In this case an instance lock is acquired four times: three times for the append method and one time for the toString method, right after another.

在上面的例子中，锁的实例会被请求四次：前三次是执行append方法，最后一次是执行toString方法，紧接着前一个。

youdao

In this case an instance lock is acquired four times: three times for the append method and one time for the toString method, right after another.

在上面的例子中，锁的实例会被请求四次：前三次是执行append方法，最后一次是执行toString方法，紧接着前一个。

youdao