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????Volatile?????

Volatile?Java????????????????????????????????????????????????????????????????????????????????Volatile?????????????????????????

Volatile???

Volatile?????

• ??????????????Volatile?????????????????????
• ???????????????????Volatile???????????????????

Volatile?Synchronized???

• Volatile???????????????????????????????Volatile???
• Synchronized??????????????????????????

Lock????????

?Java????????Lock??????????????????synchronized???????????????????????????Lock??????????????????????ReentrantLock?

ReentrantLock???

• ???????????????????????
• fairness???????????????????
• blocking???????????????????

Lock?????

• ??synchronized????????????Lock????????????
• ?????Lock??????????????????????

?????????

?????????????????????????????????????????????????????????????????????????????????

???

• ???????????????????????????????????????????????????
• ??????????????????
• ???????????????????

????

• ???????????????????????????????????
• ??????????????????
• ????????????????

????

?????Volatile?Lock??????????

public class Demo {    private volatile int a = 1;    private Lock lock = new ReentrantLock();    public int getA() {        lock.lock();        return a;    }    public void setA(int a) {        lock.lock();        try {            Thread.sleep(2);        } catch (InterruptedException e) {            e.printStackTrace();        }        this.a = a;        lock.unlock();    }    public static void main(String[] args) {        Demo d = new Demo();        d.a = 10;        new Thread(new Runnable() {            @Override            public void run() {                System.out.println(d.a);            }        }).start();        try {            Thread.sleep(100);        } catch (InterruptedException e) {            e.printStackTrace();        }        System.out.println("??????" + d.getA());    }}

??

Volatile?Lock???Java???????????Volatile?????????????????Lock????????????????????????????????????????????

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