public class StackTest
{
   public static void main(String[] args)
	{
	   Stack stack = new Stack(10);
		
		// Java automatically boxes the character or double into the wrapper
		stack.push('a');
		stack.push('b');
		stack.push(123.45);
		stack.push(456.78);
		
		// polymorphic call to wrapper toString Method
		System.out.println(stack.pop());  
		System.out.println(stack.pop());
		System.out.println(stack.pop());
		
		// Must cast to char, Java automatically unboxes the wrapped object
		char c = (Character)stack.pop();
		System.out.println(c);
	}

   static class Stack
	{
		int top;
		Object[] data;
		
		public Stack(int size)
		{
			data = new Object[size];
			top = -1;
		}
		
		public void push(Object o)
		{
			data[++top] = o;
		}
		
	   public Object pop()
		{
			return data[top--];
		}
	}
}