java：模拟栈操作

 1 import java.util.ArrayList;
 2 
 3 public class MyStack {
 4 
 5     private ArrayList< > arrayList;
 6 
 7     public MyStack() {
 8         arrayList = new ArrayList<>();
 9     }
10 
11     public void pop(  o) {
12         arrayList.add(o);
13     }
14 
15     public   myRamove() {
16         int size = arrayList.size();
17         if (size > 0) {
18             return arrayList.remove(arrayList.size() - 1);
19         }else {
20             return -1;
21         }
22     }
23     public int getSize() {
24         return arrayList.size();
25     }
26 
27 }