JStack Implementation in Array

JStackArray.java

package com.codehackersblog.stack;

import java.util.Scanner;

/**
*
* @author Psycho_Coder
*/
public class JStackArray implements StackInterface {

   private final static int DEFAULT_SIZE = 5;
   private final int[] stack;
   private int top;
   private final int SIZE;
   private static JStack st;
   private static int NO_OF_ELEMENTS;
   public JStackArray() {
       SIZE = DEFAULT_SIZE;
       stack = new int;
       top = -1;
       NO_OF_ELEMENTS = 0;
   }

   public JStackArray(int SIZE) {
       this.SIZE = SIZE;
       stack = new int;
       top=-1;
       NO_OF_ELEMENTS = 0;
   }

   @Override
   public void push(int item) {
       if (!isFull()) {
           stack[++top] = item;
           ++NO_OF_ELEMENTS;
       } else {
           out("Stack Overflow! Please remove some elements from stack.");
       }
   }

   @Override
   public int pop() {
       int k = -1;
       if (!isEmpty()) {
           k = stack[top];
           --top;
           --NO_OF_ELEMENTS;
       }
       return k;
   }

   @Override
   public boolean isEmpty() {
       return top == -1;
   }

   @Override
   public boolean isFull() {
       return top == SIZE;
   }

   @Override
   public int size() {
       return stack.length;
   }

   @Override
   public int peek() {
       return stack[top];
   }

   private void display() {
       out("The elements in the stack are : ");
       for (int i = NO_OF_ELEMENTS-1; i >= 0; i--) {
           System.out.print(stack[i] + " ");
       }
       out("\n");
   }

   public static void out(String data) {
       System.out.println(data);
   }

   public static void main(String[] args) {
       int item, choice;
       boolean conti = true;
       Scanner sc = new Scanner(System.in);
       if (args.length == 1) {
           st = new JStackArray(Integer.parseInt(args[0]));
       } else {
           st = new JStackArray();
       }

       while (conti) {
           out("\nMenu");
           out("1. Push");
           out("2. Pop");
           out("3. Peek");
           out("4. Size");
           out("5. Display");
           out("6. Exit");
           out("Enter your choice : ");
           choice = sc.nextInt();

           switch (choice) {
               case 1:
                   out("Enter the item :");
                   item = sc.nextInt();
                   st.push(item);
                   break;
               case 2:
                   int k = st.pop();
                   out(k == -1 ? "Stack Underflow! Please insert some elements into stack." : ("Element Poped" + k));
                   break;
               case 3:
                   out("Top element :" + st.peek());
                   break;
               case 4:
                   out("Size of the Stack : " + st.size());
                   break;
               case 5:
                   st.display();
                   break;
               case 6:
                   conti = false;
                   break;
               default:
                   out("Wrong Choice. Please try agian!");
           }
       }
   }
}