public class Test {

public static void main(String[] args) {
    Runnable runnable = new Runnable() {
        private int count = 0;
        @Override
        public void run() {
            try {
                for (int i = 0; i < 10; i++) {
                    System.out.println(count++);
                    Thread.sleep(100);
                }
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    };

    Thread a = new Thread(runnable);
    a.start();
    Thread b = new Thread(runnable);
    b.start();
}

}
=========================console========================
0
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16
===================================================
println方法是使用synchronized修饰的同步方法，为什么还会出现这种数据count不同步的情况？