java">package com.data.entity;

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

public class MyList {
    public List<Integer> list=new ArrayList<>();

    //同步方法 线程锁
    //public synchronized void  insert(int i){
    public void  insert(int i){
        list.add(i);
    }

    public void query(){
        System.out.println("长度："+list.size());
        for (int i = 0; i < list.size(); i++) {
            System.out.println(list.get(i));
        }
    }

}

java">import com.data.entity.MyList;

public class text8 {
    public static void main(String[] args)throws Exception {
        MyList m=new MyList();
        Thread t1=new Thread(()->{
            synchronized (m) {   //同步代码块 线程琐
                for (int i = 1; i <= 5; i++) {
                    m.insert(i);
                }
            }
        });
        Thread t2=new Thread(()->{
            synchronized (m) {   //同步代码块 线程琐
                for (int i = 6; i <= 10; i++) {
                    m.insert(i);
                }
            }
        });

        t1.start();
        t2.start();

        t1.join();
        t2.join();

        m.query();
    }
}

区别

1. 同步方法: 线程执行需要同时争抢时间片和锁标记,写法简单但效率较慢

2. 同步代码块: 线程只需要争抢时间片, 开启互斥锁的线程默认拥有锁标记, 效率较快但写法相对繁琐