04 traditional synchronized lock

3、Lock lock （ a key ）

In the traditional way synchronized

04- Conventional Synchronized lock

1. An example of buying a ticket

package com.hkx.demo01;

/** * @program: juc * @description:  An example of buying a ticket  * @author: Casey Hu * @create: 2022-07-24 19:11 **/

/*** *  True multithreaded development   Development in the company  *  Thread is a separate resource class , There is no ancillary operation  * 1. attribute   Method  */
public class SaleTicketDemo01 {
    
    public static void main(String[] args) {
    
        new Thread(new MyThread()).start();
    }
}

class MyThread implements Runnable{
    
    @Override
    public void run(){
    

    }
}

2. Thread is a separate resource class , There is no ancillary operation

Runnable() Belong to ： Functional interface @FunctionalInterface
Anonymous inner class new Runable()

package com.hkx.demo01;

/** * @program: juc * @description:  An example of buying a ticket  * @author: Casey Hu * @create: 2022-07-24 19:11 **/

/*** *  True multithreaded development   Development in the company  *  Thread is a separate resource class , There is no ancillary operation  * 1. attribute   Method  */
public class SaleTicketDemo01 {
    
    public static void main(String[] args) {
    
        // Concurrent ： Multiple threads operate on the same resource class , Drop resource class into thread 
        Ticket ticket=new Ticket(); // Resource class 

        // Functional interface @FunctionalInterface ,jdk1.8 after  lambda expression  ( Parameters )->{ Code }
        new Thread(()-> {
    
            // Three threads   Methods of operating resources 
            for (int i=0;i<60;i++){
    
                ticket.sale();
            }
        },"A").start();

        new Thread(()-> {
    
            for (int i=0;i<60;i++){
    
                ticket.sale();
            }
        },"B").start();

        new Thread(()-> {
    
            for (int i=0;i<60;i++){
    
                ticket.sale();
            }
        },"C").start();

    }
}

// Resource class  OOP Development 
class Ticket{
    
    // attribute   and   Method 
    private int number=50;

    // How to buy tickets 
    // synchronized  The essence  ： queue   lock 
    public synchronized void sale(){
    
        if (number>0){
    
            System.out.println(Thread.currentThread().getName()+" Sold No "+(number--)+" Tickets , The remaining ："+number);
        }
    }
}

