java中如何实现同步或锁定变量呢？

实现思路:
    使用synchronized关键字即可锁定变量

 
class TestClass {
    private String info = null;
    private final Object lock = new Object();

    public void newInfo(String x) {
        synchronized (lock) {
            info = x;
        }
    }

    public String getInfo() {
        synchronized (lock) {
            String temp = info;
            info = null;
            return temp;
        }
    }
}