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Too many parameters error on the following $in query

I'm using jongo API - org.jongo.MongoCollection is the class.
I have list of object ids and converted the same as ObjectId[] and trying to query as follows
collection.find("{_id:{$in:#}}", ids).as(Employee.class);
The query throws the exception - "java.lang.IllegalArgumentException: Too
many parameters passed to query: {"_id":{"$in":#}}"
The query doesn't work as specified in the URL In Jongo, how to find multiple documents from Mongodb by a list of IDs
Any suggestion on how to resolve?
Thanks.

Try it with a List as shown on the docs:
List<String> ages = Lists.newArrayList(22, 63);
friends.find("{age: {$in:#}}", ages); //→ will produce {age: {$in:[22,63]}}
For example the following snippet I crafted quick & dirty right now worked for me (I use older verbose syntax as I am currently on such a system ...)
List<ObjectId> ids = new ArrayList<ObjectId>();
ids.add(new ObjectId("57bc7ec7b8283b457ae4ef01"));
ids.add(new ObjectId("57bc7ec7b8283b457ae4ef02"));
ids.add(new ObjectId("57bc7ec7b8283b457ae4ef03"));
int count = friends.find("{ _id: { $in: # } }", ids).as(Friend.class).count();

Java method for MongoDB collection.save()

I'm having a problem with MongoDB using Java when I try adding documents with customized _id field. And when I insert new document to that collection, I want to ignore the document if it's _id has already existed.
In Mongo shell, collection.save() can be used in this case but I cannot find the equivalent method to work with MongoDB java driver.
Just to add an example:
I have a collection of documents containing websites' information
with the URLs as _id field (which is unique)
I want to add some more documents. In those new documents, some might be existing in the current collection. So I want to keep adding all the new documents except for the duplicate ones.
This can be achieve by collection.save() in Mongo Shell but using MongoDB Java Driver, I can't find the equivalent method.
Hopefully someone can share the solution. Thanks in advance!

In the MongoDB Java driver, you could try using the BulkWriteOperation object with the initializeOrderedBulkOperation() method of the DBCollection object (the one that contains your collection). This is used as follows:
MongoClient mongo = new MongoClient("localhost", port_number);
DB db = mongo.getDB("db_name");
ArrayList<DBObject> objectList; // Fill this list with your objects to insert
BulkWriteOperation operation = col.initializeOrderedBulkOperation();
for (int i = 0; i < objectList.size(); i++) {
operation.insert(objectList.get(i));
}
BulkWriteResult result = operation.execute();
With this method, your documents will be inserted one at a time with error handling on each insert, so documents that have a duplicated id will throw an error as usual, but the operation will still continue with the rest of the documents. In the end, you can use the getInsertedCount() method of the BulkWriteResult object to know how many documents were really inserted.
This can prove to be a bit ineffective if lots of data is inserted this way, though. This is just sample code (that was found on journaldev.com and edited to fit your situation.). You may need to edit it so it fits your current configuration. It is also untested.

I guess save is doing something like this.
fun save(doc: Document, col: MongoCollection<Document>) {
if (doc.getObjectId("_id") != null) {
doc.put("_id", ObjectId()) // generate a new id
}
col.replaceOne(Document("_id", doc.getObjectId("_id")), doc)
}
Maybe they removed save so you decide how to generate the new id.

How to get array of document using Mongodb java?

How to get all the document under array in mongodb java. My Database is as below. Want to retrieve all the data under array 198_168_1_134.
below is some of What i tried,
eventlist.find(new BasicDBObject("$match","192_168_10_17"))
eventlist.find(new BasicDBObject("$elemMatch","192_168_10_17"))
eventlist.find(null, new BasicDBObject("$192_168_10_17", 1))

You have two options:
using .find() with cherry-picking which document you have to have fetched.
using the aggregation framework by projecting the documents.
By using .find() , you can do:
db.collection.find({}, { 192_168_10_17 : 1 })
By using the aggregation framework, you can do:
db.collection.aggregate( { $project : { 192_168_10_17 : 1 } } )
which will fetch only the 192_168_10_17 document data.
Of course, in order to get this working in Java, you have to translate these queries to a corresponding chain of BasicDBObject instances.

By using mongo java driver you can do this by following query -
eventlist.find(new BasicDBObject(), new BasicDBObject("198_168_1_134", 1))

Update an existing collection in MongoDB using Java-Hadoop connector

Is it possible to update existing MongoDB collection with new data. I am using hadoop job to read write data to Mongo. Required scenario is :-
Say first collection in Mongo is
{
"_id" : 1,
"value" : "aaa"
"value2" : null
}
after reading data from Mongo and processing data, MongoDB should contain
{
"_id" : 1,
"value" : "aaa"
"value2" : "bbb"
}
If possible, please provide some dummy code.

BasicBSONObject query=new BasicBSONObject();
query.append("fieldname", value);
BasicBSONObject update=new BasicBSONObject();
update.append("$set", new BasicBSONObject().append("newfield",value));
MongoUpdateWritable muw=new MongoUpdateWritable(query,update,false,true);
contex.write(key, muw);
query : is used for providing condition(matching condition).
update : is used for adding new field and value in existing collection.
MongoUpdateWritable:
3rd parameter is upsert value(same as mongodb)
4th parameter is multiple update in many documents in a collection.
Set in Driver class
job.setOutputValueClass(MongoUpdateWritable.class);

I have done it by extending org.apache.hadoop.mapreduce.RecordWriter and overriding write method of this class.

The Mongo-Hadoop Connector doesn't currently suppor this feature. You can open a feature request in the MongoDB Jira if you like.

I have done it by the stratio, if you are using spark, you can check it out!

Exists Query for multilple Document in Mongodb using java driver

If we want to check that the record is exists in Collection or not, then there is an operator $exists in Mongodb. But if we want to know multiple records exists in Collection then how can we check that in single query using java driver?
For Example I have two document:
{"key": "val1"}
{"key": "val2"}
Now if I want to check that 'val1' and 'val2' is exist or not then how can we do that in single query using java driver?
Note: here field name is same in both the documents.

You need to use $in operator for that
db.collection.find( { key : { $in : ['val1','val2'] } } );
equivalent java code might like this
List<string> values = new ArrayList<string>();
values.add("val1")
values.add("val2")
BasicDBObject query = new BasicDBObject();
query.put("key", new BasicDBObject("$in", values));
DBCursor cursor = yourcollection.find(query);
am not much of a java guy, this is going to be more or less same.