默认构造器add

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.UUID;
public class Demo {
    public static void main(String[] args) {
        List<String> arrayList = new ArrayList<>();
        List<String> linkedList = new LinkedList<>();
        int length = 10000000;
        long start = System.currentTimeMillis();
        for (int i = 0; i < length; i++) {
            arrayList.add(UUID.randomUUID().toString());
        }
        long end = System.currentTimeMillis();
        System.out.println("ArrayList耗时：" + (end - start));
        start = System.currentTimeMillis();
        for (int i = 0; i < length; i++) {
            linkedList.add(UUID.randomUUID().toString());
        }
        end = System.currentTimeMillis();
        System.out.println("linkedList耗时：" + (end - start));
    }
}

ArrayList耗时：10122 linkedList耗时：12241

分析：
ArrayList越大的时候扩容后就越大，添加元素以后扩容次数就越少。
LinkedList 每次都要创建节点 Node.

默认构造器指定位置add

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.UUID;
public class ClassLoaderDemo {e
    public static void main(String[] args) {
        List<String> arrayList = new ArrayList<>();
        List<String> linkedList = new LinkedList<>();
        int length = 100000;
        long start = System.currentTimeMillis();
        for (int i = 0; i < length; i++) {
            arrayList.add(0, UUID.randomUUID().toString());
        }
        long end = System.currentTimeMillis();
        System.out.println("ArrayList耗时：" + (end - start));
        start = System.currentTimeMillis();
        for (int i = 0; i < length; i++) {
            linkedList.add(0, UUID.randomUUID().toString());
        }
        end = System.currentTimeMillis();
        System.out.println("linkedList耗时：" + (end - start));
    }
}

ArrayList耗时：1125 linkedList耗时：53

分析：
ArrayList 指定位置添加 后面的元素会复制向后移动一位。
LinkedList 只是节点指向变化。