java - How to delegate to default deserialization in custom deserializer in Jackson? -

suppose writing custom serialization class, process 1 of field default methods.

how that?

while serializing have jsongenerator#writeobjectfield().

but corresponding method deserialization?

regard code below:

import com.fasterxml.jackson.core.*; import com.fasterxml.jackson.databind.*; import com.fasterxml.jackson.databind.annotation.jsondeserialize; import com.fasterxml.jackson.databind.annotation.jsonserialize;  import java.io.ioexception; import java.util.objects;  public class trydelegate {     public static class myouterclassserializer extends jsonserializer<myouterclass> {        @override       public void serialize(myouterclass value, jsongenerator gen, serializerprovider serializers) throws ioexception, jsonprocessingexception {          gen.writestartobject();           gen.writeobjectfield("inner", value.getinner());           gen.writeendobject();       }    }     public static class myouterclassdeserializer extends jsondeserializer<myouterclass> {       @override       public myouterclass deserialize(jsonparser p, deserializationcontext ctxt) throws ioexception, jsonprocessingexception {            myouterclass ans = new myouterclass();           jsontoken token;           token = p.getcurrenttoken();          if( token != jsontoken.start_object ) {             throw new jsonparseexception("start object expected", p.getcurrentlocation());          }           if( !"inner".equals(p.nextfieldname() ) ) {             throw new jsonparseexception("'inner; field expected", p.getcurrentlocation());          }           myinnerclass inner = null;// how desrialize inner here default processing???          ans.setinner(inner);           token = p.nexttoken();          if( token != jsontoken.end_object ) {             throw new jsonparseexception("end object expected", p.getcurrentlocation());          }           return ans;        }    }     public static class myinnerclass {       private int value;        public int getvalue() {          return value;       }        public void setvalue(int value) {          this.value = value;       }        @override       public string tostring() {          return "{\"value\":" + value + "}";       }    }     @jsondeserialize(using = myouterclassdeserializer.class)    @jsonserialize(using = myouterclassserializer.class)    public static class myouterclass {        private myinnerclass inner;        public myinnerclass getinner() {          return inner;       }        public void setinner(myinnerclass inner) {          this.inner = inner;       }        @override       public string tostring() {          return "{\"inner\":" + objects.tostring(inner) + "}";       }    }     public static void main(string[] args) throws ioexception {        objectmapper mapper = new objectmapper();       string string;        myinnerclass inner = new myinnerclass();       inner.setvalue(12);        myouterclass outer = new myouterclass();       outer.setinner(inner);        string = mapper.writevalueasstring(outer);       system.out.println(string);        myouterclass outer2 = mapper.readvalue(string, myouterclass.class);       system.out.println(outer2); // inner not deserialized      } } 

how implement myouterdeserializer?

the deserializationcontext offers these tools.

after checking field name "inner", move next token, beginning of json object , use deserializationcontext deserialize json object myinnerclass object.

if (!"inner".equals(p.nextfieldname())) {     throw new jsonparseexception("'inner; field expected", p.getcurrentlocation()); } p.nexttoken(); // consumes field name token  myinnerclass inner = ctxt.readvalue(p, myinnerclass.class); 

the javadoc states

convenience method may used composite or container deserializers, reading one-off values contained (for sequences, more efficient fetch deserializer once whole collection).

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careful while using deserializationcontext. don't try recursively deserialize types have have registered custom deserializers.