How Jackson implements a conversion between a JSON string and a generic list collection

Objective:

Jackson Common methods:

Jackson is the usual two ways to handle the conversion between generic Java objects and JSON are the writevalueasstring () and ReadValue () methods of the Objectmapper class that can be implemented.

However, if it is to be turned into a list collection of the specified generics, such as list<user>. You need to deserialize the complex type to generics first

Collection Type;

To illustrate:

If it is a list<user> collection, then use Objectmapper's gettypefactory (). Constructparametrictype (List.class, User.class);

If it is a hashmap<string,user> collection, then use Objectmapper's gettypefactory (). Constructparametrictype (HashMap.class, String.class,user. Class);

code implementation:

Public final objectmapper mapper = new objectmapper ();           public static void main (String[] args)  throws  exception{          javatype javatype =  getcollectiontype (Arraylist.class, yourbean.class);          List<YourBean> lst =   (list<yourbean>) Mapper.readvalue (jsonstring,  Javatype);     }          /**            *  get collection type    of generics        *  @param  collectionClass  Generics collection            *  @param  elementClasses  Element Classes             *  @return  javatype java Type             *  @since  1.0            */       public static javatype getcollectiontype ( class<?> collectionclass, class<?>... elementclasses)  {            return mapper.gettypefactory (). ConstructParametricType ( collectionclass, elementclasses);        }

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How Jackson implements a conversion between a JSON string and a generic list collection