這個 try-catch 是如何工作的？

Question

我正在閱讀的Java 代碼是：

    private void validateCoordinatorJob() throws Exception {
        // check if startTime < endTime
        if (!coordJob.getStartTime().before(coordJob.getEndTime())) {
            throw new IllegalArgumentException("Coordinator Start Time must be earlier than End Time.");
        }

        try {
            // Check if a coord job with cron frequency will materialize actions
            int freq = Integer.parseInt(coordJob.getFrequency());

            // Check if the frequency is faster than 5 min if enabled
            if (ConfigurationService.getBoolean(CONF_CHECK_MAX_FREQUENCY)) {
                CoordinatorJob.Timeunit unit = coordJob.getTimeUnit();
                if (freq == 0 || (freq < 5 && unit == CoordinatorJob.Timeunit.MINUTE)) {
                    throw new IllegalArgumentException("Coordinator job with frequency [" + freq +
                            "] minutes is faster than allowed maximum of 5 minutes ("
                            + CONF_CHECK_MAX_FREQUENCY + " is set to true)");
                }
            }
        } catch (NumberFormatException e) {
            Date start = coordJob.getStartTime();
            Calendar cal = Calendar.getInstance();
            cal.setTime(start);
            cal.add(Calendar.MINUTE, -1);
            start = cal.getTime();

            Date nextTime = CoordCommandUtils.getNextValidActionTimeForCronFrequency(start, coordJob);
            if (nextTime == null) {
                throw new IllegalArgumentException("Invalid coordinator cron frequency: " + coordJob.getFrequency());
            }
            if (!nextTime.before(coordJob.getEndTime())) {
                throw new IllegalArgumentException("Coordinator job with frequency '" +
                        coordJob.getFrequency() + "' materializes no actions between start and end time.");
            }
        }
    }

我沒有得到的是"Coordinator job with frequency [" + freq + "] minutes is faster than allowed maximum of 5 minutes ("+ CONF_CHECK_MAX_FREQUENCY + " is set to true)"日志是否可以打印。

據我所知，當if (freq == 0 || (freq < 5 && unit == CoordinatorJob.Timeunit.MINUTE))條件滿足並且程序拋出 IllegalArgumentException 時。 拋出的異常將在catch (NumberFormatException e)處被捕獲，並在該塊中作為e處理。

但是那個e之后再也沒有使用過。

所以我想知道是否可以按Coordinator job with frequency...日志。

對我來說，原始代碼與將 catch 塊放入if (freq == 0 || (freq < 5 && unit == CoordinatorJob.Timeunit.MINUTE))語句之間似乎沒有區別，如下所示：

    private void validateCoordinatorJob() throws Exception {
        // check if startTime < endTime
        if (!coordJob.getStartTime().before(coordJob.getEndTime())) {
            throw new IllegalArgumentException("Coordinator Start Time must be earlier than End Time.");
        }

        // Check if a coord job with cron frequency will materialize actions
        int freq = Integer.parseInt(coordJob.getFrequency());

        // Check if the frequency is faster than 5 min if enabled
        if (ConfigurationService.getBoolean(CONF_CHECK_MAX_FREQUENCY)) {
            CoordinatorJob.Timeunit unit = coordJob.getTimeUnit();
            if (freq == 0 || (freq < 5 && unit == CoordinatorJob.Timeunit.MINUTE)) {
                Date start = coordJob.getStartTime();
                Calendar cal = Calendar.getInstance();
                cal.setTime(start);
                cal.add(Calendar.MINUTE, -1);
                start = cal.getTime();

                Date nextTime = CoordCommandUtils.getNextValidActionTimeForCronFrequency(start, coordJob);
                if (nextTime == null) {
                    throw new IllegalArgumentException("Invalid coordinator cron frequency: " + coordJob.getFrequency());
                }
                if (!nextTime.before(coordJob.getEndTime())) {
                    throw new IllegalArgumentException("Coordinator job with frequency '" +
                            coordJob.getFrequency() + "' materializes no actions between start and end time.");
                }
            }
        }
    }

Answer 1

catch 捕獲NumberFormatException ，而不是IllegalArgumentException ，因此它不會捕獲throw語句中拋出的異常。 NumberFormatException繼承自IllegalArgumentException的事實並不重要。 catch子句在inheritance 樹中捕獲異常，而不是向上。 如果一個人可以接住所有的Tennisball ，而你向他們扔一個普通的Ball ，他們不會接住它，不是嗎？

假設try子句中的其他方法沒有拋出NumberFormatException ，那么catch子句旨在捕獲Integer.parseInt拋出的NumberFormatException 。

所以我想知道是否可以按頻率打印協調員工作......日志。

它可以由另一種方法打印出來，該方法在調用堆棧中進一步捕獲異常。