空指針異常Groovy

Question

我得到一個空點異常，並且我的Groovy shell不再指定它發生的位置。這是說，有他們的3，發生在該行scans.each {item ->

如果你敢第一個...：

use(groovy.time.TimeCategory) { 
new File('C:\\Users\\pro-services\\Documents\\ScanEngineDetailFake.log').eachLine { line -> 

    m = line =~ d 
    log = line 
    matcher = (log =~ /\d{2}:\d{2}:\d{2},\d{3}/) 

    matcher.count.times { 
    a = matcher[it] 

    if(a) { 
     if(!prevDate) { 
     prevDate = parseDate(a) 
    } 
    if (line ==~ c){ 
     starts ++ 
     prevDate = parseDate(a) 
    } 
    if (line ==~ d){ 
     finishes ++ 
     def nextDate = parseDate(a) 
     deltas << nextDate - prevDate 
     scans << line 
    } 
    } 
} 

---

def startDate = null 
def finDate = null 
def filediff = null 

76 use(groovy.time.TimeCategory) { 

78 scans.each { item -> 

    logs = item 
    matcher = (logs =~ /\d{2}:\d{2}:\d{2},\d{3}/) 

83 matcher.count.times { 
    b = matcher[it] 

    if (logs ==~ c){ 
     startDate = parseDate(b) 
    } 

    if (logs ==~ d){ 
     finDate = parseDate(b) 

96  filediff = finDate - startDate 

     deltas.each { diff -> 
     if (diff == filediff){ 
      n = logs =~ c 
      println n[0][1] 
      println diff  
     }  
     } 
    } 
    } 
} 

任何想法？我一直在尋找其他的空指針問題，但它們看起來都是特定於代碼的，所以我想我只是將它添加到庫中。

Answer 1

NullPointerException on line scans.each 表示scans是空引用。 scans尚未初始化correclty。應該有這樣一行：def scan = []之前，所以scan被初始化爲一個空列表。如果你寫了def scan，掃描被初始化爲一個空指針。