Check if value exists in mongodb - mongodb-java

Question

I'm trying to write a method that will check if a user_id is in the DB and then operate on the user_id.The portion of code that I'm stuck on is this:
DBObject query = new BasicDBObject(user_id,new BasicDBObject("$regex", true));
DBCursor result = dBcollection.find(query);
if (result.equals("true")) {
System.out.println("found");
//do stuff
}
else{
//do other stuff
}
My database is set up this way:
{ "_id" : { "$oid" : "53b4443ad121894f16ea3699"} , "user_id" : "1683777896" , "countries" : { "JA" : 1}}
{ "_id" : { "$oid" : "53b4443ad121894f16ea369a"} , "user_id" : "453121657" , "countries" : { "TU" : 1}}
I want to be able to query on the user_id and then operate on the record associated with that user_id but I can't figure out the correct syntax in java for the "if" statement.

Answer 1

Use this to query for the document with that user id:
DBObject query = new BasicDBObject("user_id", user_id);
Use this for the if statement to determine if the find actually found that user id:
if (result.hasNext())
If that doesn't go into the if statement, show us the code that gets the database and dBcollection, and make sure you are connecting to the right database and collection name.