java - 关于try/catch block 中变量范围的问题

Question

我有一段代码可能会失败，也可能不会失败，我想在放弃之前尝试 X 次。当它失败时，它会抛出一个特定的异常，所以我认为这样的事情会起作用:

    int retries = 0;
    while (retries < MAX_RETRIES) {
        failedFlag = false;
        try {
            //...do some stuff...
            logger.info("After commit...");
            if (!failedFlag) {
                logger.info("Failed flag is false, so breaking out.");
                break;
            }
        } catch (MyException e) {
            retries++;
            failedFlag = true;
            long sleepMillis = MILLIS_TO_SLEEP * retries;
            logger.warn("Caught a failure");
            logger.warn("Will sleep for " + sleepMillis + "msec and then try again.");
            try {
                Thread.sleep(sleepMillis);
                logger.info("Done sleeping...");
                logger.info("Failed flag is " + (failedFlag ? "true" : "false"));
            } catch (InterruptedException e1) {
                logger.warn("Caught interrupted exception while sleeping.  Terminate.");
                transaction.rollback();
                return;
            }
        }
    }

我遇到的问题是第一个 catch block 中对 failedFlag 所做的更改似乎没有持续存在。失败时，线程会 hibernate ，但是当它醒来并重新进入 try block 时，failedFlag 会恢复为 false？我得到以下日志行:

2010-09-16 17:09:48,448 WARN  [pool-1-thread-1] synchronizer.FlightCreativeSynchronizer - Will sleep for 60000msec and then try again.
...
2010-09-16 17:10:48,449 INFO  [pool-1-thread-1] synchronizer.FlightCreativeSynchronizer - Done sleeping...
2010-09-16 17:10:48,450 INFO  [pool-1-thread-1] synchronizer.FlightCreativeSynchronizer - Failed flag is true
2010-09-16 17:10:48,453 INFO  [pool-1-thread-1] synchronizer.FlightCreativeSynchronizer - After commit...
2010-09-16 17:10:48,453 INFO  [pool-1-thread-1] synchronizer.FlightCreativeSynchronizer - Failed flag is false, so breaking out.

这里有点令人困惑...局部变量是否不受 catch block 中所做的更改的影响？

Answer 1

您在 while 循环的顶部将 failedFlag 设置为 false。