如何防止 date.getMillisOf null 指針異常？

Question

oldScoreByPriorityMap.get(key).getCalculationDate()有問題。 如何防止millis在這一段拋出null指針異常？

例外

[29.05.2020 17|callto:29.05.2020 17]:01:37,619 ERROR java.lang.NullPointerException
java.lang.NullPointerException
        at java.util.Date.getMillisOf(Date.java:958)
        at java.util.Date.after(Date.java:931)
        at tr.com.model.report.objects.ReportTableObject.setOldScoreByPriorityMap(ReportTableObject.java:80)
        at tr.com.model.report.objects.ReportTableObject.setCpty(ReportTableObject.java:26)

RaportTableObject.java

    String key = scoreByPriority.getRuleEngineSetup().getName();
    if(oldScoreByPriorityMap.containsKey(scoreByPriority.getRuleEngineSetup().getName())) {
        if(scoreByPriority.getCalculationDate()!=null && scoreByPriority.getCalculationDate().after(oldScoreByPriorityMap.get(key).getCalculationDate()))
            oldScoreByPriorityMap.put(key, scoreByPriority);
    }else {
        oldScoreByPriorityMap.put(key, scoreByPriority);
    }

日期.java

public boolean after(Date when) {
    return getMillisOf(this) > getMillisOf(when);
}

Answer 1

這可能對你有幫助

    String key = scoreByPriority.getRuleEngineSetup().getName();
    if(oldScoreByPriorityMap.containsKey(scoreByPriority.getRuleEngineSetup().getName()) && oldScoreByPriorityMap.get(key).getCalculationDate() != null) {
        if(scoreByPriority.getCalculationDate() != null && scoreByPriority.getCalculationDate().after(oldScoreByPriorityMap.get(key).getCalculationDate()))
            oldScoreByPriorityMap.put(key, scoreByPriority);
    }else {
        oldScoreByPriorityMap.put(key, scoreByPriority);
    }