How do I read a data from a JSON file with high efficiency in Java with Jackson?

Question

I store all static data in the JSON file. This JSON file has up to 1000 rows. How to get the desired data without storing all rows as

Answer 1

You can use DSM stream parsing library for memory, CPU efficiency and fast development. DSM uses YAML based mapping file and reads the whole data only once.

Here is the solution of your question:

Mapping File:

params:
   colorsToFilter: ['Blue','Red']  # parameteres can be passed programmatically
result:
   type: array
   path: /.*colors  # path is regex
   filter: params.colorsToFilter.contains(self.data.color)  # select only color that exist in colorsToFilter list
   fields:
      color: 
      code:
         type: array

Usage of DSM to parse json:

DSM dsm = new DSMBuilder(new File("path/maping.yaml")).create(Colors.class);
List object = (List) dsm.toObject(jsonData);

System.out.println(object);

Output:

[Colors{color='Blue', code=[012, 0324, 15478, 7412]}, Colors{color='Red', code=[145, 001, 1, 7879, 123984, 89]}]