Java multi-thread visibility and atomicity--synchronized VS volatile

Examples of programs:

Code:

Package Com.synch;public class Synchronizeddemo {//Shared variable private Boolean ready = false;    private int result = 0;       private int number = 1;          Write operation public synchronized void write () {ready = true;                           Number = 2;     }//read operation public synchronized void read () {if (ready) {result = Number*3;    } System.out.println ("The value of result is:" + result); }//Internal thread class private class Readwritethread extends thread {///depending on the flag parameter passed in the constructor method, determines whether the thread performs a read or write operation Private Boolean FLA    G    Public Readwritethread (Boolean flag) {This.flag = flag; } @Override public void Run () {i        The f (flag) {///constructor method passes in true, performing write writes ();        }else{//construct method to pass in false, perform read operation reading ();    }}} public static void Main (string[] args) {Synchronizeddemo Syndemo = new Synchronizeddemo (); Initiates a thread to perform a write operation Syndemo. New Readwritethread (True). Start ();//try {//thread.sleep (+),//} catch (Interruptedexception e) {////TODO auto-generated catch Block//e.pri    Ntstacktrace ();///start thread to perform read operation Syndemo.new Readwritethread (FALSE). Start (); }}

code example:

package com.synch;import Java.util.concurrent.locks.lock;import Java.util.concurrent.locks.reentrantlock;public class Volatiledemo {private lock lock = new Reentrantlock ();p rivate int Number = 0;public int GetNumber () {return this.number;} public void Increase () {try {thread.sleep ()} catch (Interruptedexception e) {//TODO auto-generated catch Blocke.print StackTrace ();} Lock.lock (); try {this.number++;} finally {Lock.unlock ();}}  /** * @param args */public static void main (string[] args) {//TODO auto-generated method stubfinal Volatiledemo Voldemo = New Volatiledemo (); for (int i = 0; i < i++) {new Thread (new Runnable () {@Overridepublic void run () {Voldemo.incre ASE ();}}). Start ();} If there are sub-threads running, the main thread will let the CPU resources,//until all the sub-threads are running, and the main thread continues to execute while (Thread.activecount () > 1) {//Let all child threads execute, then execute <   Pre name= "code" class= "Java" >//system.out.println ("number:" + voldemo.getnumber ()); Statement. Because the main thread counts one. When the active thread is 1 o'clock, that is, all of the child threads have finished executing. This///exits the while loop to execute the output statement. 

Thread.yield ();} System.out.println ("Number:" + voldemo.getnumber ());}}

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Java multi-thread visibility and atomicity--synchronized VS volatile