Android 多线程保证操作同步(同步锁的俩种)

synchronized这个关键字可以直接加到方法上也可使用synchronized代码块，将需要同步的代码放到这个代码块中，如:

private synchronized void writeLog() {
    for (int i = 0; i < 3; i++) {
        try {
            Log.e(TAG, "showLog: " + Thread.currentThread().getName() + "写入中");
            Thread.sleep(new Random().nextInt(1000));
            Log.e(TAG, "showLog: " + Thread.currentThread().getName() + "写入完成");
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

private void readLog() {
    synchronized (this) {
        for (int i = 0; i < 3; i++) {
            try {
                Log.e(TAG, "showLog: " + Thread.currentThread().getName() + "读取中");
                Thread.sleep(new Random().nextInt(1000));
                Log.e(TAG, "showLog: " + Thread.currentThread().getName() + "读取完成");
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}