Compare object fields of different classes in Java

Question

I have two objects, each of which have tens of fields:

Class1 {
    int firstProperty;
    String secondProperty;
    ...
}

Class2 {
    int propertyOne;
    St         


        

Answer 1

Having two classes with fields that have similar meanings, I'd consider declaring an interface.

Class1 implements MyInterface {
    int firstProperty;
    String secondProperty;
    ...
    int getOne() {
        return firstProperty;
    }
    String getTwo() {
        return secondProperty;
    }

}

Class2 implements MyInterface {
    int propertyOne;
    String propertyTwo;
    ...
    int getOne() {
        return propertyOne;
    }
    String getTwo() {
        return propertyTwo;

    ...


}

And an interface with default implementation of isEqualTo:

MyInterface {
    int getOne();
    String getTwo();
    ...

    boolean isEqualTo(MyInterface that) {
        return that != null &&
            this.getOne() == that.getOne() &&
            this.getTwo().equals(that.getTwo()) && //add null checks!

            ...;
    }
}

There is a risk of isEqualTo being overridden - make sure it never happens.