Mode 1-singlethreadexecution

Come to Java multi-thread design mode

I. Method: Use the Synchronized Method to allow only one pass at a time.

 Public   Class Userthread Extends Thread { Private   Final Gate; Private   Final String myname; Private   Final String myaddress; Public Userthread (gate, string myname, string myaddress ){ This . Gate = gate;This . Myname = myname; This . Myaddress = myaddress ;} Public   Void Run () {system. Out. println (myname +" Begin "); While ( True ) {Gate. Pass (myname, myaddress );}}}

 Public   Class Gate { Private   Int Counter = 0; Private String name =" Nobody "; Private String address =" Nowhere "; Public   Void Pass (string name, string address ){ This . Counter ++; This . Name = Name; This . Address = address; check ();} Public String tostring (){ Return " No. "+ Counter +": "+ Name +" , "+ Address ;} Private   Void Check (){ If (Name. charat (0 )! = Address. charat (0) {system. Out. println (" * ***** Broken ***** "+ Tostring ());}}}

 
Only one pass at a time:
 

 Public   Class Gate { Private   Int Counter = 0; Private String name ="Nobody "; Private String address =" Nowhere "; Public Synchronized VoidPass (string name, string address) { This . Counter ++; This . Name = Name; This . Address = address; check ();} Public SynchronizedString tostring () { Return "No. "+ Counter +" : "+ Name +" , "+ Address ;} Private   Void Check (){ If (Name. charat (0 )! = Address. charat (0) {system. Out. println (" * ***** Broken ***** "+ Tostring ());}}}

 
Ii. making errors more prone: the delay takes up the time in the critical section:
 

 Public   Class Gate { Private   Int Counter = 0;Private String name =" Nobody "; Private String address =" Nowhere "; Public   Void Pass (string name, string address ){ This . Counter ++; This . Name = Name; Try{Thread. Sleep (1000 );}Catch(Interruptedexception e ){}          This . Address = address; check ();}Public String tostring (){ Return " No. "+ Counter +" : "+ Name +" , "+ Address ;} Private   Void Check (){ If (Name. charat (0 )! = Address. charat (0) {system. Out. println (" * ***** Broken ***** "+ Tostring ());}}}

 
3. avoid deadlocks:
 

 
(1) Multiple shared resources
 

 
(2) try to lock another one if the lock is not released
 

(3) Get a -- get B, or get B -- get a, a/B, with no priority
 

 
A deadlock can be avoided if the preceding one is damaged:
 

 
Public ClassMain {Public Static VoidMain (string [] ARGs) {system. Out. println ("Testing eaterthread, hit Ctrl + C to exit."); Tool spoon =NewTool ("Spoon"); Tool fork =NewTool ("Fork");NewEaterthread ("Alice", Spoon, fork). Start ();NewEaterthread ("Bobby", Fork, spoon). Start ();}}
 

Damage (3 ):

Public ClassMain {

Public Static VoidMain (string [] ARGs ){

System. Out. println ("Testing eaterthread, hit Ctrl + C to exit.");

Tool spoon =NewTool ("Spoon");

Tool fork =NewTool ("Fork");

NewEaterthread ("Alice", Spoon, fork). Start ();

NewEaterthread ("Bobby", Spoon, fork). Start ();

}

}

Get spoon first and then get fork.

 

Damage (1 ):

Change to a shared resource:

  Public   class  main { Public   static   void  main (string [] ARGs) {system. out. println (" testing eaterthread, hit Ctrl + C to exit.  "); tool spoon =  New  tool ("  spoon "); tool fork =  New  tool ("  fork  "); pair pair =  New  pair (Spoon, fork);  New  eaterthread ("  Alice  ", pair ). start ();  New  eaterthread (" Bobby ", pair ). start () ;}

 Public VoidEat (){Synchronized(Pair) {system. Out. println (name +"Takes up"+ Pair +"."); System. Out. println (name +"Is eating now, yam!"); System. Out. println (name +"Puts down"+ Pair +".");}}