw new ParserException(ListenerErrorMessageConstruction
-                    .constructListenerErrorMessage(ListenerErrorType.INVALID_HOLDER,
-                            ParsableDataType.REFERENCE_DATA,
-                            String.valueOf(ctx.string().getText()),
-                            ListenerErrorLocation.ENTRY));
+            throw new ParserException(constructListenerErrorMessage(INVALID_HOLDER, REFERENCE_DATA,
+                            ctx.string().getText(), ENTRY));
         }
     }
 }
\ No newline at end of file
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/StatusListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/StatusListener.java
index c52f3e6..82cdabd 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/StatusListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/StatusListener.java
@@ -19,14 +19,16 @@
 import org.onosproject.yangutils.datamodel.YangStatus;
 import org.onosproject.yangutils.datamodel.YangStatusType;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;
+
+import static org.onosproject.yangutils.parser.ParsableDataType.STATUS_DATA;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -68,15 +70,14 @@
         YangStatusType status;
 
         // Check for stack to be non empty.
-        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
-                ParsableDataType.STATUS_DATA, "", ListenerErrorLocation.ENTRY);
+        checkStackIsNotEmpty(listener, MISSING_HOLDER, STATUS_DATA, "", ENTRY);
 
         if (ctx.CURRENT_KEYWORD() != null) {
-            status = YangStatusType.CURRENT.CURRENT;
+            status = YangStatusType.CURRENT;
         } else if (ctx.DEPRECATED_KEYWORD() != null) {
             status = YangStatusType.DEPRECATED;
         } else {
-            status = YangStatusType.OBSOLETE.OBSOLETE;
+            status = YangStatusType.OBSOLETE;
         }
 
         Parsable tmpData = listener.getParsedDataStack().peek();
@@ -84,9 +85,7 @@
             YangStatus yangStatus = (YangStatus) tmpData;
             yangStatus.setStatus(status);
         } else {
-            throw new ParserException(ListenerErrorMessageConstruction
-                    .constructListenerErrorMessage(ListenerErrorType.INVALID_HOLDER,
-                            ParsableDataType.STATUS_DATA, "", ListenerErrorLocation.ENTRY));
+            throw new ParserException(constructListenerErrorMessage(INVALID_HOLDER, STATUS_DATA, "", ENTRY));
         }
     }
 }
\ No newline at end of file
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/TypeListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/TypeListener.java
index fffa86a..e5ebf36 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/TypeListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/TypeListener.java
@@ -21,14 +21,17 @@
 import org.onosproject.yangutils.datamodel.YangLeafList;
 import org.onosproject.yangutils.datamodel.YangType;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;
+
+import static org.onosproject.yangutils.parser.ParsableDataType.TYPE_DATA;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
+
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -68,9 +71,7 @@
                                         GeneratedYangParser.TypeStatementContext ctx) {
 
         // Check for stack to be non empty.
-        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
-                ParsableDataType.TYPE_DATA, String.valueOf(ctx.string().getText()),
-                ListenerErrorLocation.ENTRY);
+        checkStackIsNotEmpty(listener, MISSING_HOLDER, TYPE_DATA, ctx.string().getText(), ENTRY);
 
         YangType type = new YangType();
         YangDataTypes yangDataTypes = YangDataTypes.getType(ctx.string().getText());
@@ -90,11 +91,8 @@
             case TYPEDEF_DATA: //TODO
                 break;
             default:
-                throw new ParserException(ListenerErrorMessageConstruction
-                        .constructListenerErrorMessage(ListenerErrorType.INVALID_HOLDER,
-                                ParsableDataType.TYPE_DATA,
-                                String.valueOf(ctx.string().getText()),
-                                ListenerErrorLocation.ENTRY));
+                throw new ParserException(constructListenerErrorMessage(INVALID_HOLDER, TYPE_DATA,
+                        ctx.string().getText(), ENTRY));
         }
     }
 }
\ No newline at end of file
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/UnitsListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/UnitsListener.java
index e846b42..6a83aaa 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/UnitsListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/UnitsListener.java
@@ -19,14 +19,16 @@
 import org.onosproject.yangutils.datamodel.YangLeaf;
 import org.onosproject.yangutils.datamodel.YangLeafList;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;
+
+import static org.onosproject.yangutils.parser.ParsableDataType.UNITS_DATA;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -62,9 +64,7 @@
                                            GeneratedYangParser.UnitsStatementContext ctx) {
 
         // Check for stack to be non empty.
-        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
-                ParsableDataType.UNITS_DATA, String.valueOf(ctx.string().getText()),
-                ListenerErrorLocation.ENTRY);
+        checkStackIsNotEmpty(listener, MISSING_HOLDER, UNITS_DATA, ctx.string().getText(), ENTRY);
 
         Parsable tmpData = listener.getParsedDataStack().peek();
         switch (tmpData.getParsableDataType()) {
@@ -80,11 +80,8 @@
                 // TODO
                 break;
             default:
-                throw new ParserException(ListenerErrorMessageConstruction
-                        .constructListenerErrorMessage(ListenerErrorType.INVALID_HOLDER,
-                                ParsableDataType.UNITS_DATA,
-                                String.valueOf(ctx.string().getText()),
-                                ListenerErrorLocation.ENTRY));
+                throw new ParserException(constructListenerErrorMessage(INVALID_HOLDER, UNITS_DATA,
+                                ctx.string().getText(), ENTRY));
         }
     }
 }
\ No newline at end of file