ArrayStackOfStrings.java

ArrayStackOfStrings.java

import java.util.Iterator;

public class ArrayStackOfStrings implements Iterable

{

    private String[] a; 

    private int N;      

    public ArrayStackOfStrings(int max)

   { 

           a = new String[max];   

    }

    public boolean isEmpty()           

   { 

         return (N == 0);          

   }

    public void push(String item)      

    { 

         a[N++] = item;          

     }

    public String pop()               

    {   

        return a[--N];        

     }

    public Iterator iterator()

 {  

       return new ArrayIterator();

  }

             public class ArrayIterator implements Iterator

              {

        private int i = N-1;

                    public boolean hasNext()

                     {

                              return i >= 0;

                      }

        public String next()   

        {

                 return a[i--];

         }

        public void remove()     

       { throw new UnsupportedOperationException(); }

    }

                public static void main(String[] args)

                    {

        int max = Integer.parseInt(args[0]);

        ArrayStackOfStrings stack = new ArrayStackOfStrings(max);

        while (!StdIn.isEmpty())

         {

            String item = StdIn.readString();

            if (!item.equals("-"))

            stack.push(item);

            else if (stack.isEmpty()) 

            StdOut.println("BAD INPUT");

            else                      

            StdOut.print(stack.pop() + " ");

        }

        StdOut.println();

                    StdOut.print("Left on stack: ");

        for (String s : stack)

        {

            StdOut.print(s + " ");

        }

        StdOut.println();

    }

}