EclipseJava。util。使用迭代器从HashMap获取ArrayList时出现NoTouchElementException

Question

我的代码是这样的：

HashMap<Integer, ArrayList<DebtCollectionReport>> mapOfAccounts = new HashMap<Integer, ArrayList<DebtCollectionReport>>();
  Set<String> agencyNames = agencyWiseAccountMap.keySet();
  Iterator iter = agencyNames.iterator();
  while (iter.hasNext()) {
    String agency = (String) iter.next();
    HashMap<Integer, ArrayList<DebtCollectionReport>> tempAccountsMap = agencyWiseAccountMap.get(agency);
    Set<Integer> accountSet = tempAccountsMap.keySet();
    Iterator itr = accountSet.iterator();
    while (itr.hasNext()) {
      mapOfAccounts.put((Integer) itr.next(), tempAccountsMap.get((Integer) itr.next()));
    }
  }

我得到异常跟踪：

>

 java.util.NoSuchElementException
    at java.util.HashMap$HashIterator.nextNode(Unknown Source)
    at java.util.HashMap$KeyIterator.next(Unknown Source)
    at com.cerillion.debtcollection.collector.CollectionExecutor.execute(CollectionExecutor.java:56)
    at com.cerillion.debtcollection.collector.CollectionExecutor.main(CollectionExecutor.java:24)
2017-11-14 05:00:43,733 ERROR  CollectionExecutor             [main      ] Exception occurred while executing Debt Collection java.util.NoSuchElementException
java.util.NoSuchElementException
    at java.util.HashMap$HashIterator.nextNode(Unknown Source)
    at java.util.HashMap$KeyIterator.next(Unknown Source)
    at com.cerillion.debtcollection.collector.CollectionExecutor.execute(CollectionExecutor.java:56)
    at com.cerillion.debtcollection.collector.CollectionExecutor.main(CollectionExecutor.java:24)

这发生在第行：

mapOfAccounts.put((Integer) itr.next(), tempAccountsMap.get((Integer) itr.next()));

可能的原因是什么？我如何解决

Answer 1

mapOfAccounts.put((Integer) itr.next(), tempAccountsMap.get((Integer) itr.next()));

问题应该是itr.next()，每次调用itr.next()，迭代器的索引都会向前移动一步。所以代码在这行移动了两步。。。 您应该使用var来接受该值，然后使用var：

int accountIdTemp = itr.next();
mapOfAccounts.put((Integer) accountIdTemp , tempAccountsMap.get((Integer) accountIdTemp ));

希望这有帮助

Answer 2

在下面的代码块中，您调用了hasNext()一次，但调用了next()两次^如果迭代有更多的值，{}将返回true，next()将返回迭代中的下一个元素

while (itr.hasNext()) {
  mapOfAccounts.put((Integer) itr.next(), tempAccountsMap.get((Integer) itr.next()));
}

您可以相应地更改此行：

while (itr.hasNext()) {
  Integer i1 = (Integer) itr.next();
  if(itr.hasNext()){
    mapOfAccounts.put(i1, tempAccountsMap.get((Integer) itr.next()));
  }
}