StackImpl.java

package hw1;

public class StackImpl {
private ArrayListImpl elementData = new ArrayListImpl();
	
	public void push(Object o){	
		elementData.add(o);
	}
	
	public Object pop(){
		return elementData.remove(elementData.size() - 1);
	}
	
	public Object peek(){
		return elementData.get(elementData.size() - 1);
	}
	public boolean isEmpty(){
		return elementData.size() == 0;
	}
	public int size(){
		return elementData.size();
	}
}