java：模拟栈操作

 import java.util.ArrayList;

 public class MyStack {

     private ArrayList<Object> arrayList;

     public MyStack() {
         arrayList = new ArrayList<>();
     }

     public void pop(Object o) {
         arrayList.add(o);
     }

     public Object myRamove() {
         int size = arrayList.size();
         if (size > 0) {
             return arrayList.remove(arrayList.size() - 1);
         }else {
             return -1;
         }
     }
     public int getSize() {
         return arrayList.size();
     }

 }