Question

I have an issue where I am trying to use test the equals method of a superclass using objects of a subclass:

My superclass is:

public class Excluded_DateTime implements Serializable {

private Date fromDate;   
private Time fromTime;
private Date toDate;   
private Time toTime;
private Valid active;

And the subclass differs by having an identifier as a key:

public class Classifier_Excluded_DateTime implements Serializable {

private Integer classifierExcludedDateTimeNo;    
private Excluded_DateTime classifierExcludedDateTime;   

So I want to test the equality of Classifier_Excluded_DateTime objects without using the field classifierExcludedDateTimeNo.

But what I am finding is that the equals method of the superclass is never called.

The NetBeans generated equals and hashCode methods of the superclass are as follows:

@Override
    public int hashCode() {        
        int hash = 7;
        hash = 23 * hash + (this.fromDate != null ? this.fromDate.hashCode() : 0);
        hash = 23 * hash + (this.fromTime != null ? this.fromTime.hashCode() : 0);
        hash = 23 * hash + (this.toDate != null ? this.toDate.hashCode() : 0);
        hash = 23 * hash + (this.toTime != null ? this.toTime.hashCode() : 0);
        hash = 23 * hash + (this.active != null ? this.active.hashCode() : 0);
        return hash;
    }

@Override
public boolean equals(Object obj) {        
    if (obj == null) {
        return false;
    }
    if (getClass() != obj.getClass()) {
        return false;
    }
    final Excluded_DateTime other = (Excluded_DateTime) obj;
    if (this.fromDate != other.fromDate && (this.fromDate == null || !this.fromDate.equals(other.fromDate))) {
        return false;
    }
    if (this.fromTime != other.fromTime && (this.fromTime == null || !this.fromTime.equals(other.fromTime))) {
        return false;
    }
    if (this.toDate != other.toDate && (this.toDate == null || !this.toDate.equals(other.toDate))) {
        return false;
    }
    if (this.toTime != other.toTime && (this.toTime == null || !this.toTime.equals(other.toTime))) {
        return false;
    }
    if (this.active != other.active) {
        return false;
    }
    return true;
}

And those of the subclass as follows:

@Override
public int hashCode() {                
    int hash = 7;
    hash = 79 * hash + (this.getClassifierExcludedDateTimeNo() != null ? this.getClassifierExcludedDateTimeNo().hashCode() : 0);
    return hash;
}

@Override
public boolean equals(Object obj) {        
    if (obj == null) {
        return false;
    }
    if (getClass() != obj.getClass()) {
        return false;
    }
    if (! super.equals(obj)) {            
        return false;
    }
    final Classifier_Excluded_DateTime other = (Classifier_Excluded_DateTime) obj;   

    if (this.getClassifierExcludedDateTimeNo() != other.getClassifierExcludedDateTimeNo() && (this.getClassifierExcludedDateTimeNo() == null || !this.classifierExcludedDateTimeNo.equals(other.ClassifierExcludedDateTimeNo))) {            
        return false;
    } 
    return true;
}

Can I do what I’m trying to do by amending these methods of either class?

I am trying to test whether two instance of Classifier_Excluded_DateTime are the same without including the field classifierExcludedDateTimeNo in the comparison.

Answer 1

You are not declaring Classifier_Excluded_DateTime as a subclass of Excluded_DateTime. To do that, you would need to say:

public class Classifier_Excluded_DateTime extends Excluded_DateTime {

Right now, it seems more like you are treating Excluded_DateTime as a kind of delegate of Classifier_Excluded_DateTime, as you have a member instance variable inside of Classifier_Excluded_DateTime that is of type Excluded_DateTime (the place where you say private Excluded_DateTime classifierExcludedDateTime;). I don’t think that’s your intent, since you are talking about subclasses and superclasses in your post.

(Update: removed error where I thought there was not an explicit super.equals() call).