Stack.java

package lecture9a13;

public class Stack {
	protected int[] data;
	protected int tos;
   
	public Stack() {
		this.data = new int[5];
		this.tos = -1;
	}

	public Stack(int cap) {
		this.data = new int[cap];
		this.tos = -1;
	}

	public int size() {
		return this.tos + 1;
	}

	public boolean isEmpty() {
		return this.size() == 0;
	}

	public boolean isFull() {
		return size() == this.data.length;
	}

	public void push(int item) throws Exception {
		if (this.size() == this.data.length)
			throw new Exception("Stack is Full");
		
		this.tos++;
		this.data[this.tos] = item;
		
	}

	public int pop() throws Exception {
		if(this.size()==0)
			throw new Exception("Stack is Empty");
		int rv = this.data[this.tos];
		this.tos--;
		return rv;
	}

	public int peek() throws Exception {
		if(this.size()==0) {
			throw new Exception("Stack is Empty");
		}
		return this.data[this.tos];
	}

	public void display() {
		System.out.println("---------------------------------------------");
		for (int i = this.tos; i >=0; i--) {
			System.out.print(this.data[i] +" ");	
		}
		System.out.println(".");
		System.out.println("----------------------------------------------");
		
	}

}