java - Best practice and implementation of a builder pattern when using JPA -

i have class suitable builder pattern, there many params , i'd rather not use ton of telescopic constructors.

my problem class jpa entity , new me.

having private final data members throwing error not initialised in constructor , far i'm aware, jpa requires empty protected constructor.

can please? example fantastic, i've included basic example of code below it's generic. i've emoted many of accessors , data members save space/time.

  @entity//(name= "table_name") //name of entity / table name public class bean implements serializable {      private static final long serialversionuid = 1l;      @id //primary key     @generatedvalue     long id;     private final datetime date;     private final string title;     private final string intro;       //used jpa     protected bean(){}      private bean(bean builder beanbuilder){         this.date = beanbuilder;         this.title = beanbuilder;          this.intro = beanbuilder;     }      public datetime getdate() {         return date;     }      public string gettitle() {         return title;     }      public static class beanbuilder builder{          private final datetime date;         private final string title;           //private optional           public beanbuilder(datetime date, string title) {             this.date = date;             this.title = title;         }          public beanbuilder intro(string intro){             this.intro = intro;             return this;         }          public beanbuilder solution(string solution){             this.intro = solution;             return this;         }          public bean buildbean(){             return new bean(this);         }      }  } 

member fields marked final must have value assigned during construction , value final (i.e. cannot change). consequence, all declared constructors must assign value all final fields.

this explain compiler error.

from jls:

a blank final instance variable must assigned @ end of every constructor of class in declared, or compile-time error occurs (§8.8, §16.9).