要反转 ArrayList，可以使用 Collections 类的 reverse() 方法。参考以下示例。

import java.util.ArrayList;  
import java.util.Collection;  
import java.util.Collections;  
import java.util.Iterator;  
import java.util.List;  
public class ReverseArrayList {  
public static void main(String[] args) {  
     List list = new ArrayList<>();  
     list.add(10);  
     list.add(50);  
     list.add(30);  
     Iterator i = list.iterator();  
     System.out.println("printing the list....");  
     while(i.hasNext())  
     {  
         System.out.println(i.next());  
     }  
     Iterator i2 = list.iterator();  
     Collections.reverse(list);  
     System.out.println("printing list in reverse order....");  
     while(i2.hasNext())  
     {  
         System.out.println(i2.next());  
     }  
    }  
}

运行结果如下：

printing the list....
10
50
30
printing list in reverse order....
30
50
10