Output log ：

"D:\Program Files (x86)\Java\jdk1.8.0_144\bin\java.exe" "-javaagent:D:\Program Files (x86)\JetBrains\IntelliJ IDEA 2022.1.3\lib\idea_rt.jar=58815:D:\Program Files (x86)\JetBrains\IntelliJ IDEA 2022.1.3\bin" -Dfile.encoding=UTF-8 -classpath "D:\Program Files (x86)\Java\jdk1.8.0_144\jre\lib\charsets.jar;D:\Program Files (x86)\Java\jdk1.8.0_144\jre\lib\deploy.jar;D:\Program Files (x86)\Java\jdk1.8.0_144\jre\lib\ext\access-bridge-64.jar;D:\Program Files (x86)\Java\jdk1.8.0_144\jre\lib\ext\cldrdata.jar;D:\Program Files (x86)\Java\jdk1.8.0_144\jre\lib\ext\dnsns.jar;D:\Program Files (x86)\Java\jdk1.8.0_144\jre\lib\ext\jaccess.jar;D:\Program Files (x86)\Java\jdk1.8.0_144\jre\lib\ext\jfxrt.jar;D:\Program Files (x86)\Java\jdk1.8.0_144\jre\lib\ext\localedata.jar;D:\Program Files (x86)\Java\jdk1.8.0_144\jre\lib\ext\nashorn.jar;D:\Program Files (x86)\Java\jdk1.8.0_144\jre\lib\ext\sunec.jar;D:\Program Files (x86)\Java\jdk1.8.0_144\jre\lib\ext\sunjce_provider.jar;D:\Program Files (x86)\Java\jdk1.8.0_144\jre\lib\ext\sunmscapi.jar;D:\Program Files (x86)\Java\jdk1.8.0_144\jre\lib\ext\sunpkcs11.jar;D:\Program Files (x86)\Java\jdk1.8.0_144\jre\lib\ext\zipfs.jar;D:\Program Files (x86)\Java\jdk1.8.0_144\jre\lib\javaws.jar;D:\Program Files (x86)\Java\jdk1.8.0_144\jre\lib\jce.jar;D:\Program Files (x86)\Java\jdk1.8.0_144\jre\lib\jfr.jar;D:\Program Files (x86)\Java\jdk1.8.0_144\jre\lib\jfxswt.jar;D:\Program Files (x86)\Java\jdk1.8.0_144\jre\lib\jsse.jar;D:\Program Files (x86)\Java\jdk1.8.0_144\jre\lib\management-agent.jar;D:\Program Files (x86)\Java\jdk1.8.0_144\jre\lib\plugin.jar;D:\Program Files (x86)\Java\jdk1.8.0_144\jre\lib\resources.jar;D:\Program Files (x86)\Java\jdk1.8.0_144\jre\lib\rt.jar;E:\IdeaProjects\juc\juc\target\classes;D:\Maven\repository\org\projectlombok\lombok\1.18.8\lombok-1.18.8.jar" com.hkx.demo01.SaleTicketDemo01
A Sold No 50 Tickets , The remaining ：49
A Sold No 49 Tickets , The remaining ：48
A Sold No 48 Tickets , The remaining ：47
B Sold No 47 Tickets , The remaining ：46
B Sold No 45 Tickets , The remaining ：44
B Sold No 44 Tickets , The remaining ：43
A Sold No 46 Tickets , The remaining ：45
A Sold No 42 Tickets , The remaining ：41
A Sold No 41 Tickets , The remaining ：40
A Sold No 40 Tickets , The remaining ：39
A Sold No 39 Tickets , The remaining ：38
A Sold No 38 Tickets , The remaining ：37
B Sold No 43 Tickets , The remaining ：42
B Sold No 35 Tickets , The remaining ：34
B Sold No 34 Tickets , The remaining ：33
B Sold No 33 Tickets , The remaining ：32
B Sold No 32 Tickets , The remaining ：31
B Sold No 31 Tickets , The remaining ：30
B Sold No 30 Tickets , The remaining ：29
B Sold No 29 Tickets , The remaining ：28
B Sold No 28 Tickets , The remaining ：27
B Sold No 27 Tickets , The remaining ：26
B Sold No 26 Tickets , The remaining ：25
B Sold No 25 Tickets , The remaining ：24
B Sold No 24 Tickets , The remaining ：23
B Sold No 23 Tickets , The remaining ：22
B Sold No 22 Tickets , The remaining ：21
B Sold No 21 Tickets , The remaining ：20
B Sold No 20 Tickets , The remaining ：19
B Sold No 19 Tickets , The remaining ：18
B Sold No 18 Tickets , The remaining ：17
B Sold No 17 Tickets , The remaining ：16
B Sold No 16 Tickets , The remaining ：15
B Sold No 15 Tickets , The remaining ：14
B Sold No 14 Tickets , The remaining ：13
B Sold No 13 Tickets , The remaining ：12
B Sold No 12 Tickets , The remaining ：11
A Sold No 36 Tickets , The remaining ：35
A Sold No 10 Tickets , The remaining ：9
A Sold No 9 Tickets , The remaining ：8
A Sold No 8 Tickets , The remaining ：7
A Sold No 7 Tickets , The remaining ：6
A Sold No 6 Tickets , The remaining ：5
A Sold No 5 Tickets , The remaining ：4
A Sold No 4 Tickets , The remaining ：3
A Sold No 3 Tickets , The remaining ：2
A Sold No 2 Tickets , The remaining ：1
A Sold No 1 Tickets , The remaining ：0
C Sold No 37 Tickets , The remaining ：36
B Sold No 11 Tickets , The remaining ：10

 Process ended , Exit code 0

Lock lock

Lock Interface

Lock The three implementation classes of the interface

SaleTicketDemo02

Fair lock ： Processing thread fairness , first come , first served
Not fair lock ： Processing threads are unfair , according to CPU Resources can jump the queue （ Default unfair lock ）

package com.hkx.demo01;

import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

/** * @program: juc * @description:  An example of selling tickets  * @author: Casey Hu * @create: 2022-07-25 21:55 **/

public class SaleTicketDemo02 {
    
    public static void main(String[] args) {
    
        // Concurrent ： Multiple threads operate on the same resource class , Drop resource class into thread 
        Ticket2 ticket = new Ticket2(); // Resource class 
        new Thread(() -> {
    
            for (int i = 0; i < 60; i++) ticket.sale();
        }, "A").start();
        new Thread(() -> {
    
            for (int i = 0; i < 60; i++) ticket.sale();
        }, "B").start();
        new Thread(() -> {
    
            for (int i = 0; i < 60; i++) ticket.sale();
        }, "C").start();

    }
}

//Lock
class Ticket2 {
    
    private int number = 50;
    Lock lock = new ReentrantLock();

    /*** * 1.new ReentrantLock() * 2.lock();  Lock  * 3.unlock();  Unlock  */
    public void sale() {
    

        lock.lock(); // Lock 
        try {
    
            // Business code 
            if (number > 0) {
    
                System.out.println(Thread.currentThread().getName() + " Sold No " + (number--) + " Tickets , The remaining ：" + number);
            }
        } finally {
    
            lock.unlock(); // Unlock 
        }
    }
}

synchronized and Lock What's the difference