Sync Lock (Lock)

There are two mechanisms to prevent code blocks from being disturbed by concurrent access:

1, one is to use the Synchronized keyword.

2, use Reentrantlock class. (Synchronization is achieved by displaying the definition of a synchronization lock object.) )

The Synchronous Lock (Lock) method is a tool that controls the access of multiple threads to shared resources. Typically, a lock provides exclusive access to a shared resource, and only one thread can lock the lock object at a time, and the thread obtains the lock object before it begins accessing the shared resource.

Lock, Readwritelock (read-write lock) is the two root interface provided by Java 5. Do not provide a reentrantlock (Reentrant lock) implementation class for the lock interface, and a Reentrantreadwritelock implementation class for the Readwritelock interface.

In the implementation of thread-safe control, the more commonly used is reentrantlock (can be re-entry lock). Use this lock object to display a lock and release lock.

1 ImportJava.util.*;2 ImportJava.util.concurrent.locks.ReentrantLock;3  Public classOtherextendsthread{4     PrivateAccount account ;5     Private DoubleDrawamount;6     //private String name;7      PublicOther (account account,Doubledrawamount,string name) {8         Super(name);//must be the first statement9          This. account=Account ;Ten          This. drawamount=Drawamount; One start (); A     } -      Public voidrun () { -          for(inti=0;i<15;i++){ the Account.draw (drawamount); -         } -     } -      Public Static voidMain (string[] args) { +Account A=NewAccount ("Liu Teng", 10000); -Other o=NewOther (a,1000, "a"); +Thread t=NewThread (NewRunnableclass (a)); AT.setname ("B"); at T.start (); -     } - } - classaccount{ -     //Defining Lock Objects -     Private FinalReentrantlock lock=NewReentrantlock (); in     PrivateString name; -     Private DoubleMoney ; to      PublicAccount () {} +      PublicAccount (String name,DoubleMoney ) { -          This. name=name; the          This. money=Money ; *     } $      Public DoubleGetmoney () {Panax Notoginseng Lock.lock (); -         Try{ the         returnMoney ;} +         finally{ A Lock.unlock (); the         } +     } -      Public voidDrawDoubleDrawamount) { $ Lock.lock (); $         Try{ -             if(money>=Drawamount) { -SYSTEM.OUT.PRINTLN (name + "Withdraw money success!") Spit out the money: "+drawamount); the                 Try{ -Thread.Sleep (1000);Wuyi}Catch(Exception e) { the System.out.println (e); -                 } Wumoney-=Drawamount; -System.out.println ("Balance:" +Getmoney ()); About}Else{ $System.out.println ("The money failed!") Insufficient balance! "); -             } -}finally{ - Lock.unlock (); A         } +     } the } - classRunnableclassImplementsrunnable{ $     PrivateAccount account ; the     //private double drawamount; the      PublicRunnableclass (account account) { the          This. account=Account ; the         //This.drawamount=drawamount; -     } in      Public voidrun () { the          for(intk=0;k<10;k++){ the         Try{ AboutThread.Sleep (1000); theSystem.out.println (Thread.CurrentThread (). GetName () + "read money:" +Account.getmoney ());} the         Catch(Exception e) {} the         } +     } -}

Importing import java.util.concurrent.locks.ReentrantLock is required;

Sync Lock (Lock)