关于ArrayList和LinkedList的插入，遍历，删除时间比照

以下是代码块：

package list;

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;

public class ListAdd {

    public static void main(String[] args) {
        testQuery();
    }

    static void testAdd() {
        Object object = new Object();
        List<Object> al = new ArrayList<>(); // 70ms
        List<Object> ll = new LinkedList<>(); // 471ms
        long b = System.currentTimeMillis();
        for (int i = 0; i < 5000000; i++) {
            al.add(object); // 添加到尾端
        }
        long e = System.currentTimeMillis();
        System.out.println(e - b);
    }

    static void testAddIndex() {
        Object object = new Object();
        List<Object> al = new ArrayList<>(); // 1071ms
        List<Object> ll = new LinkedList<>(); // 17ms
        long b = System.currentTimeMillis();
        for (int i = 0; i < 100000; i++) {
            ll.add(0, object); // 添加到尾端
        }
        long e = System.currentTimeMillis();
        System.out.println(e - b);
    }

    static void testQuery() {
        List<String> l = new ArrayList<>();
        for (int i = 0; i < 1000000; i++) {
            l.add(String.valueOf(i));
        }
        long b = System.currentTimeMillis();
        String temp = "";
        for (int i = 0; i < l.size(); i++) {
            temp = l.get(i);
        }
        long e = System.currentTimeMillis();
        System.out.println(e - b);
    }
}