问题描述
其他人则提到了正确的解决方案,而没有实际阐明。所以这里是:
Iterator<Map.Entry<String, Integer>> iterator =
group0.entrySet().iterator();
while (iterator.hasNext()) {
Map.Entry<String, Integer> entry = iterator.next();
// determine where to assign 'entry'
iEntryGroup = hasBeenAccusedByGroup(entry.getKey());
if (iEntryGroup == 1) {
assign(entry.getKey(), entry.getValue(), 2);
} else {
assign(entry.getKey(), entry.getValue(), 1);
}
// I don't kNow under which conditions you want to remove the entry
// but here's how you do it
iterator.remove();
}
另外,如果您想安全地在assign函数中更改映射,则需要传入迭代器(只能使用remove函数,并且只能使用一次)或条目来更改值。
解决方法
我正在尝试遍历HashMap
:
Map<String,Integer> group0 = new HashMap<String,Integer>();
…并提取中的每个元素group0
。这是我的方法:
// iterate through all Members in group 0 that have not been assigned yet
for (Map.Entry<String,Integer> entry : group0.entrySet()) {
// determine where to assign 'entry'
iEntryGroup = hasBeenAccusedByGroup(entry.getKey());
if (iEntryGroup == 1) {
assign(entry.getKey(),entry.getValue(),2);
} else {
assign(entry.getKey(),1);
}
}
这里的问题是对的每次调用assign()
都会从中删除元素group0
,从而修改其大小,从而导致以下错误:
Exception in thread "main" java.util.ConcurrentModificationException
at java.util.HashMap$HashIterator.nextEntry(HashMap.java:793)
at java.util.HashMap$EntryIterator.next(HashMap.java:834)
at java.util.HashMap$EntryIterator.next(HashMap.java:832)
at liarliar$Bipartite.bipartition(liarliar.java:463)
at liarliar$Bipartite.readFile(liarliar.java:216)
at liarliar.main(liarliar.java:483)
那么…当元素group0
动态变化时,我该如何遍历其中的元素呢?