package test05.stack;
import java.util.ArrayList;
public class Stack<T> {
private ArrayList<T> elementData = new ArrayList<T>();
public void push(T o){
elementData.add(o);
}
public T pop(){
return elementData.remove(size()-1);
}
public T peek(){
if (size()>0) {
return elementData.get(size()-1);
} else {
return null;
}
}
public boolean isEmpty(){
return elementData.size()==0;
}
public int size(){
return elementData.size();
}
@Override
public String toString() {
StringBuffer sb=new StringBuffer();
while (peek()!=null) {
sb.append(pop()).append(",");
}
return sb.substring(0, sb.length()-1);
}
}