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What is the difference between map and flatMap and a good use case for each?
Can someone explain to me the difference between map and flatMap and what is a good use case for each?
16 Answers
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Fundamental difference between Hashing and Encryption algorithms
... hash function such as MD5 or SHA1/2/256/512. The point is that there's a one-way mapping going on. It's always a many:1 mapping (meaning there will always be collisions) since every function produces a smaller output than it's capable of inputting (If you feed every possible 1mb file into MD5, yo...
How can I remove duplicate rows?
...qlinthewild.co.za/index.php/2010/03/23/… Two SELECTs then were produced, one using the LEFT JOIN + WHERE IS NULL technique, the other using the NOT IN one. Then I proceeded with the execution plans, and guess what? The query costs were 18% for LEFT JOIN against 82% for NOT IN, a big surprise to me...
Copy files from one directory into an existing directory
...lly like this syntax, but for some reason it doesn't work with mv. Does anyone know why?
– Martin von Wittich
Sep 16 '13 at 11:18
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How to update a value, given a key in a hashmap?
...ng function, which will be called to compute a new value based on existing one.
For example,
Map<String, Integer> words = new HashMap<>();
words.put("hello", 3);
words.put("world", 4);
words.computeIfPresent("hello", (k, v) -> v + 1);
System.out.println(words.get("hello"));
Altern...
Should I use SVN or Git? [closed]
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SVN is one repo and lots of clients. Git is a repo with lots of client repos, each with a user. It's decentralised to a point where people can track their own edits locally without having to push things to an external server.
SVN i...
Try-catch speeding up my code?
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One of the Roslyn engineers who specializes in understanding optimization of stack usage took a look at this and reports to me that there seems to be a problem in the interaction between the way the C# compiler generates loca...
Injecting $scope into an angular service function()
...s, other services etc).
I am sure, various approaches would work for you. One is this:
Since the StudentService is in charge of dealing with student data, you can have the StudentService keep an array of students and let it "share" it with whoever might be interested (e.g. your $scope). This makes ...
Good Java graph algorithm library? [closed]
Has anyone had good experiences with any Java libraries for Graph algorithms. I've tried JGraph and found it ok, and there are a lot of different ones in google. Are there any that people are actually using successfully in production code or would recommend?
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Drop multiple tables in one shot in mysql
How to drop multiple tables from one single database at one command.
something like,
4 Answers
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