diff --git a/src/main/java/org/onosproject/yangutils/parser/impl/listeners/LeafListener.java b/src/main/java/org/onosproject/yangutils/parser/impl/listeners/LeafListener.java
index 81e9e1c..226f621 100644
--- a/src/main/java/org/onosproject/yangutils/parser/impl/listeners/LeafListener.java
+++ b/src/main/java/org/onosproject/yangutils/parser/impl/listeners/LeafListener.java
@@ -21,23 +21,29 @@
 package org.onosproject.yangutils.parser.impl.listeners;
 
 import org.onosproject.yangutils.datamodel.YangLeaf;
+import org.onosproject.yangutils.datamodel.YangLeavesHolder;
 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.datamodel.YangLeavesHolder;
-import org.onosproject.yangutils.parser.impl.YangUtilsParserManager;
-
-import static org.onosproject.yangutils.parser.ParsableDataType.LEAF_DATA;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerCollisionDetector.detectCollidingChildUtil;
 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.ListenerErrorType.MISSING_HOLDER;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.validateCardinality;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.validateCardinalityEqualsOne;
+import static org.onosproject.yangutils.utils.YangConstructType.CONFIG_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.DESCRIPTION_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.LEAF_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.MANDATORY_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.REFERENCE_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.STATUS_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.TYPE_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.UNITS_DATA;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -66,13 +72,11 @@
  */
 
 /**
- * Implements listener based call back function corresponding to the "leaf"
- * rule defined in ANTLR grammar file for corresponding ABNF rule in RFC 6020.
+ * Implements listener based call back function corresponding to the "leaf" rule
+ * defined in ANTLR grammar file for corresponding ABNF rule in RFC 6020.
  */
 public final class LeafListener {
 
-    private static ParsableDataType yangConstruct;
-
     /**
      * Creates a new leaf listener.
      */
@@ -80,23 +84,26 @@
     }
 
     /**
-     * It is called when parser receives an input matching the grammar
-     * rule (leaf), performs validation and updates the data model
-     * tree.
+     * It is called when parser receives an input matching the grammar rule
+     * (leaf), performs validation and updates the data model tree.
      *
-     * @param listener listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processLeafEntry(TreeWalkListener listener,
-                                        GeneratedYangParser.LeafStatementContext ctx) {
+            GeneratedYangParser.LeafStatementContext ctx) {
 
         // Check for stack to be non empty.
         checkStackIsNotEmpty(listener, MISSING_HOLDER, LEAF_DATA, ctx.IDENTIFIER().getText(), ENTRY);
 
-        boolean result = validateSubStatementsCardinality(ctx);
-        if (!result) {
-            throw new ParserException(constructListenerErrorMessage(INVALID_CARDINALITY, yangConstruct, "", ENTRY));
-        }
+        // Validate sub statement cardinality.
+        validateSubStatementsCardinality(ctx);
+
+        // Check for identifier collision
+        int line = ctx.IDENTIFIER().getSymbol().getLine();
+        int charPositionInLine = ctx.IDENTIFIER().getSymbol().getCharPositionInLine();
+        String identifierName = ctx.IDENTIFIER().getText();
+        detectCollidingChildUtil(listener, line, charPositionInLine, identifierName, LEAF_DATA);
 
         YangLeaf leaf = new YangLeaf();
         leaf.setLeafName(ctx.IDENTIFIER().getText());
@@ -123,7 +130,7 @@
      * @param ctx context object of the grammar rule.
      */
     public static void processLeafExit(TreeWalkListener listener,
-                                       GeneratedYangParser.LeafStatementContext ctx) {
+            GeneratedYangParser.LeafStatementContext ctx) {
 
         // Check for stack to be non empty.
         checkStackIsNotEmpty(listener, MISSING_HOLDER, LEAF_DATA, ctx.IDENTIFIER().getText(), EXIT);
@@ -132,7 +139,7 @@
             listener.getParsedDataStack().pop();
         } else {
             throw new ParserException(constructListenerErrorMessage(MISSING_CURRENT_HOLDER, LEAF_DATA,
-                            ctx.IDENTIFIER().getText(), EXIT));
+                    ctx.IDENTIFIER().getText(), EXIT));
         }
     }
 
@@ -140,53 +147,16 @@
      * Validates the cardinality of leaf sub-statements as per grammar.
      *
      * @param ctx context object of the grammar rule.
-     * @return true/false validation success or failure.
      */
-    private static boolean validateSubStatementsCardinality(GeneratedYangParser
-            .LeafStatementContext ctx) {
+    private static void validateSubStatementsCardinality(GeneratedYangParser.LeafStatementContext ctx) {
 
-        if (ctx.typeStatement().isEmpty()
-                || (ctx.typeStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.TYPE_DATA;
-            return false;
-        }
-
-        if ((!ctx.unitsStatement().isEmpty())
-                && (ctx.unitsStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.UNITS_DATA;
-            return false;
-        }
-
-        if ((!ctx.configStatement().isEmpty())
-                && (ctx.configStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.CONFIG_DATA;
-            return false;
-        }
-
-        if ((!ctx.mandatoryStatement().isEmpty())
-                && (ctx.mandatoryStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.MANDATORY_DATA;
-            return false;
-        }
-
-        if ((!ctx.descriptionStatement().isEmpty())
-                && (ctx.descriptionStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.DESCRIPTION_DATA;
-            return false;
-        }
-
-        if ((!ctx.referenceStatement().isEmpty())
-                && (ctx.referenceStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.REFERENCE_DATA;
-            return false;
-        }
-
-        if ((!ctx.statusStatement().isEmpty())
-                && (ctx.statusStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.STATUS_DATA;
-            return false;
-        }
-
-        return true;
+        validateCardinalityEqualsOne(ctx.typeStatement(), TYPE_DATA, LEAF_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.unitsStatement(), UNITS_DATA, LEAF_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.configStatement(), CONFIG_DATA, LEAF_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.mandatoryStatement(), MANDATORY_DATA, LEAF_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.descriptionStatement(), DESCRIPTION_DATA, LEAF_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.referenceStatement(), REFERENCE_DATA, LEAF_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.statusStatement(), STATUS_DATA, LEAF_DATA, ctx.IDENTIFIER().getText());
+        //TODO when.
     }
-}
\ No newline at end of file
+}