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MongoDB (Java): efficient update of multiple documents to different(!) values

I have a MongoDB database and the program I'm writing is meant to change the values of a single field for all documents in a collection. Now if I want them all to change to a single value, like the string value "mask", then I know that updateMany does the trick and it's quite efficient.
However, what I want is an efficient solution for updating to different new values, in fact I want to pick the new value for the field in question for each document from a list, e.g. an ArrayList. But then something like this
collection.updateMany(new BasicDBObject(),
new BasicDBObject("$set",new BasicDBObject(fieldName,
listOfMasks.get(random.nextInt(size)))));
wouldn't work since updateMany doesn't recompute the value that the field should be set to, it just computes what the argument
listOfMasks.get(random.nextInt(size))
would be once and then it uses that for all the documents. So I don't think there's a solution to this problem that can actually employ updateMany since it's simply not versatile enough.
But I was wondering if anyone has any ideas for at least making it faster than simply iterating through all the documents and each time do updateOne where it updates to a new value from the ArrayList (in a random order but that's just a detail), like below?
// Loop until the MongoCursor is empty (until the search is complete)
try {
while (cursor.hasNext()) {
// Pick a random mask
String mask = listOfMasks.get(random.nextInt(size));
// Update this document
collection.updateOne(cursor.next(), Updates.set("test_field", mask));
}
} finally {
cursor.close();
}```

MongoDB provides the bulk write API to batch updates. This would be appropriate for your example of setting the value of a field to a random value (determined on the client) for each document.
Alternatively if there is a pattern to the changes needed you could potentially use find and modify operation with the available update operators.

RecyclerView Adapter Map instead of Arraylist [duplicate]

Edit: Figured it out, check my posted answer if you're having similar issues.
I know there are several questions about this issue, but none of their solutions are working for me.
In my model class I have made sure to use List instead of Arraylist to avoid Firebase issues, but am still getting this error. It's a lot of code but most questions ask for all the code so I'll post it all.
TemplateModelClass.java
//
I've used this basic model successfully many times. For the
HashMaps<String, List<String>>,
the String is an incremented Integer converted to String. The List's are just Strings in a List. Here's some sample JSON from Firebase:
//
Formatted that as best as I could. If you need a picture of it let me know and I'll get a screenshot
And am getting this error, as stated in the title:
com.google.firebase.database.DatabaseException: Expected a Map while deserializing, but got a class java.util.ArrayList
The most upvoted question about this seems to have something to do with a problem using an integer as a key, but I think I've avoided that by always using an integer converted to a string. It may be interpreting it strangely, so I'll try some more stuff in the meantime. Thanks for reading!

Alright, figured it out. If anyone reading this has this problem and are using incremented ints/longs/whatever that get converted to strings, you must add some characters to the converted int. Firebase apparently converts these keys back into non-Strings if it can be converted.
For example, if you do something like this:
int inc = 0;
inc++; // 1
map.put(String.valueOf(inc), someList);
Firebase interprets that key as 1 instead of "1".
So, to force Fb to intepret as a string, do something like this:
int inc = 0;
inc++; // 1
map.put(String.valueOf(inc) + "_key", someList);
And everything works out perfectly. Obviously if you also need to read those Strings back to ints, just split the string with "[_]" and you're good to go.

The main issue is that you are using a List instead of a Map. As your error said, while deserializing it is expectig a Map but is found an ArrayList.
So in order to solve this problem youd need to change all the lists in your model with maps like this:
private Map<String, Object> mMapOne;
After changing all those fileds like this, you need also to change your public setters and getters.
Hope it helps.

