TestStack.java

/**
 * C07 L11
 * 
 * This class defines an integer stack that can hold 10 values.
 */
class Stack {
    private int stck[] = new int[10];
    private int tos;

    Stack() {
        tos = -1;
    }

    void push(int item) {
        if (tos == 9) {
            System.out.println("Stack is full.");
        } else {
            stck[++tos] = item;
        }
    }

    int pop() {
        if (tos < 0) {
            System.out.println("Stack underflow.");

            return 0;
        } else {
            return stck[tos--];
        }
    }
}

class TestStack {

    public static void main(String[] args) {
        Stack mystack1 = new Stack();
        Stack mystack2 = new Stack();

        for (int i = 0; i < 10; i++)
            mystack1.push(i);
        for (int i = 10; i < 20; i++)
            mystack2.push(i);

        System.out.println("Stack in mystack1:");
        for (int i = 0; i < 10; i++)
            System.out.println(mystack1.pop());

        System.out.println("Stack in mystack2:");
        for (int i = 0; i < 10; i++)
            System.out.println(mystack2.pop());

        // mystack1.tos = -2;
        // mystack1.stck[3] = 200;
    }
}