I have the following data stored as lists: I need to group it as follows What I have tried is the following: But this doesn’t give the desired result. Answer Here’s how you can apply nested groupingBy To collect it in the order encountered, you can use a LinkedHashMap, Result:
Tag: treemap
Converting List to TreeMap java lambda
I’m trying to convert a List<String> to a TreeMap<Long, CustomClass> The key is the same as the list items but just parsed to Long, the value is just a call to new CustomClass(). How can I achieve this using lambda functions? the above code errors out, with the following error, Answer For example:
How to match equals() and hashCode in streams?
I have a stream where I am aggregating some data like this: The problem is that by adding this comparator I am braking the contract between hashCode() and equals() and at the end I have duplicate keys: Has anyone some ideas how can I fix this? Or is there a way to sort the final object ( Map<String, Map<String, Map<EventType,
putting value in Treemap understanding issues
I was running through a leetcode problem. and found a solution in the discussion section problem- https://leetcode.com/problems/stock-price-fluctuation/ solution- but I do not understand the following parts. if someone could explain that would be great Answer To solve the problem you need to know how often the stock is traded for a particular price. An example: it was traded at timestamp
How to iterate from a given key in Java TreeMap
I have a TreeMap, and want to get a set of K smallest keys (entries) larger than a given value. I know we can use higherKey(givenValue) get the one key, but then how should I iterate from there? One possible way is to get a tailMap from the smallest key larger than the given value, but that’s an overkill if
Comparing the contents of two Treemaps
I have two TreeMaps that I want to compare. I currently have it written down like below but I feel like this could be written more efficiently. I tried looking in to comparators, but I don’t think that’s something I can use for my use-case. The maps are Treemaps because the key must be case-insensitive. Thanks in advance Answer If
How to sort the keySet() of a TreeMap with keys containing number?
I’ll briefly describe what I did and then show how the result I got, differs from my desired result. Thanks in advance for any suggestions. Java code was created in a java online compiler and is executable there without error message in any case. Java online compiler, which was used Short description: I want to assign a boolean value to
How treemap handles case of putting key on same index?
I tried out following code: public static void main (String[] args) throws java.lang.Exception { // sorting based on number of dots Map map =new TreeMap((o1, o2) -&…
Why do I get an error when entering child classes to a TreeMap defined for their parent? [closed]
Closed. This question is not reproducible or was caused by typos. It is not currently accepting answers. This question was caused by a typo or a problem that can no longer be reproduced. While similar questions may be on-topic here, this one was resolved in a way less likely to help future readers. Closed 2 years ago. Improve this question
How to write custom comparator in java?
I want to store key-value pairs in TreeMap and sort the entries based on the value of key as per the following logic: “type” (case insensitive) key should be at first. the key start with “metadata” (case insensitive) should be at last in ascending order rest of the keys(case insensitive) should be in middle in ascending order I am using