Assign text to JLabels from ArrayList

I'm not actually sure how to ask this question because its very confusing. I have a java app that has a MVC structure, which gets data from a database. I retrieve String ArrayList of data from a JDBC query. It contains information about Competitors in a race (eg: Name, Race_no, Start_Time, Swim_Time, Bike_Time, Finish_Time etc). The list size will vary week to week depending on the number of the competitors who raced that week. I have no problem getting the data from the database, but when I pass the information to the controller to pass to the view, I am having trouble assigning the data to a JLabel. So far the data is sent as one large array so I need to somehow split the array up in blocks of 12 (which is how many JLabels are required to be set for each competitor). I then set each of those 12 JLabels into its own JPanel ArrayList - then dynmically add to one JPanel for printing. My question is, how do I split the ArrayList to get the first 12, then the second lot of 12, etc.. I have tried doing a nested loop and set the size to 12, but of course that only gets the first 12 everytime. Maybe I need to store the data from the JDBC result set as something else.. I really need some guidance on this as have been stuck for days.
nb: I had this working as one large method in the data handler class, where I would use the while(rs.next()) to do all the work, but because of the MVC structure, I need to break the code up: This is the desired outcome:
EDIT:
I have implement this code which give me the desired output, but now having trouble assigning the JLabel variables with the data in the [j] loop:
<pre>
public void getRaceLabels()
{
ArrayList<String[]> raceLabels = dh.getRaceTimeLabels();
//System.out.println(raceLabels);
for (int i = 0; i < raceLabels.size(); i++)
{
String[] element = (String[]) raceLabels.get(i);
//System.out.println(element);
for (int j = 0; j < element.length; j++)
{
System.out.print(element[j]+" ,");
}
System.out.println("break");
}
</pre>

Create yourself a POJO which represents the basic information you need for a single record.
When loading the data from the database, load this data into the POJO.
Now, for each panel, you just need to pass it a single object, meaning you can now get away with using a simple iterator instead

XPages - Lotus Domino Java - getDocumentByKey

In a Java class in my XPages application, I'm trying to get a handle on a Notes Document in a Notes View. The Notes View contains several Notes Documents. To get the Notes Document I want, I use 2 keys. This produces an error. If I use just one key, the first Notes Document in the Notes View is returned. The Notes View contains two sorted columns. The first column contains the empLang value, the second column contains the templateType value. Here is my code:
String empLang = "en";
String templateType = "C";
Database dbCurr = session.getCurrentDatabase();
String viewName = "vieAdminTemplates" + empLang;
View tview = dbCurr.getView(viewName);
Vector viewKey = new Vector();
viewKey.addElement(empLang);
viewKey.addElement(templateType); // this line causes the code to fail
Document templateDoc = tview.getDocumentByKey(viewKey);
What could be the cause of this problem?

A couple of ideas
1) You could concatenate the key into a single column since you said that worked. Something like 'en~C'
2) You could use the database.search method where you include a string of formula language that isolates the document you want. It returns a collection, and then you pull the document from there.

getDocumentByKey works with multiple columns. There's a known problem with doubles, but you're not hitting that there. One thing that stands out is the second column is just a single letter. That could be considered as a Char instead of a String, either when you do addElement or by the view.
I'd recommend debugging out what data type they are. viewKey.get(1).getClass().getName() I think gives you the class it's stored as. Doing the same for the View Column value.
When you say it causes the code to fail, how does it fail? Does it just not return anything or throw an error?
My next step would be to try testing it where the View and the Vector contain more than one character, e.g. "CC", to help check if there's an underlying issue with Java getDocumentByKey and single characters.

I'm very sorry. The problem here is that the view name in the code is incorrect. There is a view "vieAdminTemplates" but it does not have a second column containing the value "C". With the correct view, the code works fine. Thanks for taking the time to respond to my question.

How do you handle incomplete data in a Processing table?

I'm parsing a CSV using Processing's Table interface, but some rows are missing some data. I want to pull all the data available into my table, but I'm not sure how to handle the missing data--I keep getting NullPointerException when I loop over the table with dataTable.getInt on the missing values.
I don't have a background in statically typed languages, so I've no idea how to conditionally assign this data short of putting a separate try/catch around each assignment. Surely there's a better way?

Before calling dataTable.getInt method check if dataTable is not null like
if(dataTable != null) {
int my_nt = dataTable.getInt
}
//else skip since it is empty

Since your're using getInt--you should perform a regex search/replace ,<not numeric>, with ,<some int>,. In your case it may be as simple as replacing ,, with ,0,
Also, as Hassan suggests, double check that dataTable is not null.

Ok, so I figured out a way to do this:
First, call dataTable.makeNullEmpty(), which turns all the null values into empty strings.
Then, you can use a pattern like this:
String total_value = dataTable.getString(i, 4);
if(total_value.length() > 0) s.total_value = parseInt(total_value);
and you get assignment only if an int is there to be parsed.