java - Overwritten hashCode,equals and get/set- methods necessary in a JPA Entity? -

i have question jpa. absolutly necessary create overwritten hashcode method , overwritten equals method this:

@override public int hashcode() {     final int prime = 31;     int result = 1;     result = prime * result + ((id == null) ? 0 : id.hashcode());     return result; }  @override public boolean equals(object obj) {     if (this == obj) {         return true;     }     if (obj == null) {         return false;     }     if (getclass() != obj.getclass()) {         return false;     }     usercontent other = (usercontent) obj;     if (id == null) {         return false;     } else if (!id.equals(other.id)) {         return false;     }     return true; } 

also know, if get- , set methods must implemented. or can leave out , in scenarios can leave out?

are method necessary too?

@override public boolean isnew() {     return this.id == null; } 

i use eclipselink jpa provider.

thanks lot! maik

overriding hashcode() , equals() important entities part of collections. not strictly required other entities, practice override them systematically, don't forget add them later when add new relationships.

setters , getters not mandatory. again, practice make instance fields private , access them through public getters , setters.

as isnew() method, common utility method , not @ required.