EntityEquals.java

package fi.insomnia.bortal.model;

import java.util.Date;
import java.util.Random;

import javax.persistence.MappedSuperclass;
import javax.persistence.Transient;

import org.eclipse.persistence.annotations.OptimisticLocking;
import org.eclipse.persistence.annotations.OptimisticLockingType;

@MappedSuperclass
@OptimisticLocking(type = OptimisticLockingType.CHANGED_COLUMNS)
public abstract class EntityEquals {

    @Override
    public final String toString() {
        return new StringBuilder(this.getClass().getCanonicalName()).append("[").append(getId()).append("]").toString();
    }

    @Transient
    private Integer rndid;

    protected abstract Object getId();

    @Override
    public boolean equals(Object o) {
        boolean ret = false;
        if (this == o) {
            ret = true;
        } else if (o != null && o instanceof EntityEquals && this.getClass().getCanonicalName().equals(o.getClass().getCanonicalName())) {
            EntityEquals oobj = (EntityEquals) o;
            if (getId() == null) {
                ret = (getRndid().equals(oobj.rndid));
            } else {
                ret = getId().equals(oobj.getId());
            }
        }
        return ret;
    }

    private Integer getRndid() {
        if (rndid == null) {
            Random rng = new Random(new Date().getTime());
            rndid = Integer.valueOf(rng.nextInt());
        }
        return rndid;
    }

    @Override
    public final int hashCode() {
        return ((rndid != null || getId() == null) ? getRndid() : getId().hashCode());
    }
}