volatile和synchronized对比

package com.company.bingfa;

class MyThread7 extends Thread{
//    public static volatile int n;
    public static int n;
    private static synchronized void increase(){
        n++;
    }

    @Override
    public void run() {
        for (int i = 0; i < 10; i++) {
//            n = n + 1;
            increase();
            try {
                sleep(3);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}

public class ThreadJoin2 {
    public static void main(String[] args) throws InterruptedException {
        Thread[] ts = new Thread[100];
        for (int i = 0; i < 100; i++) {
            ts[i] = new MyThread7();
        }
        for (int i = 0; i < 100; i++) {
            ts[i].start();
        }
        for (int i = 0; i < 100; i++) {
            ts[i].join();
        }
        System.out.println(MyThread7.n);
    }

}