diff --git a/QueueLink.java b/QueueLink.java
index 9d8f774..eaf4594 100644
--- a/QueueLink.java
+++ b/QueueLink.java
@@ -18,7 +18,7 @@ public QNode(int key) {
 //last node of LL
 class Queue
 {
-    QNode front, rear;
+    QNode front = null, rear = null;
       
     public Queue() {
         this.front = this.rear = null;
@@ -78,4 +78,4 @@ public static void main(String[] args)
          
         System.out.println("Dequeued item is "+ q.dequeue().key);
     }
-}
\ No newline at end of file
+}
diff --git a/README.md b/README.md
index 6192cf8..c96963a 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,2 @@
 # Data-Structures
-This repository contains implementation of data structures in java.
+This repository contains implementation of data structures programs in java.
diff --git a/StackDemo.java b/StackDemo.java
index c9d9ca7..c160372 100644
--- a/StackDemo.java
+++ b/StackDemo.java
@@ -1,5 +1,5 @@
     public class StackDemo {  
-     private static final int capacity = 3;  
+     private static final int capacity = 7;  
      int arr[] = new int[capacity];  
      int top = -1;  
       
diff --git a/StackLinkedlist.java b/StackLinkedlist.java
index 2d7fe69..41eceb8 100644
--- a/StackLinkedlist.java
+++ b/StackLinkedlist.java
@@ -47,7 +47,7 @@ public int getData()
 /*  Class linkedStack  */
 class linkedStack
 {
-    protected Node top ;
+    protected Node top = null ;
     protected int size ;
  
     /*  Constructor  */
@@ -182,4 +182,4 @@ public static void main(String[] args)
  
         } while (ch == 'Y'|| ch == 'y');                 
     }
-}
\ No newline at end of file
+}