java INT-type thread safety

One, test int is thread unsafe

In Java, in the case of high concurrency/multithreading, the self-subtraction of int is not thread-safe, and the use of Atomicinteger can be guaranteed.

Package com.yezi.learn.atomic;
Import Java.util.concurrent.atomic.AtomicInteger;
 /** * Created by Yezi on 2014/5/10.
    * * Public class Testatomicinteger {private int sharei=0;
    Private Atomicinteger Atomicloop = new Atomicinteger (0);
    private int loop = 0;
        public static void Main (String []args) throws exception{Testatomicinteger t = new Testatomicinteger ();
        T.testmethod ();
    System.out.println (t);
        The public void TestMethod () throws exception{thread Th1 = new Thread (new ThreadTest ());
        Thread Th2 = new Thread (new ThreadTest ());
        Th1.start ();
        Th2.start ();
        Th1.join ();
    Th2.join ();
    Public synchronized void Add () {sharei++; Class ThreadTest implements runnable{@Override public void Run () {//testatomicinteger (
            );
        Testint (); } public void Testint () {//test, Output random, for thread unsafe for (; loop<100000;loop++) {ADD (); } public void Testatomicinteger () {//output 1000000, thread safe for (; Atomicloop.getandadd (1) <100000;)
        {Add ();
    @Override public String toString () {return "+sharei;
 }
}

Second, Atomicintegerfieldupdater can be processed on the fields of obj

Package com.yezi.learn.atomic;
Import Java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
 /** * Created by Yezi on 2014/5/10.
    * * Public class Testatomicobjectinteger {private Looper looper = new Looper ();
    private int sharei=0; public static void Main (String ... args) throws exception{Testatomicobjectinteger t = new Testatomicobjectinteger (
        );
        T.testmethod ();
    System.out.println (t);
            public void Testnormal () {//thread unsafe for (; Looper.getloop () <100000;looper.setloop (Looper.getloop () +1)) {
        Add (); } public void Testuseatomic () {atomicintegerfieldupdater<looper> Atomicintegerfieldupdater =//Use
        Atomic to Atomicintegerfieldupdater.newupdater (Looper.class, "loop");
        for (; Atomicintegerfieldupdater.getandadd (looper,1) <100000;) {Add ();
        The public void TestMethod () throws exception{thread Th1 = new Thread (new ThreadTest ()); ThreAd Th2 = new Thread (new ThreadTest ());
        Th1.start ();
        Th2.start ();
        Th1.join ();
    Th2.join ();
            Class ThreadTest implements runnable{@Override public void Run () {testuseatomic ();
        Testnormal ();
    } public synchronized void Add () {sharei++;
    @Override public String toString () {return sharei+ "";  Class looper{public volatile int loop=0;
    The field to be controlled for atomicintegerfieldupdater must be public volatile public int Getloop () {return loop;
    public void Setloop (int loop) {This.loop = loop;
 }
}