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Multiple threads modifying a collection in Java?

The project I'm working on requires a whole bunch of database queries. Basically, there are two types of queries that I use:

  • read from the excel file, check several parameters and execute the request to get into the database. These hits are then recorded as a series of custom classes. Any hit can (and most likely will) happen more than once, so this part of the code checks and updates the entry in the implementation of the user list, which extends the ArrayList.

  • for each hit found, do a detailed query and analyze the output so that the classes created in (I) get detailed information.

I decided that I would use several threads for time optimization. However, I cannot find a good way to solve the problem associated with the collection in which these items are stored. it is assumed that all execution objects must be modified both (I) and (II).

I intentionally did not make c / p code, as these would be big pieces of code to make any sense. Hope this makes sense with the description above.

Thank,

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2 answers

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