Removing an elements from basicdblist - mongodb-java

Question

Hi i have collection which contains around 200 documents looks like
e.g
"_id": 0,
"name": "Demarcus Audette",
"scores": [
{
"type": "exam",
"score": 30.61740640636871
},
{
"type": "quiz",
"score": 14.23233821353732
},
{
"type": "homework",
"score": 31.41421298576332
},
{
"type": "homework",
"score": 30.09304792394713
}
]
now i wrote code like
DBCursor cursor = collection.find().sort(new BasicDBObject("scores.score":1));
while( cursor.hasNext() )
{
DBobject obj=cursor.next();
BasicDBList list=(BasicDBList) Bobj.get("scores");
// Now here i am getting list of documents which consists of an scores array and i need to remove 3rd elements of it and save collection.... but how to do?
if i use for loop like
for(int i=0;i<list.size();i++)
{
list.remove(2);------ it gives an error here
collection.save(obj);
}
}

Answer 1

Are you sure that you can sort it as 'scores.score'. As 'scores' is a list of objects you cant reference objects inside list using dot notation. Error should be on that line.
Edit:
DBCursor cursor = collection.find();
while ( cursor.hasNext()) {
DBObject dbObject = cursor.next();
BasicDBList dbList = (BasicDBList) (dbObject.get("score"));
//then use java Collections.sort() to sort the List (refer to two methods at the bottom)
dbList.remove(3);
collection.save(dbObject);
}
Use one of the following to sort the DBList
1 . Using Lambda expression
Collections.sort(dbList, (o1, o2) -> Double.compare(((BasicDBObject) o1).getDouble("score"), ((BasicDBObject) o2).getDouble("score")));
or java 7 <
Collections.sort(dbList, new Comparator<Object>() {
public int compare(Object o, Object o2) {
if (((BasicDBObject) o).getDouble("score") >= ((BasicDBObject) o2).getDouble("score")) {
return 1;
}
return -1;
}
});

Answer 2

See this link https://gist.github.com/machadolucas/5188447/raw/e3f5c44c2be756c6087809df63f7ea8f4682ace9/Mongo3_1.java
I`m has been
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