JAVA java.util.ConcurrentModificationException:null 异常
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JAVA java.util.ConcurrentModificationException:null Exception
提问by Pratik
I am working on my code and getting "java.util.ConcurrentModificationException". I googled it and also know that such error comes only when you try to modify on-going iterative variable, which I don't feel in my case. Below is my code.
我正在处理我的代码并收到“java.util.ConcurrentModificationException”。我用谷歌搜索了一下，也知道只有当你尝试修改正在进行的迭代变量时才会出现这样的错误，在我的情况下我不觉得。下面是我的代码。
// This line is having an error
for(Statement s: _mConsumableStatements)
{
System.out.println("s:"+s);
Boolean isConflict=false;
Resource uri=s.getSubject();
System.out.println("uri:"+uri);
System.out.println("1");
if(RepStatementsAsHash.containsKey(uri))
{
System.out.println("2");
if(RepStatementsAsHash.get(uri).containsKey(RDFS.LABEL))
RepStatementsAsHash.get(uri).remove(RDFS.LABEL);
else if(RepStatementsAsHash.get(uri).containsKey(RDFS.SUBCLASSOF))
RepStatementsAsHash.get(uri).remove(RDFS.SUBCLASSOF);
else if(RepStatementsAsHash.get(uri).containsKey(RDFS.RANGE))
RepStatementsAsHash.get(uri).remove(RDFS.RANGE);
else if(RepStatementsAsHash.get(uri).containsKey(RDF.TYPE))
{
System.out.println("2.1");
Value RepTypeObject=RepStatementsAsHash.get(uri).get(RDF.TYPE);
Value ConsumableTypeObject=CStatements.get(uri).get(RDF.TYPE);
if (RepTypeObject.stringValue().equals(OWL.CLASS) || RepTypeObject.stringValue().equals(RDFS.CLASS))
{
if(ConsumableTypeObject.stringValue().equals(OWL.DATATYPEPROPERTY) || ConsumableTypeObject.stringValue().equals(OWL.OBJECTPROPERTY) || ConsumableTypeObject.stringValue().equals(RDF.PROPERTY))
{
isConflict=true;
//_mConflictingStatements.add(s);
}
else
{
RepStatementsAsHash.get(uri).remove(RepTypeObject);
}
}
else if(RepTypeObject.stringValue().equals(OWL.DATATYPEPROPERTY) || ConsumableTypeObject.stringValue().equals(OWL.OBJECTPROPERTY) || RepTypeObject.stringValue().equals(RDF.PROPERTY))
{
if (ConsumableTypeObject.stringValue().equals(OWL.CLASS) || ConsumableTypeObject.stringValue().equals(RDFS.CLASS))
{
isConflict=true;
//_mConflictingStatements.add(s);
}
else
{
}
}
else
{
if( !(RepTypeObject.stringValue().equals(OWL.DATATYPEPROPERTY) || ConsumableTypeObject.stringValue().equals(OWL.OBJECTPROPERTY) || RepTypeObject.stringValue().equals(RDF.PROPERTY) || ConsumableTypeObject.stringValue().equals(OWL.CLASS) || ConsumableTypeObject.stringValue().equals(RDFS.CLASS)) )
{
if(RepTypeObject.stringValue()!=ConsumableTypeObject.stringValue())
{
isConflict=true;
}
}
}
System.out.println("2.2");
if(!isConflict)
{
addStatementsInRepository(uri.stringValue(),c_import);
}
} // LABEL-TYPE
}
else // No URI Conflict
addStatementsInRepository(uri.stringValue(),c_import);
System.out.println("3");
}
It is showing error something like :
它显示的错误类似于：
11:13:24.405 ERROR - error while importing Sesame data:
java.util.ConcurrentModificationException: null
at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:859) ~[na:1.7.0_71]
at java.util.ArrayList$Itr.next(ArrayList.java:831) ~[na:1.7.0_71]
at org.apache.marmotta.platform.core.services.importer.rdf.RDFImporterImpl.importData2(RDFImporterImpl.java:433) [ulysses-core-1.0-alpha-2.jar:1.0-alpha-2]
How to resolve it?
如何解决？
回答by loafy
On this line, like many others in your code: RepStatementsAsHash.get(uri).remove(RepTypeObject);, you are iterating through the loop, and removing it whilst iterating. You can use an Iteratorto iterate through a list or map, and then remove elements using iterator.remove().
在这一行上，与您的代码中的许多其他人一样：RepStatementsAsHash.get(uri).remove(RepTypeObject);，您正在遍历循环，并在迭代时将其删除。您可以使用Iterator遍历列表或地图，然后使用iterator.remove().
