package week1.collections;
public class Stack {
private ArrayList elementData = new ArrayList();
public void push(Object o){
elementData.add(o);
}
public Object pop(){
Object o = elementData.remove(elementData.size()-1);
return o;
}
public Object peek(){
Object o = elementData.get(elementData.size()-1);
return o;
}
public boolean isEmpty(){
return elementData.size()==0;
}
public int size(){
return elementData.size();
}
}