public class ArrayListDemo {
    public static void main(String[] args) {
        int size = 2000000;
        List<String> list = new ArrayList<>();
        for(int i = 0;i<size;i++) {
            list.add("Just some test data");
        }

        long startTime = System.currentTimeMillis();
        for(int i = 0;i<size;i++) {
            list.get(i);
            if(i%10000 ==0) {
                System.out.println("query 10000 elements spend: "+ (System.currentTimeMillis()-startTime));
                startTime = System.currentTimeMillis();
            }
        }
    }
}

程序运行结果：

query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 10
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0
query 10000 elements spend: 0

......
和LinkedListWorngDemo对比可以充分说明一个问题