Stk.java

public class Stk implements IStk {

    public final int MAXSIZE =100;
    private int top;
    private int bot;
    private int front;
    private int rear;
    private int maxStk;
    private char items [];

    public Stk ()
    {
        this.front=0;
        this.rear=0;
        this.maxStk=0;
        this.items = new char [MAXSIZE];
    }

    public Stk(int max)
    {
        this.maxStk = max+1;
        this.front = maxStk - 1;
        this.rear = maxStk - 1;
        this.items = new char [max];
    }

    public boolean isFull ()
    {
        // WRAP AROUND
        return ( (this.top + 1) % this.maxStk == this.bot );
    }

    public boolean isEmpty ()
    {
        return ( this.bot == this.top );
    }

    public void push (char item)
    {
        if (!isFull())
        {  this.top = (this.top+1) % this.maxStk;
            this.items[top] = item;
        }
        else
            System.out.println ("Tried to insert into full stack.");
    }

    public char pop ()
    {
        char item;
        if (!isEmpty())
        {
            item = this.items[top];
            this.top = (this.top-1) % this.maxStk;
            return item;
        }
        else {
            System.out.println ("Tried to remove from empty stack.");
            return 0;
        }

    }

}