CODEWITHSUNDEEP
javahibernatemany-to-manyequalshashcode
WoutVanAertTheBest
WoutVanAertTheBest

Reputation: 820

hashCode() and equals() methods of a composite id class

It's been days I'm trying to find the correct way to implement the equals() and hashCode() methods of a composite-id class.

The trouble I'm facing when I try to update the main object (Gara) are:

  1. StackOverflow
  2. DuplicateKeyException: a different object with the same identifier value was already associated with the session
  3. org.hibernate.ObjectNotFoundException: No row with the given identifier exists

My Composite-id class

@Embeddable 
public class GaraAgenziaId implements Serializable {

    private static final long serialVersionUID = 4934033367128755763L;

    static Logger logger = LoggerFactory.getLogger(GaraAgenziaId.class);

    private Gara gara;

    private Agenzia agenzia;

    @ManyToOne
    public Gara getGara() {
        return gara;
    }

    public void setGara(Gara gara) {
        this.gara = gara;
    }

    @ManyToOne
    public Agenzia getAgenzia() {
        return agenzia;
    }

    public void setAgenzia(Agenzia agenzia) {
        this.agenzia = agenzia;
    }


    @Override
    public String toString() {
        return "GaraAgenziaId [Gara=" + gara + ", agenzia=" + agenzia
                + "]";
    }


}

Upvotes: 5

Views: 7435

Answers (1)

WoutVanAertTheBest
WoutVanAertTheBest

Reputation: 820

these seems to work very well:

 public boolean equals(Object o) {
        if (this== o) return true;
        if (o ==null|| getClass() != o.getClass()) return false;

        GaraAgenziaId that = (GaraAgenziaId) o;

        if (gara !=null?!gara.equals(that.gara) : that.gara !=null) return false;
        if (agenzia !=null?!agenzia.equals(that.agenzia) : that.agenzia !=null)
            return false;

        return true;
    }

    public int hashCode() {
        int result;
        result = (agenzia !=null? agenzia.hashCode() : 0);
        result =31* result + (gara !=null? gara.hashCode() : 0);
        return result;
    }

Upvotes: 5

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