CODEWITHSUNDEEP
java
Kris
Kris

Reputation: 10297

Pragmatic Way to Override Equals for Classes With Many Fields

I have a class that contains a large number of data members - some of which are user defined classes of their own, Lists, HashMaps, etc...

Let's say there are 20 data members.

Is there a more pragmatic way to override the equals() operator other than checking for equality against every single field?

For example (using Guava):

HashMap<k,v> dataMember1;
String dataMember2;
CustomClass dataMember3;
etc...

@Override   
public boolean equals(Object obj) {
    Objects.deepEquals(this.dataMember1, obj.dataMember1) &&
    Objects.equals(this.dataMember2, obj.dataMember2) &&
    Objects.equals(this.dataMember3, obj.dataMember3) &&
    etc...
}

I've seen these large blocks in production code before, but they always seemed so redundant.

Upvotes: 1

Views: 96

Answers (2)

jihor
jihor

Reputation: 2599

There is an annotation processor for Java called Lombok, which offers some nice annotations to deal with boilerplate code, including @EqualsAndHashCode.

In cases when immutability is acceptable/desirable, Immutables and Google AutoValue libraries provide annotations for creating value classes along with all the boilerplate code, including equals() method.

Upvotes: 2

Igor
Igor

Reputation: 33992

I think how you're implementing the equals is fine, however it may be a code smell that you should pull some of those fields into their own classes. Then you would be comparing fewer fields, as each class can implement its own equals.

Regardless, the problem is a symptom, not a cause.

Upvotes: 1

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